Jollystolly - Alvis Stalwart

Page 1 of 155 Rev B © Hugh Neve 2006

JollyStolly

Builder’s manual…

Prototype: #0001

(Aged 1 yr+)



DISCLAIMER: THE VEHICLE REPRESENTED IN THESE PLANS IS PROVIDED "AS-IS"

WITHOUT WARRANTY OR GUARANTEE, EITHER EXPRESSED OR IMPLIED, INCLUDING OF FITNESS FOR ANY PARTICULAR PURPOSE.

ANY USE YOU MAKE OF THESE DESIGNS IS ENTIRELY AT YOUR OWN SOLE RISK. THE AUTHOR DOES NOT HAVE ANY CONTROL

WHATSOEVER OVER THE FINAL MANUFACTURED QUALITY OR

PHYSICAL INTEGRITY OF ANY VEHICLE OR DEVICE IN WHOLE OR IN PART BASED ON THESE DESIGNS AND TO THE MAXIMUM EXTENT PERMITTED IN APPLICABLE LAW, THE AUTHOR IS NOT LIABLE IN ANY WAY FOR ANY LOSS, DAMAGE OR INJURY YOU OR ANY THIRD PARTY

MAY INCUR AS A RESULT, DIRECTLY OR INDIRECTLY, OF YOUR USE OF THESE DESIGNS. THE AUTHOR AND THE VEHICLE REPRESENTED IN THESE PLANS (‘THE

VEHICLE’) HAS NO LINKS TO ALVIS VEHICLES (BAE LAND SYSTEMS) AND NO ENDORSEMENT BY ALVIS VEHICLES (BAE LAND SYSTEMS) IS INFERRED BY ITS EXISTENCE. THE VEHICLE IS INTENDED AS A HOMAGE TO THE DESIGNERS, ENGINEERS AND USERS OF THE

STALWART.

THIS DOCUMENT IS AN OUTLINE GUIDE TO THE CONSTRUCTION OF A ONE-OFF TOY FOR PERSONAL USE: THIS DOCUMENT SHALL NOT BE USED AS THE BASIS FOR ANY COMMERCIAL ACTIVITIES. ITS

EXISTENCE IN NO WAY PREJUDICES THE RIGHTS OF ALVIS VEHICLES (BAE LAND SYSTEMS) TO EXPLOIT OR LICENSE THE CONCEPT OF SCALE VERSIONS OF THEIR DESIGNS.

This means:

• This is only a guide, not a detailed ‘how-to’; • Don’t blame me if you hurt yourself or anyone else if you try to

use this guide to make one like mine; • Don’t rip off Alvis (BAE LAND SYSTEMS); • Don’t rip me off;

JollyStolly


Table of Contents.

1 Introduction...................................................................... 12 2 Description ....................................................................... 13 3 Common Sense ................................................................. 14 3.1 General Techniques ........................................................ 15 3.1.1 Measuring. ............................................................... 15 3.1.2 Sawing. ................................................................... 16 3.1.3 Drilling .................................................................... 16 3.1.4 Planing .................................................................... 17 3.1.5 Sanding ................................................................... 17 3.1.6 Grinding .................................................................. 18 3.1.7 Welding ................................................................... 18 3.1.8 Joints in Wood.......................................................... 19 3.1.9 Batteries.................................................................. 22 3.1.10 Chains and Sprockets. ............................................ 22 3.1.11 Spray-painting....................................................... 23

3.2 Operation. ..................................................................... 24 4 Materials / Other .............................................................. 25 5 Building Sequence............................................................. 26 5.1 Hull .............................................................................. 26 5.1.1 Components............................................................. 26 5.1.2 Procedure. ............................................................... 26

5.2 Load-bed....................................................................... 32 5.2.1 Components............................................................. 32 5.2.2 Procedure. ............................................................... 32

5.3 Cab .............................................................................. 34 5.3.1 Components............................................................. 34 5.3.2 Procedure. ............................................................... 35

5.4 Metalwork. .................................................................... 40 5.4.1 Stub Axles ............................................................... 40 5.4.2 Axle-beams.............................................................. 41 5.4.3 Rear axle-beams....................................................... 42 5.4.4 Driveshafts. ............................................................. 43 5.4.5 Finishing. ................................................................. 44

5.5 Steering Gear. ............................................................... 45 5.5.1 Description............................................................... 45 5.5.2 Process.................................................................... 46

5.6 Drive and Transmission ................................................... 48 5.6.1 Description............................................................... 48 5.6.2 Design Considerations. .............................................. 48 5.6.3 Procedure. ............................................................... 53

5.7 Assembly....................................................................... 56 5.8 Electrical. ...................................................................... 57

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5.9 Testing.......................................................................... 60 5.9.1 Safety: .................................................................... 60 5.9.2 Tyre pressures.......................................................... 60

5.9.3 Steering function ...................................................... 60 5.9.4 Drive functions ......................................................... 61 5.9.5 Combined Functions .................................................. 61 5.9.6 Other electrical ......................................................... 61

5.10 Finishing & Painting. .................................................... 62

List of Tables.

Table 1: Acronyms & Abbreviations................................................ 8 Table 2: Conversion Factors.......................................................... 9 Table 3: Revision History. ........................................................... 11

List of Appendices. APPENDIX A: Materials List ......................................................... 64 APPENDIX B: Steering Strategies................................................. 68 APPENDIX C: Drive Control Strategies.......................................... 78 APPENDIX D: Forces Involved. .................................................... 82 APPENDIX E: Weight, Balance & Performance. .............................. 87 APPENDIX F: Wiper-motor mounting. ........................................... 94 APPENDIX G: Parental Override................................................... 98 APPENDIX H: Things I didn't get round to ....................................101 APPENDIX I: Crane……….…………………………………………………………………..103

APPENDIX J: Kitchen Pass..........................................................113

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List of Figures.

Figure 1: Alignment of hull-side and bulkheads. ............................ 27 Figure 2: Trimming of hull-sides. ................................................. 28 Figure 3: Faces of base that are required to be trimmed................. 29 Figure 4: Part-Assembled Hull ..................................................... 30 Figure 5: Cab Assembly.............................................................. 34 Figure 6: Cab base and cab rear-panel. ........................................ 35 Figure 7: Cab base, rear-panel and front-panel. ............................ 36 Figure 8: Cab after fitment of right-hand side-panel....................... 36 Figure 9: Cab with front, rear and both side-panels in place............ 37 Figure 10: Seat added to cab. ..................................................... 37 Figure 11: Holy side-panels Batman!............................................ 38 Figure 12: Typical Stub-axle ....................................................... 40 Figure 13: Axle Beams ............................................................... 41 Figure 14: Rear Axle Assembly.................................................... 42 Figure 15: Steering mechanism (one axle).................................... 45 Figure 16: Drive Assembly.......................................................... 51 Figure 17: Driveshaft detail ........................................................ 52 Figure 18: Partially assembled. ................................................... 56 Figure 19: "Discrete" Joystick principle........................................ 69 Figure 20: Analogue Joystick Principle. ......................................... 69 Figure 21: Open-loop relay-controlled steering. ............................ 71 Figure 22: Z-Bracket.................................................................. 72 Figure 23 Overview of Closed-Loop Position Control. ...................... 73 Figure 24:Steering/Drive Mixing. ................................................. 74 Figure 25: Electronic Differential Using 4QD Controllers.................. 75 Figure 26: Characteristics of lost-motion device. ........................... 76 Figure 27: When it comes to heatsinks for MOSFETS, one from an old

PC can't be beaten... ............................................................ 77 Figure 28: Forward/Reverse Relays (single motor shown)............... 80 Figure 29: Typical Characteristics of Wiper Motor........................... 83 Figure 30: Pulling Force vs Speed. ............................................... 84 Figure 31: Achievable Gradient vs Speed...................................... 85 Figure 32: Pulling Force vs Speed for Different Ratios .................... 86 Figure 33: System with poor drag................................................ 86 Figure 34: CG position, EMPTY .................................................... 88 Figure 35: CG position, DRIVER only............................................ 89 Figure 36: Illustration of lateral tip angle...................................... 92 Figure 37: Position of CG............................................................ 93 Figure 38: Forces on Motor ......................................................... 95 Figure 39: Simple mounting bracket. ........................................... 96 Figure 40: Oval holes allow for movement. ................................... 96 Figure 41: More complex bracket................................................. 97

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Figure 42: Detail of parental override module. .............................100 Figure 43: This sound module came from a toy tractor..................102 Figure 44: Components of Prototype Crane..................................104 Figure 45: Components of Original Crane. ...................................105 Figure 46: Section View of Crane Column ....................................107 Figure 47: Motor Mount.............................................................109 Figure 48: Boom Lift Detail ............... Error! Bookmark not defined. Figure 49: Crane Capability........................................................111

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Acronyms & Abbreviations

The following acronyms and abbreviations are used in this document:

Acronym/Abbreviation Intended Meaning

A Amps

Centimetres cm

CO Changeover

Deg. Degree

e.m.f. Electro-motive force

Fwd Forward

φ Diameter

g Acceleration due to gravity.

kg Kilogramme

l Litre

m Metre

mm Millimetre

mph Miles per hour

N Newton

NC Normally-closed

NO Normally-open

N.m. Newton-metres

PAR Planed All Round

r Radius

SP Single-pole

THRU Through

Typ Typical

V Volt

WBP Water Boil Proof

Table 1: Acronyms & Abbreviations.

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Conversion Factors.

The following conversion factors are provided as a quick-reference:

From To Multiply by

mm 25.4

cm 2.54 Inches

m 0.0254

m 39.37007874

cm 0.393700787

mm

Inches

0.039370078

Kg lbs 2.204622622

lbs Kg 0.453592370

N.m lb.ft 0.737562147

lb.ft N.m 1.355817952

Table 2: Conversion Factors

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Contact Details:

This document was authored by: Hugh Neve

E-mail: [email protected]

Please read the documentation before attempting anything similar and re-read it before contacting me with any queries.

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Revision History

Revision Date Change Reason for Change.

- JUL 06 - Initial Issue

A AUG 06 Various. Update to include Perspex windows,

modified tailgate, etc.,

Table 3: Revision History.

Configuration Data.

Document Generation MS Word 2000 9.0.2070

PDF Generation deskPDF n/a

Image manipulation MS Paintbrush Version 5.1 SP2

Image location OLE Insertion

Document location C:\STOLLY\

JollyStolly


1 Introduction. JollyStolly is a child-size homage to the Alvis Stalwart, a six wheel drive all-terrain amphibious supply transporter that was designed in

the 1960s, when it was thought that military supplies could have to be transported across the lands and rivers of Germany in the even of a third world war. Thankfully, it was never needed in this role: its high

fuel costs and advances in helicopter technology eventually made it redundant.

As homage, it is a tribute to the design and engineering skills of Alvis

and the personnel of the British Army who drove and maintained them. There is no connection to the Alvis product and the JollyStolly is

not intended to carry large quantities of ammunition or jerry-cans through central Europe! This document describes how I made a battery-powered two-wheel

drive “JollyStolly” to transport one or two children, and is a guide to repeating this if you wished to. The JollyStolly was born out of an enthusiasm for an ‘interesting’ toy

for my children and a need to keep up with the shiny, chrome and

plastic toys that their peers enjoyed. If I was four years old, would I want a shiny pink VW Beetle, or a four-wheel drive with big balloon

tyres, or, as I suspected, would I go for something that looked that part and that no-one else had? I knew what the answer would be and,

since an Army open-day in 1974, I knew that it would be a Stolly…

It took six months worth of working over weekends and/or waiting for parts and/or re-working for the prototype, “0001”, to move under its

own power. Lots of lessons learned have been incorporated in these plans, which have been designed to make the process as easy as

possible and, above all, fun! However, as there are no such things as ‘standard’ parts, you also get the challenge and fun of tweaking things

to fit the parts that you can obtain.

This manual is presented in a reasonable logical order. It is suggested

that you read it all before thinking about making one…

Enjoy!

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2 Description The JollyStolly is constructed from wood, with a small amount of steelwork: the body is constructed from 9mm Exterior plywood, glued

and screwed together after being cut to size. Some planed timber is used to strengthen the body, with sheets of corrugated roofing material used to give the look to the sides and tailgate.

The body is grain-filled with filler, primed and painted.

The front and middle sets of wheels rotate on steel stub axles that

pivot on the ends of box-steel beam axles. These wheels are those that steer and the steering-arms are motored in each direction by rods

connected to arms on a torque-rod. This torque rod is turned through the action of an automotive wiper-motor. The rear pair of wheels are the driven wheels. Each wheel is driven by

an automotive windscreen wiper-motor, with final reduction effected via chain-drive. The JollyStolly is controlled from the ‘cab’, in which the driver sits.

Control of the prototype is via a joystick, which commands both the

steering and the drive.

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3 Common Sense The JollyStolly was designed as a ‘fun’ project: fun to build and to use. But, like everything else in life, there are risks involved. The

construction inevitably involves sharp tools, and the operation involves small children and a powered vehicle. Common-sense should be used at all times!

The following construction and operation tips should be read before

commencing work. Not only do they provide safety tips, but the operational tips also explain some of the design decisions.

If in doubt, find a knowledgeable person who knows…

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3.1 General Techniques

During the construction phase it will be necessary to perform the

following operations, during which great care should be taken (also bear in mid that there may be lots of interest from ‘little people’, so take great care with keeping the working area clear of loose materials, tools, cables, hot objects, etc.):

3.1.1 Measuring.

• Measuring happens before any cuts;

• “Measure twice: cut once” is an old adage, but it is a very good

one;

• Try to include one factory-machined edge in each piece of plywood that is measured out;

• Use a pencil or fine felt-tip to mark plywood: this will be visible under the clouds of dust and sawdust during cutting;

• Cut plywood oversize and then sand it down to the measured size rather than end up with an undersize or splinter-edged piece

of ply;

Tip: How to find the centre of an arc given the radius and known lines of tangent:

Centre of arc, radius ‘r’

‘r’ from given line.

‘r’ from

given line.

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3.1.2 Sawing.

• Ensure that the material is well supported either side of where the cut will be made;

• Keep body parts away from the cutting edge;

• Be aware of where the cut will go – it is all to easy to cut

through a trestle with a saw;

• If cutting metal, ensure that at least three teeth of the blade will be present on the cut surface, i.e., change the blade if you change the thickness of material – thinner material = more teeth

per inch (TPI);

• A finer blade in a jigsaw gives a better quality, splinter-free cut

in plywood;

• Wear gloves and eye-protection;

3.1.3 Drilling

• Ensure that the material being drilled is secure – large torques

can result from drill bits exiting surfaces;

• Use a drill press if you can – these are available to fit power

drills for £20;

• Use high-quality drill bits where possible;

• Mark the material and (for metal) use a hole-punch to stop the drill bit slipping;

• Fast speeds for small diameter drill bits: slower speeds for large diameter drill bits;

• Use a pilot-hole where large drill bits are going to be used;

• Wear gloves and eye-protection and keep hands, hair and

clothing away from rotating parts;

• Don’t put too much pressure on the drill;

• ‘Piranha’ brand drill bits are highly recommended for drilling

metal: they drill on contact without skidding and complete the hole easily and cleanly, with a continuous spiral of swarf being

generated (rather than lots of chips).

• Swarf is sharp and can cut – clean it up and de-bur the holes

after they have been drilled;

• Remember to take the chuck-key out!

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3.1.4 Planing

• Planes have a very sharp blade. Get to know your plane, the way that the blades adjust and the adjustments that are required in

order to cut the material you are using in small, steady cuts;

• If you are able to, mark the limit of the cut on the material using

a ruler or a marking gauge on both sides;

• Keep your hands and body parts behind the plane;

• Ensure that the material is held securely;

• Keep the plane chute free of shavings;

• To achieve a specific angle use a sliding bevel to transfer the angle from one surface to the other:

If A-A’ is the first measured line on one surface, use the sliding-

bevel to mark out A-B and A’-B’ to allow B-B’ to be drawn. All of these lines can then be used to achieve the correct angle.

3.1.5 Sanding

• Sanding makes lots of unhealthy dust: wear a mask and eye protection to keep it out of your body;

• Use extraction facilities where they exist;

• Avoid dust-traps than can become fire-traps;

• If sanding by hand use a sanding block: a scrap piece of wood

will do – as long as it is flat and smooth;

• Start with the coarser grades (smaller grit numbers) and then progress to the finer papers (bigger grit numbers);

• If using a sanding machine, use the extraction facilities.

A

A’ B

B’

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3.1.6 Grinding

• The material to be ground should be securely held;

• Wear gloves and eye-protection: cutting/grinding blades make a horrible wound that is very difficult to stitch, and they do that cutting very quickly;

• Keep the filings (the sparks) going away from you where

possible;

• Work at a slow and steady pace – don’t rush the cutting or

grinding or the blade will get to hot and may shatter;

• Don’t grind aluminium or aluminium alloys – the disc might

shatter;

• Once a cut is started keep it going or stop – don’t try and

change the direction of the cut – the blade might shatter;

• Start and stop the machine with it held away from the material, not in contact with it.

• Cutting discs (flat) are for cutting, NOT grinding;

• Grinding discs (cupped) are for grinding, NOT cutting;

3.1.7 Welding

• Secure the material before you start – bear in mind that it will get very hot and there will be lots of splatter;

• Bear in mind that there may be movement as the materials cool if they are not secured properly. Use clamps, etc., accordingly

• Protect yourself with appropriate gloves and eye-protection;

• Protect others by keeping them out of the way (especially from

the light of an arc, which can cause eye-damage);

• Clean the surface of the metal with de-greaser (brake cleaning

spray from a motor-factor is good if the surface is not hot) and

grind/file it to a bare metal surface;

• Ensure there is a good electrical bonding to the materials being

welded;

• Keep progress steady and the weld-pool a constant size.

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3.1.8 Joints in Wood

• Lots of plywood-to-plywood joints are made in JollyStolly. These are crucial to the strength of the finished product;

• Make sure that there are no gaps between the pieces being joined: some small gaps will be taken up during joining, but it is not a miracle cure.

• Plywood is produced with a small layer of wax on the outer faces

that stops the sheets sticking together in transit. This needs to be sanded off before a decent joint can be made;

• Screws need a pilot-hole, which should be just big enough to allow the shank of the screw to pass through, but not large enough that the load is taken by the head of the screw. Without a pilot-hole the two pieces of material will not be clamped

together, merely kept in ‘loose formation’;

• The screws should be ‘steered’ to keep them in the middle of the ply that the drilled piece is being joined to.

• Some modern screws have ribs on the head that perform the task of countersinking the screws very efficiently: other screws

may need countersinking in order to get a flush joint.

• Some DIY stores market boxes of screws with a driver-bit

included: these provide excellent grip and reduce the likelihood of screws being dropped and lost;

• If it is indicated in the instructions use clamps and props to keep items in the correct relative position. These can include clothes-

pegs (ask first!), masking tape and heavy weights.

• Keep sawdust and shavings out of the joint and apply waterproof

PVA glue on the mating surfaces. Don’t be shy of ‘topping up’ the glue-line if the glue is completely absorbed;

• Excess glue can be removed with a damp cloth before it dries:

generally speaking it is dry when it becomes transparent, but check the manufacturers directions;

• Don’t disturb the joint until the glue has completely dried – no matter how keen you might be;

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Good.

Tight joint with no gaps

Poor.

Gaps make for weak joing and poor glue-line.

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Good.

Screw has been guided properly and will lead to a secure joint.

Poor.

Will result in splitting/splintering.

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3.1.9 Batteries.

• Lead-acid batteries are (not surprisingly) full of acid and very heavy;

• Don’t drop or tip the battery – it may split and/or leak, or bruise your toe;

• Be careful when charging the battery – hydrogen is liberated and it is highly explosive;

• Don’t connect the charger with it switched on – connect it then switch it on;

• Keep the battery well secured in the JollyStolly;

• Clear up acid spills carefully – keep acid away from skin, paint,

chemicals, etc.,.

3.1.10 Chains and Sprockets.

• Sprockets have teeth: they can bite. Once something is caught

in the teeth of a moving sprocket it will be crushed between the teeth and the chain and kept there until it is spat out when the

sprocket has turned. This might be your finger, hair, tie, or anything else that gets near it.

• KEEP OBJECTS & BODY PARTS AWAY FROM MOVING CHAINS.

• Common sense says that if you are working on/near the chains

and sprockets it is prudent to ensure that they can’t be put in motion by a curious onlooker, wiring short, or accidental

movement as you peer in. Take the fuse out; switch the master switch off; unplug electrical connectors.

• In order to install chains it is necessary to make them up from the free length in which it is supplied. This can be achieved by

punching out pins with a hammer and small drift, or a friendly

cyclist can be persuaded to lend a chain-splitter.

• Repair-links are available to allow the chain to be joined more

easily than re-inserting the pins.

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3.1.11 Spray-painting.

There are three golden rules for achieving a good finish using spray-

paints:

a) Move the can at a constant speed and a constant distance from the object being sprayed.

b) Make sure that the can is moving when spraying starts and stops. This avoids ‘blobs’ of more dense spray at the beginning

and end of each pass. c) Build the paint in thin overlapping passes.

Constant speed. Varying speed.

Spray started/stopped Spray started/stopped when can moving. when can stationary.

Good Bad

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3.2 Operation.

The JollyStolly has bags of oomph, even if it moves very slowly: it is more than capable of putting dents into cars, knocking down fence panels, squashing bystanders against walls and causing havoc. Think about installing the radio-controls for parental-override (see APPENDIX

G) and always supervise it being used. Specific hazards include:

• the risk of others being crushed by the vehicle; • the risk of the vehicle passing under an obstruction that then

impinges on the driver; • the risk of the tailgate swinging onto shins; • the [low] risk of overturning;

• the [low] risk of fire;

It is pretty stable (as detailed in the Appendix E), but care should be taken on slopes and gradients, particularly making turns whilst going down slopes and gradients. Consider a tilt-switch to cut off the drive if it tilts too far if you think it might be used on uneven ground.

The original Stalwart floated: this one does not. It is not designed to go anywhere near water of any kind and will not like it if it gets wet. In deep water it will sink.

The controls are designed to be such that drive and steering stops when the controls are released – make sure that they can’t jam in a ‘drive’ condition.

JollyStolly


4 Materials / Other An outline bill of materials is listed in Appendix A. Most of these materials are readily available from builder’s merchants and the larger

DIY stores. Others are less readily available and need to be sought via the internet etc.,

eBay is an excellent source of materials at low prices: the wiper motors in the prototype were won on eBay for less than £2, plus a few

pounds P & P. They are also available from automotive breakers and salvage yards for £10 or so.

RS Components have a wide range of bearings and other mechanical

equipment, though a trade account is needed to purchase them. The only ‘professional’ assistance required in the construction of the prototype was the machining of the drive-shafts. Having bought the

materials from a steel stockholder the turning was done very cheaply and quickly for £5 beer-money by an old-timer at a local engineering company.

Unless otherwise indicated crimped connectors are the preferred

means of effecting electrical connections: the motors take large currents that might melt lesser connections. Various grades of cable

are available from motor-factors and electrical/electronic outlets. Kits that include a variety of connectors and crimping pliers are often

available at ‘Pound-shops’ and tool stalls at markets and car-boot sales, etc.,

Part of the challenge of the build is finding the parts and making

changes in the detailed design to accommodate minor changes, etc.,

One of the key items to procure are the wheels: the ones listed in the Appendix are slightly over-scale, but of the ones that were readily

available these were reasonably priced, had tread and plain-bore hubs. As supplied the bore of the hubs are too large and the adaptors

supplied must be used. This is not ideal, and impacts upon the design

of the transmission.

JollyStolly


5 Building Sequence This sequence is ordered to promote and assist the ease of construction. It does not, however, have to be followed religiously.

5.1 Hull

The hull is a logical place to start as it is relatively simple and because

it holds the cab and the mechanical components together. It introduces the jointing techniques before tackling the cab, which has some “interesting” compound angles.

5.1.1 Components.

1) Measure, re-measure and cut-out the following panels:

• Forward bulkhead; • Aft bulkhead; • Hull sides, (2 off); • Hull base;

• Hull aft end-panel;

• Hull forward end-panels;

5.1.2 Procedure.

1) Drill the hull sides and the hull base with a series of pilot holes

4.5mm from the edge and 30mm apart;

2) Clamp the first hull side in a vice/workbench so that it is up-

side down with its measured-out shorter length horizontal;

3) Position the aft bulkhead so that it:

a. is perpendicular to the hull side; b. has its mid-thickness line aligned with the pilot holes in the

hull side; c. the corner of the aft bulkhead is aligned with the

measured-out line of the hull side.

These are shown in the following figure.

�

JollyStolly


Figure 1: Alignment of hull-side and bulkheads.

4) Glue and screw the two pieces together.

5) Take the hull side out of the clamp/workbench and let the bulkheads sit on the workplace.

6) Using the criteria in (3) fix the other hull side;

7) Fit the mid and forward bulkheads by repeating (3) and (4);

Align bulkheads to this edge

90 Deg Typ

JollyStolly


8) The next task is to plane and sand the lower-edges of the hull

sides to be straight, level with (and parallel to) the lower (shorter parallel edge) of the bulkheads. By aligning the corner of the bulkheads with the measured-out edges of the hull sides these lines can be used as a reference.

By carefully machining the edges of the hull sides to meet these conditions the hull sides are made ready to accept the drilled hull base.

Figure 2: Trimming of hull-sides.

Trim this face level with bulkheads

JollyStolly


9) The hull base is fixed to the hull sides and the bulkheads by

gluing and screwing, with care being taken not to let the hull-sides bow during the process.

10) The longest edges of the base can now be planed and sanded so that they are flush with, and parallel to, the hull sides.

Figure 3: Faces of base that are required to be trimmed.

Plane flush

to sides

JollyStolly


11) You should now have something that looks like Figure 4, below. It can be placed the right way up and a straight-edge

used to draw a line along the inside of the hull-sides level with the top of the bulkheads.

Figure 4: Part-Assembled Hull

12) Repeat the planning and sanding until these top edges are level with the lines drawn in (11).

The panels that complete the front of the hull have – as noted on the

drawings – to be cut slightly over-size and trimmed to an appropriate angle using a plane and/or sanding after gluing and screwing in place.

The rear panel can be fitted after the end-faces of the hull-sides and the end of the base are planed level.

Mark this line (TYP)

JollyStolly


13) Fit the rear end-panel.

14) Fit the forward end-panels.

That is the basic construction of the hull completed…

This face of the base must be planed level with the

hull-sides to allow the rear panel to be fitted.

These faces need slight tweaking.

JollyStolly


5.2 Load-bed.

The load-bed sits above the hull and is where the ‘cargo’ (or second

passenger) is carried. It contains two access panels (to allow access to the transmission and electrics) and a drop-leaf door at the rear for access etc., It remains completely removable for maintenance.

5.2.1 Components.

Measure, re-measure and cut the materials for the following components:

• Load-bed base; • Load-bed panels; • Load-bed framework; • Load-bed side panels;

5.2.2 Procedure.

1) On a flat working surface glue and screw the two layers of the

load-bed base together, ensuring that they are flat and properly aligned. The screws should be placed from the side that will be

uppermost in operation.

2) It may be necessary to carefully grind or file away any screw-points that have punctured through the lower layer – if you haven’t screwed both layers to the dining table…

3) Assemble the sides by gluing and screwing the side-panels and framework together, ensuring that they are un-warped and

square. The framework and the edge of the panels should be flush.

4) Use glue and 40mm screws through the bottom panels to fix the sides to the bottom panels.

5) Use glue and 40mm screws to fix the front panel to the framework of the side panels, ensuring that the edges are flush

and square.

6) Further framework and plywood panels form the boxwork at the rear of the load-bed. These are capped with small offcuts of

plywood, screwed and glued in place.

7) The rear door is made from plywood and timber framework and

is hung on a pair of hinges. An installation tip is to drill holes to accept the head of the machine-screws in the ‘closed’ position.

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8) The edges of the access panels are given a 5mm radius using a

router and pop-rivets are fixed into blind-holes around the edge to give an ‘industrial’ look.

9) The corrugated sides are manufactured from ‘mini-profile’ roofing sheet. Whatever this is made of it is a blighter to cut: a

jigsaw shatters it; scissors can cause it to crack; knives can go ‘off-track’ easily. I have found that repeated light scoring with a

very sharp knife – led against the edge of a metal rule – can be quite effective, but some practise cuts are a good idea.

10) The corrugated sheets are pop-riveted to the ply of the loadbed sides: a φ3.2mm hole is drilled through both the

corrugated sheet and the ply and the rivet set.

11) Before the access panels are placed in position it is an idea

to run a continuous bead of black silicone approx 20mm from the edge. This can be left to cure and will form a good watertight seal when it is in position. Leave it for several days to ensure

that it has fully cured or it will end up sticking the access panel shut.

The tailgate is built up from 9mm WBP ply and 22mm battening as

per DWG 026: the dimensions should be double-checked before cutting to take into account any differences in sizes. The recess can

then be fitted with corrugated plastic as per the loadbed sides,

above.

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5.3 Cab

Before attempting the cab it is an idea to take a deep breath, send the family to the cinema, take the ‘phone off the hook and have a beer –

this is the most complex part of the assembly due to the compound angles involved. Don’t worry – any mistakes or inaccuracies can be ‘eased’ by sanding and/or filling.

5.3.1 Components.

Make the components from plywood. Where indicated, these parts

include over-size portions that will be trimmed during fitment.

Figure 5: Cab Assembly.

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5.3.2 Procedure.

Measure and cut the following components:

1) Cab base (1 off DWG 012)

2) Cab sides (2 off DWG 010)

3) Cab front face (1 off DWG 009)

4) Cab roof (1 off DWG 011)

5) Cab rear (1 off DWG 008)

6) Cab bead (1 off DWG 012A)

7) Screw and glue the rear bulkhead to the rear edge of the cab

base.

Figure 6: Cab base and cab rear-panel.

8) Screw and glue the front-face in place, using screws and glue

to fix the front-face and the base to the cab-bead.

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Figure 7: Cab base, rear-panel and front-panel.

9) Fix the right-hand cab side using glue and screws to fix it to

the rear panel, the base and the front panel.

Figure 8: Cab after fitment of right-hand side-panel.

10) The left-hand-side panel can now be fixed in a similar manner

to the right-hand side .

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Figure 9: Cab with front, rear and both side-panels in place.

11) The cab-roof can now be screwed and glued in place, ensuring

that any overhang is at the rear.

12) The edges of the panels can now be planed flush with the

adjacent panels.

13) The seat is fashioned from a rectangle of plywood suspended

from the base of the cab via short lengths of 50 x 25 PAR timber.

Figure 10: Seat added to cab.

50 x 25 Battens

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14) Now is the time to measure and mark-out pencil lines 10mm

from the edge of all of the windows. Using a 10mm spacing, drill φ3.2mm holes all the way around and fill them with pop-

rivets. (Note: you will need a couple of hundred, so don’t buy them in packets of 25 from a DIY shed – buy a box of 200 from

a motor factors, fixings specialist etc.,)

Figure 11: Holy side-panels Batman!

Plane flush

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15) The windows are ‘glazed’, either with 4mm exterior ply cut to size/shape and glued to the inside the cab, or by polycarbonate sheeting – sprayed with matt black paint on the inside and cut to shape before sticking in place with black silicone.

Notes: • It is easy to check the consistency of the spray painting –

hold it up to the light.

• The polycarbonate sheet has to be cut in straight lines: score once with a sharp blade, then snap-off over an edge.

16) The front ‘bumper’ is made from 50 x 25mm hardwood which is

secured to the base of the cab via blocks of timber or proprietary brackets. The joints in the corners of the bumper are mitred and the ends are chamfer: this bumper is going to

take a few knocks, so it is worth taking time to get it right. The gap between the bumper and the panels will be filled with filler.

17) The edges of the panels can now be planed and sanded flush

with adjacent panels in the same way that the hull panels were treated.

18) I added a length of 15mm pipe lagging round the opening, kept

in place with cable-ties passed through small holes.

That is the cab complete!

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5.4 Metalwork.

5.4.1 Stub Axles

1) The four stub-axles are constructed from the components

shown, namely a length of φ25 round bar drilled with φ10 and

(optional*) φ5 holes. These holes most be perpendicular and

through the diameter of the round bar – not offset. Redesign them if you use different wheels than the ones listed!

2) A 25mm steel washer is welded to the round bar to act as a bearing-surface for the wheel. This too has to be perpendicular

to the axis of the round bar.

3) A small piece of flat steel bar is welded behind the washer to act as a steering arm.

4) Following the manufacture of these components they can be put to one side until the other metal components are complete.

Figure 12: Typical Stub-axle

Split-pin

will fit here

10mm

bolt will fit here

Track

rod will fit here

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* A jubilee clips is a good alternative!

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5.4.2 Axle-beams

The two axle-beams perform several functions and hence need

accurate manufacture: they support the stub-axles – taking the loads from the wheels and allowing the wheels to steer – and aligning the torque-rod that will effect the steering.

The axle beams consist of 40mm steel square tube that is cut and drilled at either end and the middle before having lengths of drilled flat steel bar welded to the front and back

1) Having drilled the two φ10 holes, the ends are shaped by cuts at

45 Deg to the sides, followed by grinding or filing to achieve a rounded shape.

2) The pieces of flat bar are welded to the sides, ensuring that they

are securely clamped in place to avoid them moving during or directly after welding.

3) The mounting holes for the pedestal bearing can now be drilled

and de-burred.

4) These two components can now be placed to one side until the

rear axle-beams have been completed.

Figure 13: Axle Beams

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5.4.3 Rear axle-beams

The rear axle-beams have to be able to perform quite a few different

tasks, such as:

• Supporting part of the weight of the vehicle; • Keeping the geometry of the transmission correct;

• Transmitting the drive from the wheels to the vehicle;

To do this – and remain easy to manufacture – the design is a compromise. That drawn works in the prototype but can be tweaked or

re-designed to suit personal preferences and variations in the drive / transmission.

The beams themselves are constructed from 40mm square-section steel tube, cut to length with drilled pieces of flat steel welded to the side at the angle of the side of the hull.

Opposite corners of the square section are cut away with a hacksaw to enable M6 nuts to be welded into position: these are held in the correct position during the welding by using a piece of thick card (yes, it will burn!) through which two M6 bolts are placed. These bolts are

placed according to the position of the mountings for the outboard bearing.

Short lengths of 20mm square-section tube are welded to the bottom

of each axle: this completes them and they can be added to the pile of ‘completed metalwork’.

Figure 14: Rear Axle Assembly

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5.4.4 Driveshafts.

The driveshafts as drawn correspond with the installation as drawn

and the wheels as specified. In the event that any changes are made to either of these the design of the driveshaft will have to be changed

accordingly. The driveshaft has a step in diameter that must be machined – this is where access to a lathe is required. This step is necessitated by the

bearings used in the rear-axle (they are very flat, but only available to φ20mm) and the inner diameter of the wheel hub (adapted down to

25mm with the inserts supplied with them.

A friendly engineer or hobbyist can be bribed into performing this work: while they have it, ask them to machine the drive-sprocket and end-bolt, with a woodruff key in both sprocket and driveshaft. The

alternative is to perform some very careful welding with the driveshaft in-situ…

Once back from machining the φ20mm portion of the driveshaft will fit

very snugly into the holes of a ‘folding workbench’, allowing a pre-drilled washer to be welded onto the driveshaft and the weld carefully

ground back. The hole for the drive-pin can be drilled, ensuring that the driveshaft is securely held in the correct position.

The driveshafts can be placed to one-side: they do not require any

painting.

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5.4.5 Finishing.

The completed metalwork should be cleaned of splatter, rust and dirt.

This can be achieved using a manual wire-brush or a stripping disc in an angle-grinder TAKING GREAT CARE AT ALL TIMES. The bare-metal can then be de-greased and painted using Hammerite or other proprietary metal paint. This should be applied to all surfaces –

including internal faces (where they can be reached). Threads should be kept free of paint. Parts can be supported by, or suspended from, pieces of wire during

the process to avoid getting paint over the hands.

One of the characteristics of these types of metal paint is that the first coat forms a homogenous layer and then leaches small quantities of vapours for many months as it cures fully. If the paint instructions

indicate that a second coat is required it should be applied soon after the first in order to become amalgamated into a single ‘skin’. A second coat applied at a later date may become affected by the vapours of the first coat unless several months have passed.

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5.5 Steering Gear.

5.5.1 Description.

The steering is active on the foremost four wheels. Electrical

commands result in movement of a sprocket fitted to a wiper-motor. Via further chain-transmission this movement is reduced to impart

large torques to a ‘torque-rod’ that runs along the forward portion of the hull – running in bearings fitted to the beam axles.

As the torque-rod rotates it moves arms to which steering-rods are

attached via spherical rod-end bearings. The other end of the rods are attached to the steering-arms on the stub axles to move the wheels.

It will have to be designed and made to suit the detail of any particular installation. The forward arm attached to the torque-rod is greater in length than

the aft arm. This results in the middle pair of wheels moving by approximately 50% of the amount that the forward pair of wheels move.

Figure 15: Steering mechanism (one axle)

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5.5.2 Process.

The following process should be followed to install the steering gear:

1) The torque rod is manufactured by welding suitably cut and

drilled pieces of flat bar to the main rod.

2) The drive sprocket is, ideally, drilled to suit the diameter of the torque-rod and secured with a woodruff key and end-bolt. However, this requires professional machining and it would be acceptable to weld it on – if it can be achieved without melting

the pedestal bearing (which has to be fitted first) and it is square and concentric;

3) Mark-out the left-hand hull-side with shape shown in DWG 24, in

the positions shown in DWG 004;

4) Cut-out the marked hole using a padsaw/jigsaw – using drilled

holes at the corners if required. The hole should be finished with a rasp or file;

5) The un-equipped forward and mid axle-beams can be slid into

position in the hull and secured to the hull base with bolts through the flat bar: the bolts should be ‘head-down’, fitted with

washers and secured using lock-nuts;

6) The torque-rod for the steering can be slid through the hole in the mid bulkhead and the pedestal bearings fitted to hold the

torque-rod in place.

7) The stub-axles can be fitted to the beam-axles using 10mm

bolts, locking nuts and washers. The bolts are fitted ‘head’ up, with washers placed as required between the top of the stub-

axle and the beam-axle in order to ensure the steering-arm of the stub-axle can swing into the slot when under load.

8) The rod-end bearings can be fitted to:

a. Front-left stub-axle

b. Front-right stub-axle c. Mid-left stub-axle

d. Mid-right stub-axle e. Front arm of torque-rod

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f. Rear-arm of torque-rod.

9) The torque-rod should be constrained to the neutral position

(this depends upon the steering implementation – See APPENDIX B) and the front and mid wheels should be set to be parallel to

straight-ahead. This can be achieved by deflating the tyres and securing the wheels against a length of timber, etc.;

10) The distance between the pairs of rod-end bearings should

be measured. Lengths of 6mm threaded-rod should be cut to 10mm longer than this value and threaded into the rod-ends so that the wheels and torque-rod remain in the ‘straight-ahead position. This requires that one rod-end bearing of each pair is

removed to insert the threaded-rod.

11) Removing the constraints on the torque-rod and wheels

the drive-sprocket can be turned by a (gloved) hand to verify that the wheels move in the same direction and that the forward

wheels turn more than the mid-wheels. Movement should be free and smooth.

12) The steering motor should be installed (with consideration

to APPENDIX F) so that the motor-sprocket is aligned with the sprocket on the torque-arm;

13) If the pedestal bearings used do not allow for the

longitudinal movement of the torque-rod to be constrained (via a grub-screw, etc.,) collar-clamps should be fitted either side of one of the pedestal bearings.

14) The electrical/electronic portion of the steering control

system can now be installed (i.e., limit-switches, feedback sensor, etc.,)

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5.6 Drive and Transmission

5.6.1 Description.

Drive is effected through the torque produced from two windscreen-

wiper motors. These can generally be obtained from eBay or breakers/salvage yards at reasonable prices.

The motion and torque of the windscreen-wiper motors is transmitted

to the half-shafts via sprockets and chain. This reduces the speed and increases the torque. The two half-shafts each run in two bearings:

outboard bearings that allow rotation and axial movement; inboard pedestal bearings that allow rotation and fix the axial position.

Rotation of the half-shafts is transmitted to the rear wheels via substantial drive-pins and screws fixed into the wheel hub.

5.6.2 Design Considerations.

The installation of the transmission components will have to be tailored

to suit the wiper-motors that are being used. Suffice to say that:

• The design of the transmission is dependent on the wheels used:

those used for the prototype were sourced from Screwfix as wheelbarrow wheels. Any changes will propagate through the

design of the transmission.

• If the vehicle is required to reverse then the sprocket must be prevented from unscrewing on the thread of the wiper-motor. This opens up the possibilities for mounting the motors as they no longer have to be running in the same sense (i.e., both

clockwise or both anti-clockwise);

• Wiper-motors tend to run better in the direction in which they

were designed to run when installed in the donor vehicle – the worm gears have curved faces: if possible, install them so that

they run in that favoured direction when they are installed so as to propel the vehicle forwards;

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• It is a general rule of thumb, but wiper motors where the axis of

the motor is aligned with the rim of the gears are generally simple worm-gear reductions and don’t produce much torque. Those where the axis of the motor is more aligned with the output shaft generally have more torque to the multiple

reductions performed via vortex gears.

Not so good Better

• The axis of the pairs of sprockets must be aligned with, and perpendicular to, the axis of whatever they are fixed to: if not,

they will ‘wobble’ and stretch / break the chain.

Good Bad

• The teeth of both sprockets need to be in the same plane: if they are not lined up the chain will be strained and will eventually

break. Some form of constraint may be required to stop relative movement – if this is not built into the pedestal bearing shaft-

collars can be used.

Good Bad

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• Consider the use of a sprung chain-tensioner close to the driven-

sprocket to minimise slack and maintain tension.

• The chain will stretch under normal use and will require re-adjustment;

• The smaller sprocket has a small number of teeth: this means

that only a few teeth might be taking load at any one time – leading to skipping, wearing of the teeth and failures. This is

another reason for including a tensioner, which can also deflect the chain to increase the number of ‘active’ teeth.

Bad: chain only in contact for Good: chain in contact for

approx 120 Degrees approx 240 degrees.

• The chassis of the wiper-motors form part of the electrical circuit whether you like it or not: they were designed to be installed in

a negative-earth car with the chassis/mountings forming the return path in the circuit. If the two motors touch – either all the

time or when deflected under load - the control circuitry may be affected or a fuse blown.

• As the wiper-motor starts to move and apply tension to the chain a load of equal magnitude is being applied to the wiper-

motor. This tries to move the sprocket on the wiper-motor towards the sprocket on the half-shaft. This must be resisted by the mountings of the wiper-motor – the mountings must be designed accordingly. See APPENDIX F.

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Figure 16: Drive Assembly

• The mountings for the wiper motor (see APPENDIX F) should

minimise movement in all directions. Any slack that can develop in the chain under load will cause it to jump – leading to premature

wear of the chain/sprocket and really awful noise.

Drive

sprocket

20mm

pedestal bearing

Rear axle

Drive-

shaft

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The outboard ends of the drive-shafts are secured to the wheel by

screws into the wheel hub and drive-pins through both the shaft and the wheels.

Figure 17: Driveshaft detail

• If the drive-pin is too short and/or the ends of the drive-pin too

small there is a danger that it will bend and be ‘sucked-in’ through the hole in the wheel hub. Therefore, it is necessary to

use a very large cotter-pin or bolts/washers/nuts.

Hole for drive-pin

Holes for self-tapping screws into wheel hub.

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5.6.3 Procedure.

The following procedure should be followed to install the

drive/transmission:

1) The hole shown in DWG 024 should be marked out in the correct position on both sides of the hull.

2) The holes should be cut out using a padsaw/jigsaw (using drilled

holes at the corners if necessary) and finished off with a rasp/file. It is almost inevitable that screws have to be cut, so

think about using a metal-cutting blade, or unscrew affected screws before cutting.

3) A hole needs to be cut in the base of the hull to accommodate

the sprockets. A piece of plywood can be cut from 18mm

plywood directly or laminated by gluing two pieces of de-greased 9mm plywood together. This ply can be fixed over the hole in the base of the hull by screwing through the base having applied glue appropriately.

4) The rear-axles can be slid in through both hull-sides, to which

they can be bolted – the head of the bolts should be on the outside and washers and locknuts on the inside. The bolts should

be left loosely fastened.

5) The 20mm square-section strut can be welded to both rear-axles, ensuring that they are aligned in all directions. The bolts

can now be tightened and any protrusion of the bolts on the

inside trimmed off.

6) The pedestal bearings can now be installed in the hull, fixed through the 18mm plywood using washers and locknuts with the

bolts ‘heads-up’. The pedestal bearings should be packed with washers to ensure that their axis is concentric with the rear-

axle.

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7) The Igus bearings should be fixed to the outboard end of the

rear-axles: this is achieved using bolts that have been reduced in length. To do this, a nut should be threaded onto the bolt before cutting it and then the nut removed so that it cleans the cut portion of the thread as it does so. Packing washers might be

necessary between the bearing and the axle to ensure that the bearing is not deformed.

8) The wheels should be pushed fully onto the end of the driveshaft

and, by measurement, the distance between the outside of the hub and the drive-pin hole should be determined.

9) An L-shaped piece of wire (of the same diameter as the drive-pin

hole) should be made such that:

a. The shortest leg of the L is approx 20 mm;

b. The longest leg of the L is much longer than the value measured in 8, but marked with that distance;

10) By heating the wire to red-heat over a flame the wire can

be inserted into the hub of the rear wheels to the marked depth and the shorter limb used to bore a hole for the drive-pin. A

second hole can be bored in the same manner in a diametrically opposite position.

11) The rear wheels can be pushed onto the driveshafts and

self-tapping screws used to secure the driveshaft to the wheel. The drive-pin (or bolts) can then be fitted.

12) The driveshafts can be passed through the Igus bearing

and through the pedestal bearing. When the driveshafts are

flush with the Igus bearing the driveshaft can be constrained – either with shaft-collars or the grub-screw in the bearing.

13) The drive-sprockets can be fitted and the wheels spun by

hand to test the installation.

14) The smaller sprockets should be drilled and tapped to suit the thread of the wiper-motor;

15) The motors can be installed and the chains fitted.

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16) The chain tension and alignment should be checked, and it

should be verified that there is no electrical continuity between the chassis of the two motors.

17) As a precaution, the rear tyres should be deflated and

some silicone/rubber-cement smeared between the tyre and rim before refilling the tyres. This prevents the tyres slipping on the rim during more demanding manoeuvres.

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5.7 Assembly

Assembly of the components is straightforward and logical: the cab is attached to the hull with screws and glue; the bearers in DWG023 are fixed to the inside of the hull with screws and glue, and the loadbed fixed to the bearers with four 40mm screws countersunk into the

loadbed – these are easily undone to gain access to the hull. Careful measuring and re-measuring ensures that everything is symmetrical and aesthetically correct.

Figure 18: Partially assembled.

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5.8 Electrical.

The electrical installation is one of the final operations. It is, however, highly dependant on the exact design of steering / drive that has been chosen, so concepts have been included fairly generically.

Key points are: • Work to a plan - don’t just join-the-dots with the wiring,

however tempting it is to get on with it; • Pay attention to manufacturer’s recommendations with regard to

wiring length, proximity to other wiring, etc., This is especially important with microcontrollers and motor controllers;

• Switch the positive supply of the circuit – don’t leave ‘live’ wiring

and components floating round unless absolutely necessary; • Use the appropriately-sized wiring – inadequate wiring will melt;

• Use a consistent colour-code for the wiring and stick to it. If the more-readily available supplies don’t have sufficient variation consider motor-factors, auto-electricians or trailer suppliers (tow-bar electrics use 7- or 12-core cables using different

colours and available by the metre if you look hard enough, Maplins supply 7-core this way);

• Where possible label the wiring (individual wires or bundles as appropriate), using proprietary marking systems or a Dymo-

label; • Use insulated crimp connector is you can get them; • Always crimp connectors twice – once to make the electrical

connection and once to fix the connector to an insulated portion

of the connector;

• Use heat-shrink to insulate exposed wires (such as LED legs, etc). It is also useful for supporting sub-bundles – it binds the

wiring together and keeps it neat; • Do make allowances for removing/installing components and for

things to move/flex during normal use, but don’t leave loops of wiring where they can get tangled or caught in moving parts.

Make sure, for instance, that you can lift the plywood board and junction-box out in order to gain access to the steering gear;

• Support bundles of wiring using cable ties at regular intervals and anchor-points to guide the runs of the bundles;

• Don’t piggy-back too many connections – connect several terminal blocks together in the junction-box to allow more

connections to be made; • Test the wiring with a multimeter before applying power: bear in

mid that some fuse-holders have LED indicators which can ‘fool’

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a multimeter into thinking there is a connection; the current

from a multi-meter can also ruin delicate circuitry; • If you really want to, mount 12V LEDs into the top of the

junction box to indicate the state of various signals, switch positions, etc., This will make it look like an extra from a 1970’s

sci-fi film, but could be useful for troubleshooting. The first step is to plan the siting of the installation. The prototype used a rectangle of plywood mounted above the steering gear, resting

on angled bearers fitted to the mid and aft bulkheads. A 22mm hole allows a finger to be inserted to lift it out. A central-heating junction-box was then used as the means of making connections: this was relatively cheap, had the potential to make many connections and

included cable-clamps and cable-entries. This was fixed to the plywood board.

The battery has to be chosen and then installed: that in the prototype was rescued from an Alfa Romeo that a salvage yard were taking away

from my house. Car batteries are not ideal as they contain acid and are not suited to frequent deep-cycling. Deep-cycle batteries are

available for go-karts, golf-caddies, etc., and are often gel-based, which is inherently safer than the lead-acid versions – look on eBay!.

The battery is heavy and must be secured well. In the prototype, the battery was placed on top of two 38 x 38 battens that were screwed and glued to the bottom of the hull; the lower edge of the battery had

a series of 3mm holes moulded into it and these allowed the battery to be screwed to the battens. Be careful if using this approach: don’t puncture or weaken the casing of the battery or it could well leak acid. A ‘footman loop’ strap secured to the hull would be just as effective as

an alternative.

The battery is only connected to the drive-motor controllers and to one

point in the central heating box. These connections are via appropriately-sized fuses; all other supplies are via a fuse-protected

relay-supplied bus. The wiring is sized for the currents involved and all connections inside the junction-box are tinned using a soldering-iron.

The relay is commanded from a ‘master-switch’ that is mounted on the top of the junction-box (and thus accessible through the forward

access-panel) and a keyswitch. A large electrolytic capacitor is connected across the battery supply to the junction-box – this is

optional and is intended to stop the supply relay dropping out when load is first supplied.

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Eight-wire burglar alarm cable is used to connect the junction-box to a

forward-control box that houses a lighting switch, a key-switch and a horn button. The wiring from the joystick/command-device is led through the cab and hull to the junction-box.

Within the junction-box the wiring can be connected using the terminal blocks built into it – the pre-wired jumper-links will probably have to be re-configured.

The supply for the command signals (to the steering and drive) is via the switched supply: once this is switched off the vehicle is immobilised. Any permanent connections to the battery must be very small amperage to avoid draining the battery.

The final (optional) connection to the battery is a fused circuit between the terminals of the battery and a ¼” jack socket on the rear panel of

the hull. This allows a ¼” jack plug to be connected to a battery charger for easy charging without having to remove panels. This

socket could also be used to supply power to a trailer, etc., if required.

Rear-lights were implemented on the prototype using clusters of 12V LEDs that are available for information displays, etc.; the ‘headlights’

are the business-end of torches bought for 99p from eBay fitted with clusters of white LEDs soldered together. The wires are lead out of the back, the void filled with cotton wool and the wiring exit plugged with black silicone. The white LEDs had a voltage drop that meant six in

series (i.e., three per headlight) gave approximately 12V, so no resistors were involved. The horn was a piezo-electric sounder – effective, but not loud enough

so as to make too much noise and annoy the neighbours;

To meet ‘customer’ requirements another optional-extra fitted to the

prototype was an Action Man walkie-talkie base-station.

After checking the circuitry, and checking it again, the battery can be connected with all fuses removed. The main fuse can then be

connected and the operation of the switched supply verified. Once this is verified as working correctly, testing can commence…

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5.9 Testing.

The following should be checked/set-up before any testing commences:

5.9.1 Safety:

• Battery secured;

• Fuse(s) in place;

• Main switch OFF;

• Hull and cab free of tools, dust and shavings;

• Chains and sprockets are clear of wires, tools, debris, etc.,

• Full and free movement of the controls;

• Hull supported so that the wheels are free to rotate;

• Spectators well clear;

5.9.2 Tyre pressures

• Front tyres should be ‘firm’;

• Mid tyres should be ‘soft’;

• Rear tyres should be ‘firm’

(These ensure that the drive and primary steering functions are maximised, whilst allowing the mid pair to compress over any bumps –

otherwise the rear pair can be left spinning helplessly)

5.9.3 Steering function

• Check that the steering is smooth and in the correct sense across the maximum range of deflections;

• Check that the wheels do not touch the structure;

• Observe that the torque rod does not bend;

• Observe that there is no overheating apparent and that fuses remain intact;

• Check that cab area is not affected by movement of mechanisms etc.,

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5.9.4 Drive functions

• Check that the drive wheels move in the correct direction;

• Check that with the steering in the ‘straight ahead’/neutral

position the wheels turn at the same speed;

• Observe that no overheating is apparent;

• Observe that the fuses remain intact;

• Observe that releasing the control causes the drive to stop;

5.9.5 Combined Functions

• Verify any additional functions (i.e., electronic differential, etc) that have been included;

• Observe that the control (s) can be moved to all extremes in all combinations with full and free movement and without any overheating be apparent or fuses blowing;

5.9.6 Other electrical

• Check horn;

• Check lights;

• Check operation of parental override (if fitted);

Lower the vehicle to the ground and repeat the tests of steering/drive,

above, without a driver in place. If satisfied with the results, it can be tested by a test-pilot if required.

�

JollyStolly


5.10 Finishing & Painting.

The finishing and painting require effort: the more effort, the better the results will be. It is a matter of choice as to whether the insides of the hull and cab

are painted: if so, it should be done before the metalwork and electrics are installed! The first stage is to sand the entire area of wood to be painted,

concentrating on sanding flush the corners and edges. After removing the dust via vacuum and soft brush all cracks, crevices, screw-heads and joints can be filled with car body filler: this can be applied with a

flexible, straight-edged blade (an old credit- or store-card is ideal) and sanded flush. This process has to be repeated until a surface is

obtained that is smooth, both to the touch and when viewed by incident light. The car body filler also makes an ideal grain-filler to help to disguise

the plywood nature of the beast: I skimped and the grain seems quite obvious at times – when it is, I want to kick myself for being so lazy and impatient.

Having filled and sanded until the finest paper has been used and a smooth surface obtained the next step is to prime the areas to be painted. This includes the corrugated plastic, which can be primed with un-diluted PVA glue. Even un-diluted the PVA will bead and need

‘dragging-out’ with a brush as it dries – potentially needing several

coats. (Consider a spray primer if it can be tested on a scrap piece of corrugated plastic to verify it doesn’t melt it or flake off).

The primer used will depend upon the choice of topcoat used. The

prototype used ‘LandRover Green’ coach enamel. This, however, is very glossy and some matt “Nato Green” (BS3831 colour 285) would

be ideal. Colour code ‘7010-G70Y’ is a good match. Once applied, the primer should be sanded smooth and consideration given to a second

coat.

The top-coat can be applied according to the maker’s instructions, but should be allowed to cure before applying the ‘camouflage’ via matt

spray-paint. Don’t apply this too soon after application of the previous coat of paint or the spray-applied paint will crackle.

JollyStolly


The wheels also need painting. Read this now and consider painting them before they are fitted. The plastic of the hubs is particularly slippery and will require keying with some fine wet-and-dry paper, followed by some patient application of PVA glue/primer. Beading is

inevitable, so patience is required. Before the top-coat is applied, consider deflating the tyre to allow the hub to be painted without getting paint on the tyre: this approach is easier than trying to apply masking tape to a curved surface.

JollyStolly


APPENDIX A: Materials List

This list is not exhaustive and will have to be adapted to the final design that is adopted: it is provided as an illustration of the type of materials required and the quantities involved.

JollyStolly

Page 65 of 155

Rev B

© Hugh Neve 2006

Item

No

Description

Size

Quantity

Supplier

Part Number

1.

9mm Exterior (W

BP) Plywood

2440 x 1220

mm

2 sheets DIY

As Req

2.

18mm Exterior (W

BP) Plywood

Offcut

1 off DIY

As Req

3.

Square section steel tube.

40 x 40 x 3 m

m

1.5m

4.

Round steel bar

φ25mm

1.5m

5.

Flat steel bar

25 x 5mm

1.0m

Steel

stockholder.

As Req

6.

Steel washers

φ25mm ID

12 + DIY / Screwfix

As Req

7.

Steel washers

φ20mm ID

5 + DIY / Screwfix

As Req

8.

Waterproof PVA wood glue.

500 m

l 1 off DIY

As Req

9.

Screws

20mm

As Req (200+ DIY / Screwfix

As Req

10.

Planed timber, 38 x 38 mm

nom.

DIY

As Req

11.

Mini-Profile Corrugated roofing

sheet

1 off DIY

As Req

12.

Studding

M6 x 1m

1 off DIY

As Req

13.

Studding

M12 x 1m

1 off DIY

As Req

14.

Rod-end bearings

M6

8 off RS Components

689-401

15.

Wheels

6 off ScrewFix

20600

16.

Wiper motors

3 off

eBay / Scrapyard

17.

Pedestal bearing - driveshafts

φ20mm

or

φ25mm

2 off RS Components

339-8726

18.

Pedestal bearing - steering

φ20mm

or

φ25mm

2 off RS Components

311-2689

19.

IGUS flange bearing

φ20mm

2 off RS Components

311-2780

20.

Chain

6mm

1m Technobots

4216-001

21.

Chain links

6mm

2 off Technobots

4216-010

22.

6mm Sprocket

9T

2 off Technobots

4210-002

23.

6mm Sprocket

30T

2 off Technobots

4210-013

24.

Rear lights

LED 12V

2 off Maplin

Electronics

PD00A

25.

Junction box

As Req

1 off DIY

As Req

JollyStolly

Page 66 of 155

Rev B

© Hugh Neve 2006

Item

No

Description

Size

Quantity

Supplier

Part Number

26.

5-pin Automotive relays

30 A

As Req Technobots

1600-001

27.

Electrical flex

25 A 12 V

Motor Factors

As Req

28.

Electrical flex

5A 12 V

Motor Factors

As Req

29.

Jubilee clips

25mm

4 DIY

As Req

30.

Battery

40 A.hr

1 off Motor Factors

As Req

31.

Battery connector +ve

1 off

As Req

32.

Battery connector –ve

1 off

Motor

Factors /

Maplin

Electronics

As Req

33.

Automotive body-filler

1 kg Motor Factors

As Req

34.

Hinges

1 pr DIY

As Req

35.

Joystick

As Req eBay

As Req

36.

Primer

1.0l DIY

As Req

37.

Paint

1.5l DIY

As Req

38.

M10 Bolts

As Req DIY / Screwfix

As Req

39.

M8 Bolts

As Req DIY / Screwfix

As Req

40.

Draw-catches

2 RS Components

197-4126

41.

Pop-rivets

3.2mm

200 DIY

/ Motor

factors

As Req

“DIY” is a generic reference to DIY superstores / Ironmongers, etc.,.

JollyStolly

Page 67 of 155

Rev B

© Hugh Neve 2006

Vendor Contact Details.

Name

Website

RS Components

rswww.com

Maplin Electronics

www.m

aplin.co.uk

Technobots

www.technobots.co.uk

Wickes

www.wickes.co.uk

ScrewFix

www.screwfix.co.uk

B & Q

www.diy.com

4QD

www.4qd.co.uk

HPC Gears

http://w

ww.hpcgears.com/

Namrick fasteners

www.namrick.co.uk

Useful eBayers

(These are not recommendations or endorsements.

Exercise common-sense and caution, looking at their feedback, etc)

Seller Name

For…

“8fcl”

Gel Batteries

“motion_control_products”

Motors/gearboxes

“europrotrolleys”

Gel

batteries,

motors,

gearboxes, chargers, etc.

louisa2033

Paints

JollyStolly

Page 68 of 155

Rev B © Hugh Neve 2006

APPENDIX B: Steering Strategies

JollyStolly

Page 69 of 155


This Appendix details the possible methods that could be employed to

effect the steering. First is the choice of controller….

Choice of controls is driven by the needs for steering and drive implementation, as discussed in Appendix C, below.. If both steering and

drive are to be commanded relatively simply, via relays etc., then the controls can be relatively simple too. Choices of control include:

Joystick.

Advantages: Cheap, easily obtainable, can be used single-handed, doesn’t take up too much space in the cab;

Disadvantage: Not as intuitive as a steering wheel for small children; forces drive/steering systems to use the same sort of input

Joysticks for older home computers come in two flavours: the simpler

‘discrete’ type where contacts are made or broken as the joystick is moved.

A circuit is made between a common input and switches for North/South and/or East/West, with perhaps an extra connection or two for ‘fire’

buttons. North

East

Common South

West

Figure 19: "Discrete" Joystick principle.

In the analogue type position information is achieved via a potentiometer for North/South and another for East/West, with a discrete output for fire-

buttons. Usable types have 15-pin D socket connectors – if the connection is via USB or PS/2 then it probably won’t be usable without taking it to bits

and getting at the sensors directly.

+

North / South

East/West

Gnd

Figure 20: Analogue Joystick Principle.

JollyStolly

Page 70 of 155


Searching on eBay for Amiga or Atari joysticks will result in many possible

listings, starting at very reasonable prices. Look for clues as to the type of joystick in the listing, and if it is not clear ask the vendor for clarification.

There are quite a few wiring diagrams for joysticks on the internet, or the connections can be deduced using a multimeter or partial dis-assembly of

the unit to examine wire-colours (go on, you are tempted!).

The prototype used a joystick for drive and steering to good effect. However, there could sometimes be confusion as to which way the wheels

were pointing as there is no direct relationship between the position of the wheels and that of the joystick.

Steering wheel. Advantages: More intuitive, allows drive/steering signals to be split if they

are required to be of different types (e.g., on/off discrete for one and

analogue voltage for the other); Disadvantages: More complex signals to use, more difficult to implement,

takes up more room in cab, more expensive.

The prototype had a steering-wheel for a short while during development: the wheel (a handwheel from RS) was connected to a series of

microswitches that gave ‘left’, ‘right’ and ‘centre’ commands to the steering gear via relays. Moving the steering-wheel towards the user gave a ‘drive’

command (i.e., if the vehicle hit something and the user was thrown forward it would disconnect the drive). This three-position system did suit

the driving style of younger children (who only seem to use full-lock at any one time) but the microswitch assembly proved difficult to calibrate and to

make robust enough within a sufficiently small envelope. A lost-motion assembly (described below) allowed the ‘centre’ command to be routed to

the appropriate relay to allow the steering to be motored towards neutral –

it gave a modifiable ‘dead-zone’ to prevent the steering hunting either side of the neutral position.

JollyStolly

Page 71 of 155


B1. Open-loop Relay-controlled Electrical.

The simplest, if inelegant, implementation of steering control is as laid out

in this document use of a wiper-motor to turn the steering torque-rod. The wiper-motor is controlled in by simple off/on switched signals (an old

Amiga / Atari ST joystick from eBay is ideal). In the centred position no current is supplied to the wiper-motor: with the ‘left’ command current is

provided so as to move the wheels left; the reverse applies for a ‘right’ command.

When the torque-rod reaches its limit (the point at which the wheels

cannot be turned without rubbing on the structure) the associated command signal is interrupted by a microswitch opening. The

microswitches are mounted on ‘Z’-section aluminium brackets to allow adjustment of the limit position.

M

‘Left’

Command

RL1 RL2

RL1

RL2

-VE

+VEFuse 1

‘Right’Command

RL1

RL2

‘Left’ Limit ‘Right’ Limit

Figure 21: Open-loop relay-controlled steering.

JollyStolly

Page 72 of 155


Figure 22: Z-Bracket

B2. Hydraulics. Some observers of the prototype commented that the steering could be

implemented effectively through the use of ‘hydraulics’, with a motorised lead-screw advancing or retracting a pair of master cylinders, each linked

to a pair of slave cylinders – one pair for the front wheels; one pair for the middle wheels. At first glance this seems feasible but expensive: medical

syringes of different sizes have been mooted as a possible means of implementation. However, such a system is likely to be complex, messy,

and difficult to control. Given the losses in the system, anything capable of driving the master-cyclinders is likely to be equally up to the task of driving

the wheels directly.

B3. Closed Loop.

The implementation of steering control employed in this manual and in the

prototype is (apart from position switches) open-loop, in that the steering command can only ever be in one of three positions (‘move-left’, ‘do

nothing’ and ‘move-right’) and there is no feedback of the position of the wheels in the control loop.

Two possible alternatives allow for feedback from the steering mechanism

to ‘close the loop’ and allow for more precise control: both use analogue command inputs (a variable voltage from a joystick, steering wheel, etc.,)

analogue feedback signals (from a position sensor in the steering mechanism) and a control system.

JollyStolly

Page 73 of 155


The difference between the feedback and the command signals is used to generate an ‘error’ which, in turn, drives an H-bridge to drive the actuating

motor.

E.g., If the command voltage ranges from 0V (full left), through to 6V (neutral) to 12V (fully right), the feedback signal would be established to

range from 0V (fully left) to 12V (fully right). If the command is changed to 4.2V (left of neutral) and the wheels remain ‘straight-ahead’ there will be a

difference of -1.8V. This is rationalised into a voltage that stimulates the H-bridge in the direction to move the wheels to the left. As the wheels move,

the voltage from the feedback device reduces until the feedback voltage also equals 4.2V: the difference is zero and so the drive stops.

This is quite complex and issues of gain, dead-bands, etc., have to be

examined, but the decision making can easily be performed by an Op-Amp

or (for the more ambitious) a PIC controller (www.picaxe.co.uk, for example) – indeed, H-bridges with closed loop control and microcontroller

are available on one board (www.technobots.co.uk).

M

Command

Feedback

Comparator

‘Left’

‘Right’

+ve

-ve

Figure 23 Overview of Closed-Loop Position Control.

This principle is applicable to any drive method, but doubled-up it opens up

the possibility of separate motors driving the pairs of wheels directly.

JollyStolly

Page 74 of 155


B4. Drive-Augmentation.

The original plan for the prototype was to link a closed-loop steering system with a solid-state speed control system: the steering command

signal was to be used to slow the drive wheel on the inside of the turn. Using solid-state speed controllers the pulse-width modulation allows for

the speed to be reduced without such a significant reduction in torque.

The ‘golden standard’ solution might be a closed-loop system with direct drive steering to the pairs of wheels, linked to the drive via a

microcontroller to achieve the optimum steering angles at any given speed.

Control Input

Mixer

Slow

Fast

Drive command

Steering commands

Fwd

Figure 24:Steering/Drive Mixing.

JollyStolly

Page 75 of 155


B.5 Electronic differential.

If you have ever driver a Land Rover on tarmac with diff lock engaged you

will appreciate the need to have wheels on different sides of the vehicles travelling at different speeds. This is what the simpler on/off relay

controlled drive systems can’t achieve.

The prototype uses a system of differential steering that is not quite the ‘golden solution’ of the ‘drive augmentation’ method detailed above, but

that is quite effective in boosting the steering response. Two ‘Egret’ motor controllers are used to provide independent drive to each motor. When the

‘forward’ command is given, and if the steering is ‘straight-ahead’ the motor controllers proceed “full ahead, flank”. If the steering moves away

from the straight-ahead position a lost-motion device causes one of two microswitches to switch. The command voltage to the controller is halved

and the wheel on the inside of the turn rotates at (approximately) half

speed. This difference in speed reduces the scrubbing of the driven tyres and reduces the turning circle. The change in speed of the wheels is

dampened by the ramping inbuilt in the Egret controllers.

M

M

1

2

3

EGRET MOTORCONTROLLER -LEFT WHEEL

1

2

3

EGRET MOTORCONTROLLER -

RIGHT WHEEL

40A 40A

100K

100K

100K

100K

Open onleft turn

Open on

right turn

Drive

Drive

Figure 25: Electronic Differential Using 4QD Controllers.

JollyStolly

Page 76 of 155


The lost-motion device uses the hysteresis of the microswitches to ensure

that there is a ‘dead-zone’ either side of the straight-ahead position in which neither drive-command is changed. An arm fitted to the steering

torque-rod is connected to the levers of the microswitches via springs with the springs uncompressed in the straight-ahead position. As the arm

moves one spring compresses and eventually activates the associated microswitch; the other spring elongates and its microswitch remains un-

activated. As the arm returns to the straight-ahead position the springs return to their normal condition and the activated switch deactivates. In

the prototype the springs were ‘liberated’ from retractable ball-point pens and attached to the levers of the microswitches by tywraps. Changing the

position of the microswitches changes the tension in the springs and hence the size of the dead-zone: centring the steering and releasing the arm to

move freely correctly establishes the midline of the dead zone.

Figure 26: Characteristics of lost-motion device.

The obvious next step would be to make the change continuously variable

rather than step changes in speed. This was not implemented on the prototype because I felt that the steering mechanism didn’t have sufficient

spare torque to turn a dual-dang potentiometer as well as moving the

wheels, and this version works well enough.

JollyStolly

Page 77 of 155


Figure 27: When it comes to heatsinks for MOSFETS, one from an old PC can't be

beaten...

JollyStolly

Page 78 of 155


APPENDIX C: Drive Control Strategies

JollyStolly

Page 79 of 155


This Appendix details some of the methods that can be employed to control

the current being sent to the motor(s).

The first criterion is whether the JollyStolly is required to reverse or not: if so, the drive sprockets must be welded to, or otherwise fixed to, the

motors so that they don’t unscrew if the motor runs in a backwards direction. Having decided that, the drive-control strategy can be chosen.

Whatever implementation is used, the ‘command’ side will generally be low

current affairs at the front of the JollyStolly: this has to be used to control large currents passing from the battery (at the rear of the vehicle) to the

drive motors (in the middle).

C1.Relays.

Automotive relays are cheap, cheerful and easy to use. They can be rather

brutal in the nature of their switching since there is either ‘no power’ or ‘full power’, but, on the plus side, they are generally sealed against the weather

and capable of switching large currents using low current commands.

C1.1. Forward Only.

For a ‘forward only’ implementation, the negative supply can be permanently connected and one ‘three-pin’ (i.e., Single-pole NO) relay can

be used to switch the positive supply to each motor. Easy – it couldn’t be any simpler.

JollyStolly

Page 80 of 155


C1.2 Forward and Reverse.

To implement a solution that is capable of both forward and reverse motion, a pair of ‘four-pin’ (i.e., Single-pole CO) relays can be used to

determine the forward/reverse running, with a further ‘three-pin’ relay controlling the live positive supply: e.g., there needs to be a ‘drive’ signal

(0V = stop; 12V = go) and a direction signal (0V = forward; 12V = reverse). Figure C2, below, shows this circuit.

Note that this is dependant on the relays (‘RL2’ & ‘RL3’) having an identical

change-over time: if one lags the other a direct short occurs and the fuse will blow. A double-pole CO relay solves this problem very succinctly – if

you can find one that can take the current…

M

‘Drive’ ‘Direction’

RL1 RL2 RL3

RL1

RL2

RL3

-VE

+VEFuse 1

Figure 28: Forward/Reverse Relays (single motor shown)

JollyStolly

Page 81 of 155


C2. Solid State Controllers.

A number of excellent solid-state speed-controllers are available commercially (www.4qd.co.uk, has some excellent background reading and

supplies excellent products) or can be made by a proficient hobbyist.

In general, an H-bridge of MOSFETS are driven by electronic circuits that implement pulse-width modulation of the supply to the motors. This allows

smooth control over a wide range of speeds without the huge loss of torque associated to operating with merely a reduced supply voltage. ‘Nice’

functions such as a maximum rate of increase of speed, regenerative braking and user-configurable maximum speed are additional features that

suit the more common users of the controllers, e.g., golf-carts, caravan movers, etc. The smooth ramp-up eases the shock on the transmission

system.

These devices require a low (zero!) current voltage to be applied to the

input to effect control. This opens up the possibilities of drive-augmented steering discussed above, and precise, smooth sped control.

The trade-off for these advantages is that a lot of heat is generated by the

MOSFETS, which must be dissipated. The prototype used an aluminium heatsink and a cooling fan when solid-state controllers were being

considered. The smaller (cheaper) controllers use the battery to smooth the voltages induced by the ‘chopping’ of the supply: this limits the length

of wiring between battery and controller, which can constrain the design.

As well as the excellent information on the 4QD site, a wealth of information may be found on the internet to assist with the selection,

design or use of solid-state speed controllers: not only are they used for golf-carts, etc., but they are a basic staple of the robot-building hobbyist

and radio-controlled car fanatic.

(See the previous section for steering strategies involving these devices.)

JollyStolly

Page 82 of 155


APPENDIX D: Forces Involved.

JollyStolly

Page 83 of 155


D1. Introduction.

This appendix details an outline of the forces involved in the power-train of

the JollyStolly.

D2. Wiper Motor Characteristics.

There are various types of wiper motors available. The simplest ones have

a single worm-gear and gear-wheel arrangement and can only produce a relatively small amount of torque. The better types are those with two or

more vortex gears in the gearbox, multiply the torque many times, up to the level required in order to be a candidate for JollyStolly drive motors.

The torque/speed characteristics of a generic automotive wiper-motor are

shown in Figure D1, below. These were supplied to me by a far-

eastern supplier of these motors: I am extremely dubious and think they could a factor of five out at least, and I expected them to be

more linear!

The maximum torque occurs when the motor is almost stationary and about to stall: at greater speeds the torque is less (there is more back-

e.m.f. in the windings of the motor).

Torque vs Speed

0

5

10

15

20

25

30

35

40

45

0 10 20 30 40 50 60 70 80

Speed, rpm

Torque, Nm

Figure 29: Typical Characteristics of Wiper Motor.

The chain drive has a 5:1 reduction, which increases the torque, t, by a further factor of 5. The wheel diameter is known at 0.36m and there are

two motors. The reaction at the wheel edge can be calculated.

JollyStolly

Page 84 of 155


FT = 5t Newtons 0.36

Converting from Newtons to ‘kg’ through dividing by ‘g’, allows the plot B2

to be generated.

Pulling force vs Speed

0

20

40

60

80

100

120

140

160

0 0.1 0.2 0.3 0.4 0.5 0.6

Speed, mph

Pulling force, kg (N/g)

5:1 Ratio

Wheel slip (60kg mass, µ = 1.2)

Figure 30: Pulling Force vs Speed.

(Gross error check: 2 motors taking 12A @ 12 V = 288 W [no losses

through heating, etc.,]. At 0.5 ms-1, this equals 576 N (58.72 Kg force))

At very low speeds the friction between the wheel and the ground can be

overcome and the wheel will slip – assuming the welding and bearings hold out…

At higher speeds the torque runs out and there is much less ‘puff’. So, if

there is lots of friction to overcome in the transmission the speed will drop off until the available torque increases to match the friction: this is why it

is desirable to have low-friction transmission components.

For a total mass of 40 kg or 60 kg, the maximum gradient possible gradient can be calculated. This is plotted in Figure D3.

JollyStolly

Page 85 of 155


Gradient vs Speed, 5:1 Reduction

0

10

20

30

40

50

60

70

80

0 0.1 0.2 0.3 0.4 0.5 0.6

Speed, mph

Gradient, Deg

40kg

60kg

Maximum advisable slope

Figure 31: Achievable Gradient vs Speed

Again, in D3, friction isn’t taken into account and it is assumed that the maximum slope is achieved before wheel slip occurs.

If the ratio is changed to 5:2, the low speed characteristics are reduced

with a lesser effect on the higher speed: the speed will increase (if friction can be overcome), but the effect of slopes and bumps will be to slow the

vehicle more noticeable than with the lower gearing. If there is too much friction the vehicle won’t be able to accelerate to the maximum speed

because it won’t get past the initial torque drop-off: frictional losses increase as the square of the rotational speed – all the more reason to

keep them small.

JollyStolly

Page 86 of 155



0

20

40

60

80

100

120

140

160

0 0.2 0.4 0.6 0.8 1 1.2

Speed, mph


5:2 Ratio

5:1 Ratio

Wheel slip (60kg mass, m = 1.2)

Figure 32: Pulling Force vs Speed for Different Ratios

If friction is really bad, the more highly geared system may end up being slower than the lower geared system…


0

20

40

60

80

100

120

140

160

0 0.2 0.4 0.6 0.8 1 1.2

Speed, mph


5:1 Ratio

5:2 Ratio

Drag

Wheel slip (60kg mass, µ = 1.2)

Figure 33: System with poor drag.

JollyStolly

Page 87 of 155


APPENDIX E: Weight, Balance & Performance.

JollyStolly

Page 88 of 155


E.1 Introduction.

E.2 Weight & Balance.

With no driver or passenger the total weight is 52 kg. The distribution is as shown below.

Figure 34: CG position, EMPTY

The longitudinal centre of gravity is 40% of the distance between the rear

and front axles.

20 kg 32 kg

JollyStolly

Page 89 of 155


With a 30kg driver, this loading becomes:

Figure 35: CG position, DRIVER only.

The longitudinal centre-of-gravity is 61.7% of the distance between the

rear and front axles.

50 kg

31 kg

JollyStolly

Page 90 of 155


E.3 Performance.

E3.1. Duration Duration is a function of the loading placed on the motors (slopes, weight

of passengers, etc) and the battery capacity. It is also affected by the use of the lights, horn, etc. Boredom seems to kick in before the battery is

noticeably flat.

Using a 26Ah Gel battery gives approximately one hour’s (gentle) running time.

E3.2 Power.

Not directly measured as yet.

‘Exhibit A’ would be the rotary clothes-line that was flattened by an impish

five year-old….

‘Exhibit B’ would be the towing of two adults on kiddie-tractors over grass… (Exhibit B can’t be used in evidence – psychiatric reports have been

ordered into the adults involved).

‘Exhibit C’ would be climbing two car ramps…

JollyStolly

Page 91 of 155

Rev B

© Hugh Neve 2006

Charging….

Up….

Up….

“I think its stuck…Need 6WD”

Testing arrival-angle….

“Phew!”

JollyStolly

Page 92 of 155


E4 Stability.

E4.1 Lateral Stability.

This picture shows the unladen prototype JollyStolly at the angle at which

it is just starting to tip. (The wooden prop is there merely to allow me to run round and take the picture)

Figure 36: Illustration of lateral tip angle.

This angle is just over 45 degrees. THIS WILL BE REDUCED BY THE

PRESENCE OF DRIVER/PASSENGERS and any asymmetry in the loading.

Assuming that the CG is on the midline of the vehicle, the vertical position of the CG can be estimated to be as shown above – about 50% of the

height of the hull.

JollyStolly

Page 93 of 155


E4.2 Longitudinal.

From the above, it is reasonable to assume that the CG (for the empty

vehicle is:

• 40% of the distance between the rear and front axles;

• Approximately 50% of the height of the hull.

This places the CG at the position shown in the picture below.

Figure 37: Position of CG.

The angle shown is approximately 75 degrees, so it is very unlikely to tip-up during normal use – unless the CG shifts significantly due to heavy

passengers, etc., and is likely to be limited by the angle of the rear section of the hull.

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APPENDIX F: Wiper-motor mounting.

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This Appendix discusses the installation of automotive wiper-motors in the

plywood structure of the JollyStolly.

G1. Background. Wiper-motors come in all sorts of shapes and sizes, but invariably have a

central driven shaft and three threaded mounting holes on a fixed pitch about this shaft. The pitch and angular positioning of these holes varies

with manufacturer and the model of donor vehicle, hence this guide being quite generic.

G2. Forces/Moments Involved.

When driving a chain the following forces/moments are exerted by the wiper-motor: these are the forces that must be resisted by the mountings.

Figure 38: Forces on Motor

G3. Mounting Schemes.

The following possible schemes can be used or adapted to install the motors (the chosen application will depend upon the configuration of the

mounting holes / motor):

a) Basic angle bracket:

A simple piece of angle can be used to effect a motor mount. Holes can be drilled on one limb to mate with the mounting holes of the wiper motor,

and on the other limb to allow bolts to be used to secure to the hull, etc.,

as required.

The latter mounting holes should ideally be oval in shape to allow the motor to be adjusted so as to take up tension in the chain.

Direction of rotation

Reaction

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Figure 39: Simple mounting bracket.

Figure 40: Oval holes allow for movement.

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b) Complex bracket:

The more desirable bracket emulates the installation in the donor vehicle

and is more secure and resistant to deflection. A face-plate is manufactured that allows the driven section to pass through and the

original fixings to be used. this is attached to a flat plate using pop-rivets and strengthened further with pieces of flat plate/angle as required.

Figure 41: More complex bracket.

Once installed the tendencies of brackets to deflect will become apparent

and can be counteracted through the installation of struts, braces, etc.,

It goes without saying that the structures to which the brackets are

attached have to be sturdy: any local deflections can be counteracted by

the use of battens, angles, doublers, etc.,

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APPENDIX G: Parental Override.

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This Appendix details the implementation of a radio/control “parental

override” function to enable a responsible adult to interrupt or countermand the commands being made from the cab.

G1. Background.

It is possible that the driver of the JollyStolly:

a) Has not driven a powered vehicle before; b) Is upset with something/someone;

c) Is desperate not to relinquish ‘their turn’; d) Is overtired;

As such it might be a good idea to be able to interrupt the command

signals or override them remotely. The latter allows the owner of the remote controls to have a very large radio-controlled vehicle, which can be

fun in its own right…

G2. Methods.

All of the methods and means detailed herewith use radio-control equipment, the servos operating microswitches that either break or short

parts of the command circuitry: if variable voltages are being used in the control of steering or speed it is conceivable that the servos could also vary

the voltage via potentiometers etc.,

Note that it is necessary to match the throw of the servo to the operational range of the microswitches to avoid loading the servos permanently as

they hold a given position: this can be achieved via programmable systems or by careful arrangement of servo and switch.

G2.1. Kill-switch

The simplest form of override is to place a microswitch in the supply circuit

to the control system – when the servo activates the microswitch the circuit is broken and the vehicle stops (this option can also be implemented

via a lanyard if radio control gear is not available).

G2.2 Ownership. The above technique can be extended to use the microswitch to switch

between the ‘normal’ commands from the cab to the ‘override’ commands supplied via additional servo/microswitches.

In the prototype the servos and microswitches were mounted in a ‘module’

that could be removed at will, with the electrical connections being made via a 9-pin DIN plug/socket.

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Figure 42: Detail of parental override module.

Forward / stop

Left Right

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APPENDIX H: Things I didn't get round to

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Page 102 of 155


I didn’t get round to doing anything more than thinking about these ideas:

1) I did consider the use of small chain-driven jockey-wheels to transmit

torque to the middle pair of wheels. Positioned under the loadbed they might not be too obvious and could be arranged so as to cope

with the movement of the wheels during steering;

2) Wing-mirrors would be a good addition - as would a few other ‘scale’ additions;

3) My garage contains a prototype winch: electrical driven (another

wiper-motor!) and feeding cord through 10mm steel tube to an outlet at the front of the hull. It languishes in the garage because I could

not decide how to make such a device completely safe;

4) The prototype has the un-intrusive whine of a milkfloat, not the roar

of a straight-eight: some form of sound-generation would be a bonus (let me know if you have any luck);

Figure 43: This sound module came from a toy tractor.

5) I’m told the seat could do with a cushion, and, by one user at least, some curtains!

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APPENDIX I: ‘Atlas’ Crane.

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I.1 Introduction.

The MKII Alvis Stalwart FV623 was an adaptation of the FV622, modifications including the fitment of an Atlas Crane to fulfil an artillery

limber role. The crane was able to slew from side to side, to lift heavy loads with the job folded and lift lighter loads at a distance of up to 4.05 m. This

was always on the ‘wish-list’ for the JollyStolly and, having now been added, is detailed in this Appendix. There was no design-aim to allow the

lifting of heavy loads, or for the lifting of humans or delicate items!

I.2. Design Breakdown.

The design is broken down and described in sections, detailing how they

are constructed and designed and how they are integrated.

Figure 44: Components of Prototype Crane

Boom

Column

Boom centre

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Figure 45: Components of Original Crane.

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I2.1 Column.

The column supports the boom and allows the boom to be lifted (“dericking”) and for the boom to slew. The column supports the electrical

and fluid connections to the other components.

The column is of glued-and-screwed plywood construction mounted on a platen of circular plywood that allows the column to slew. The platen has

an access hole that allows for electrical and other connections to be made. Both sides of the column are manufactured at the same time, whilst

screwed together, to ensure maximum accuracy.

The column allows other components (i.e., the boom and the boom-lifting mechanism) to pivot: to facilitate this short lengths of steel tube are

epoxied into the plywood – ensuring that they are kept co-axial whilst the epoxy cures. Note that small diameter steel tube can often be neatly cut

using a pipe-cutting tool designed for domestic plumbing.

I2.2 Boom

The boom pivots up and down (derricking) on the column and performs the lifting capability.

The boom is manufactured from glued-and-screwed plywood, with steel

tube epoxied into accurately drilled holes where required. A central rib of 18mm plywood facilitates the connection of the boom-lifting mechanism.

I2.3 Boom Lifting Mechanism

The boom is lifted through the action of ‘Linak’ linear actuator from a motorised arm-chair. This was bought from eBay and is operating at half of

its 24V rating.

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I3. 1 Construction

The components of the column and column-base are cut out from 12mm plywood. Before they are assembled the motor, the actuator and the

boom-centre have to be laid out against a column-side to ensure that the following criteria are met:

• The actuator mount is as low as possible whilst allowing the motor to pivot;

• The actuator is mounted on the mount so as to be as far ‘aft’ as possible.

• The actuator is mounted so that it can reach both fully-extened and fully-retracted conditions unimpeded by the movement of the boom

Figure 46: Section View of Crane Column

When the boom is at its lowest position the angle between the column base

and the axis of the wiper-motor output shaft (Angle φ) must be less than

90 Deg, otherwise the boom will not lift.

Pivot of boom lifting

mechanism

Angle φ

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Page 108 of 155


The components of the crane can now be glued and screwed together and

the various holes fitted with the short lengths of steel tube – ensuring that they are kept aligned as the epoxy cures.

A short length of steel or aluminium angle has to be screwed to the motor

mount and drilled to match the pivot holes in the column-sides.

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Page 109 of 155


Figure 47: Actuator Mount

The crane platen can be assembled and the crane column secured to it by fixing the lower circular plate. Note that this is best achieved after

JollyStolly

Page 110 of 155


painting, to ensure a smooth surface and to prevent water ingress that

might swell the plywood.

I4.1 Control

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I5.1 Performance

As an indication, the prototype crane is capable of lifting the 6kg kiddie-tractor shown in the Figure from the floor to the sort of height shown. The

boom is at its minimum length: extending the reach reduces the lifting capacity accordingly.

With the 6kg load there is no apparent tendency to tip-over at all.

Figure 48: Crane Capability

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I5.1 More.

During development of the prototype a powered jib was attempted using medical syringes

as hydraulic pump (vehicle end) and hydraulic actuator (jib end) to extend the jib.

Unfortunately, the elasticity of the pvc hose and relatively loose tolerances of the linkages

meant that there was a lot of backlash in the system, with the jib deflecting under load to

the extent that it couldn’t really lift anything.

Nice smooth movement though…

JollyStolly

Page 113 of 155


APPENDIX J: Kitchen Pass

JollyStolly

Page 114 of 155


KITCHEN PASS

I, ………………………… (‘The Applicant’) hereby formally request permission from

……………………………. (‘The Authority’) to build a JollyStolly. The approval of this pass by The

Authority under the powers invested in Him/Her* infers an understanding that this will

involve time alone in the shed / garage / workshop*. The Authority understands that this

will mean that The Authority shall know where the applicant is at all times, and that the

aforementioned applicant is not down the pub and/or with other women/men*.

The Applicant undertakes to attempt to comply with the following conditions where

possible: (The Authority to delete as applicable)

Not to bring sawdust / dirt into the house;

Not to work in his/her* best clothes;

Not to use kitchen utensils for workshop tasks;

Not to use the household vacuum cleaner in the workshop;

Not to stink the house out with thinners / white-spirit / paint*;

To try to limit time spent in the shed / garage / workshop*

In turn, The Authority hereby undertakes to attempt to comply with the following:

Not to stand silently watching and/or sucking air through his/her* teeth;

Not to go ‘all moody’ on The Applicant;

Not to attempt to obtain fiscal, material or emotional advantage

through emotional blackmail, to whit ‘moaning about time spent

in the shed / garage / workshop*’;

Not to keep mentioning for the next ten years things that might

happen to go wrong during construction;

To supply tea / coffee and biscuits (of a type to be agreed between The Applicant

and The Authority) on a regular basis;

Signed

…………………………… …../…../…… ……………………… …../……/…..

The Applicant The Authority

*delete as applicable.

JollyStolly

NUMBER

DWG 000 ISSUE A

TITLE

FORWARD BULKHEAD

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.

• Manufacture

from

9mm W

BP ply.

JollyStolly

NUMBER

DWG 001 ISSUE A

TITLE

MID BULKHEAD

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.

• Manufacture from

9mm W

BP ply.

Steering torque tube

passes through here

Modify as required

JollyStolly

NUMBER

DWG 002 ISSUE A

TITLE

AFT BULKHEAD

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

Included for

ventilation. Include

as required

Steering torque tube

passes through here

Modify as required

JollyStolly

NUMBER

DWG 003 ISSUE A

TITLE

HULL SIDE

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Does not show pilot

holes for screws.

Factory-prepared edge if

possible.

JollyStolly

…..

NUMBER

DWG 004 ISSUE A

TITLE

HULL BASE

DRAWN

HWN

© Hugh Neve 2006

Factory-prepared edge if

possible.

• 1 Off required.


9mm W

BP ply.


holes for screws.

130

340

230

390

FWD AXLE C/L

MID B/HEAD

MID AXLE C/L

AFT AXLE C/L

AFT B/HEAD

FWD B/HEAD

521

JollyStolly

NUMBER

DWG 005 ISSUE A

TITLE

HULL FWD PANELS

DRAWN

HWN

SHEET1

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Cut over-size as

trim

ming will be

required.


holes for screws.

JollyStolly

NUMBER

DWG 005 ISSUE A

TITLE

HULL FWD PANELS

DRAWN

HWN

SHEET 2

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.


trim

ming will be

required.


holes for screws.

JollyStolly

NUMBER

DWG 005 ISSUE A

TITLE

HULL AFT PANEL

DRAWN

HWN

SHEET 1

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.


trim

ming will be

required.


holes for screws.

JollyStolly

NUMBER

DWG 007 ISSUE A

TITLE

LOADBED

DRAWN

HWN

SHEET 1

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Position and size of

access panels m

ust

be decided according

to installation of

components.

• Total length

shouldn’t exceed

40% of total length:

less if possible.

JollyStolly

NUMBER

DWG 007 ISSUE A

TITLE

LOADBED

DRAWN

HWN

SHEET2

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Position and size of

access panels m

ust

be decided according

to installation of

components.

• These holes 20mm

smaller on each edge

that those on

previous sheet.

JollyStolly

NUMBER

DWG 007 ISSUE A

TITLE

LOADBED

DRAWN

HWN

SHEET 3

© Hugh Neve 2006

• 2 Off required.


9mm W

BP ply.

JollyStolly

NUMBER

DWG 007 ISSUE A

TITLE

LOADBED

DRAWN

HWN

SHEET 4

© Hugh Neve 2006

JollyStolly

NUMBER

DWG 007 ISSUE A

TITLE

LOADBED

DRAWN

HWN

SHEET 5

© Hugh Neve 2006

Forward panel

Side panel

Batten framework

Battens used to

build up rear

boxing.

Panel removed for

clarity)

JollyStolly

NUMBER

DWG 008 ISSUE A

TITLE

CAB AFT PANEL

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

JollyStolly

NUMBER

DWG 009 ISSUE A

TITLE

CAB FWD PNL & BEAD

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Mark rivet holes (not

shown) 10mm from

edge of windows

• MKII Vehicle shown.

JollyStolly

NUMBER

DWG 010 ISSUE A

TITLE

CAB SIDES

DRAWN

HWN

© Hugh Neve 2006

• 2 Off required.


9mm W

BP ply.

• MK II Vehicle shown

JollyStolly

NUMBER

DWG 011 ISSUE A

TITLE

CAB TOP

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

JollyStolly

NUMBER

DWG 012 ISSUE A

TITLE

CAB BASE 1

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


9mm W

BP ply.

• Modify as per specific

design.

JollyStolly

NUMBER

DWG 012A ISSUE A

TITLE

CAB BEAD SHT2

DRAWN

HWN

© Hugh Neve 2006

• 1 Off required.


planed tim

ber, 20 x

20 approx

• Modify as per specific

design.

• The angle does not

have to be achieved

to the stated level of

precision!

JollyStolly

NUMBER

DWG 013 ISSUE A

TITLE

STUB AXLES

DRAWN

HWN

© Hugh Neve 2006

• 4 Off required.


mild steel.

• Modify to suit

wheels/design.

Weld

Weld

Optional

JollyStolly

NUMBER

DWG 014 ISSUE A

TITLE

AXLE BEAMS

DRAWN

HWN

© Hugh Neve 2006

• 2 Off required.


mild steel.

• Modify to suit own

design.

Weld top

& bottom

each

side.

To suit

pedestal

bearings

being

used.

JollyStolly

NUMBER

DWG 016 ISSUE A

TITLE

REAR AXLES

DRAWN

HWN

© Hugh Neve 2006

• 2 Off required.


mild steel.


design.

Angle to suit

hull-sides.

Refer to

DWG001 or

measure.

Contains

grub

screw.

JollyStolly

NUMBER

DWG 018 ISSUE A

TITLE

DRIVESHAFTS

DRAWN

HWN

© Hugh Neve 2006

• 2 Off required.


mild steel.


design.

• Requires lathe

access

• Do not paint.

Design to

suit

sprocket

fixing

method

Weld &

grind.

Design

to suit

wheels.

JollyStolly

NUMBER

DWG 019 ISSUE A

TITLE

CAB SIDES

DRAWN

HWN

© Hugh Neve 2006

Fixed

to

18mm

WBP Ply pad fixed

to underneath of

hull.

Woodruff

key /

weld(!?)

IGUS

bearing

JollyStolly

NUMBER

DWG 020 ISSUE A

TITLE

PEDESTAL BEARING

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

NUMBER

DWG 021 ISSUE A

TITLE

IGUS BEARING

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

NUMBER

DWG 022 ISSUE A

TITLE

BEARING – T/M

ISSION

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

• 4 Off required.


softwood or

hardwood

(preferable).

(This

angle

is

the

same as the angle of

the bulkheads)

NUMBER

DWG 023 ISSUE A

TITLE

BEARING

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

40 m

m

42 m

m

12 m

m

7 m

m

• Not to Scale

• To be m

odified to suit any m

odification

of the profile of DWG014, elongated by

5% vertically.

NUMBER

DWG 024 ISSUE A

TITLE

BEARING

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

Resize fuses as necessary based on current drawn (Wattage divided by voltage)

NUMBER

DWG 025 ISSUE A

TITLE

MAIN W

IRING

DRAWN

HWN

© Hugh Neve 2006

Controller;

Horn;

Lights;

RL1

RL1

Steering

Drive

Keyswitch

Master

switch

+12V

10A

40A

40A

JollyStolly

• 9mm W

BP Ply

• Assumes 35mm battens & 9mm ply used in loadbed ‘boxing’ (DWG 007)

• Assumes 22mm battens are being used.

• Measure gap before cutting, re-sizing if necessary.

• Fit with corrugated plastic.

• If possible cut out recess after construction using a router (a bit with a bearing fitted)

NUMBER

DWG 026 ISSUE A

TITLE

TAILGATE

DRAWN

HWN

© Hugh Neve 2006

JollyStolly

Its weatherproof lair… The corrugated sheet is pop-riveted to a sheet of

18mm ply, and the tailgate is open to let water run off the tarp and out the back…

10mm holes are also drilled at the far corners of the loadbed – just in case!

JollyStolly

Bit more detail of tailgate, hinges, etc…

JollyStolly

Main human-machine interface. Ex Commodore Amiga…

JollyStolly

Keyswitch, light switch and horn button.

JollyStolly

Do as I say, not as I do…

It shows the scars of a thousand modifications, revisions and re-wires, but

hey – that’s what prototypes are for!

JollyStolly

A jubilee clip can be just as effective as a split-pin, doesn’t have so many

sharp edges, it can be re-used and only needs a screwdriver.

JollyStolly

Polycarbonate sheet, sprayed matt black on the inside makes a great

alternative to plywood for glazing the windows.

JollyStolly

Personal Role Radio fitted to provide two-way communications. This is

wired in to the vehicle supply.

JollyStolly

Rear

Front

Rear lights are LED clusters used for advertising, etc.,. Front lights are 3

white LEDs fitted into the front of a torch bought from eBay for 99p. (One each side)

JollyStolly

“Version 2” tailgate (DWG026) with recessed corrugations.

Documents

Jollystolly - Alvis Stalwart