BHT: Jun 2010

BULK HANDLING TODAY June 2010 1

2 BULK HANDLING TODAY June 2010

BULK HANDLING TODAY June 2010 �

June 2010

ContentsCover Story5 Understanding is Key

Chutes and Liners9 Dead Box Erosion

Plant Hire11 Down to Earth Goodness15 Reaching New Heights

Power Transmission19 To Vary Speed, or Not...?27 Fluid Power

Haulage Technology31 To a New Level

33 Market Forum

Endorsing BodiesCMA (Conveyor Manufacturers Association)

HCASA (Hydraulic Conveying Association of SA)

LEEASA (Lifting Equipment Engineering Association of South Africa)

RFA (Road Freight Association)

SAIMechE (SA Institution of Mechanical Engineering)

SAIMH (SA Institute of Materials Handling)

•

•

•

•

•

•

Proprietor and Publisher:PROMECH PUBLISHINGTel: (011) 781-1401Fax: (011) 781-1403E-mail:[email protected] Website: www.promech.co.zaManaging Editor: Susan CustersJoint Editor: Andrew Lanham

Advertising Sales: Surita MarxDTP: Zinobia Docrat and Sanette Lehanie

Printed by:Typo Colour PrintingTel: (011) 402-3468

Our e-mail address is [email protected]

Visit our website on www.promech.co.za

The monthly circulation is 4 016

CopyrightAll rights reserved. No editorial matter published in “Bulk Han-dling Today” may be reproduced in any form or language without written permission of the publish-ers. While every effort is made to ensure accurate reproduction, the editor, authors, publishers and their employees or agents shall not be responsible or in any way liable for any errors, omissions or inaccuracies in the publication, whether arising from negligence or otherwise or for any consequences arising there-from. The inclusion or exclusion of any product does not mean that the publisher or editorial board advocates or rejects its use either generally or in any particular field or fields.

Featured on the cover:

Roymec Materials Handling Tel: (011) 804 5123Email:[email protected]

� BULK HANDLING TODAY June 2010

CONVEYOR MANUFACTURERS ASSOCIATION

From the Chairman’s Desk

Simon Curry

All members subscribe to the CMA Code of EthicsABB IndustryAfripp ProjectsActomAtlanta Manufacturing Bateman Engineered TechnologiesBauer a Division of Hudaco TransmissionBMG (Bearing Man Group)Bearings InternationalBelt Reco RSA Bonfiglioli Power Transmissions Bosworth A Division of Hudaco Trading Brelko Conveyor ProductsCKIT Conveyor Engineers Continental Crushing & Conveying

CMA Members List as at May 2010

Conveyor WatchCMG Electric Motors SACPI TechnologiesCPM EngineeringCT SystemsDavid Brown Gear Industries Delras EngineeringDRA Mineral ProjectsDunlop Belting ProductsDymot Engineering Company ELB Engineering ServicesFacet EngineeringFenner Conveyor Belting SAFlexible Steel Lacing SAHansen Transmissions SA

Hosch - FördertechnikM & J Engineering Martin EngineeringMelco Conveyor Equipment Moret MiningMS Conveyor Pulleys SANepean ConveyorsOE BearingsOsborn Engineered Products SARead Swatman & VoigtRema Tip Top SARenold CroftsRoymecRSV ENCO ConsultingSandvik Materials Handling SA Schaeffler South Africa

Secrivest SENETSET AgenciesSEW EurodriveShaft EngineeringShaw Almex AfricaSiemens Southern AfricaSKF SATechnique Avant GardeThyssenKrupp Materials HandlingTransmission ComponentsTransvaal Rubber CompanyUnitek EngineersVeyance Technologies AfricaVoith Turbo Zest Electric Motors

W ith a slight deviation from the pattern of the last couple of years, it is again my pleasure to announce that not one but two award certificates were presented

at the Dinner. Highly deserving of the recognition that is recorded in the award certificate is Dave Pitcher, whose lifelong dedication to promoting the excellence of belt conveying is widely known in the industry. The second award, for assisting in promoting the excellence of belt conveying, was made to our long-serving Secretary, Chris Townsend.

Well done to both of you and may we enjoy many more years of your involvement in the belt conveying in-dustry.

Among the hon-oured guests at the Dinner, I was very pleased to welcome an ex chairman of the CMA, Brian Bell and his wife Pat. In fact, all past Chairmen were there going back to 1993 with Brian

This month it gives me great pleasure to tell you of the latest CMA highlight – the Annual Dinner. We moved to a larger venue for this year’s event and were rewarded with a bumper turnout of 290 members and their guests. All reports confirm that Abbott and Crabb were really appreciated without exception by everyone. I’m sure many of us haven’t had such a great laugh in simply ages and it was just fantastic to see all 290 people having such a good time! Thanks must also go to the Benoni Country Club, who made a great effort to ensure that the evening was a success, as well as to all the member companies who sup-

ported the event.

Bell, Alan Exton and Max Schenck, who was succeeded in 2003 by yours truly!

ErrataAn error in the worked example at the end of the specification CMA MC01 Rev00 of 2004 “Clamps for Belt Conveyors” has been identi-fied. This has now been corrected and Rev01 issued, which is avail-able as a download from the CMA website www.cmasa.co.za. The error in the example was in the incorrect calculation of force as 80% of the rated belt tension; the formulae in the specification itself are correct.

And lastly, I would like to remind you that the IMHC committee has called for papers for Beltcon 16, to be held on 3 and 4 August, 2011. If you are interested in presenting a paper, or would like a paper on a specific topic, please notify the IMHC Organising Secretary at [email protected].

Simon CurryCMA Chairman

Chris Townsend and Dave Pitcher


First you understand the material fully, then you design everything to facilitate flow. The

traditional approach of concentrating on structural or mechanical design constraints, has been turned on its head by Roymec. The company holds by the maxim that flow comes first. Understanding the nature and proper-

ties of the material being worked with is key. Only then does Roymec proceed to an opti-

mised, flow-driven design.

Rudi Pieterse, Divisional Manager Marketing & Proposals of Roymec, tells “Bulk Handling Today” that having their own in-house plant erection capability means that they not only

control all aspects of the design but the construction as well. “In this way, we are ‘masters of our own destiny’ and can ensure stringent quality criteria and delivery deadlines are met at all points along the value chain.”

Roymec’s national and international clients can attest to an impressive array of engineering and materials handling projects that have been success-fully delivered to date. Rudi adds, “We have grown significantly since Roymec’s inception in 1979. Our core business is the delivery of innovative, op-timised and reliable materials handling solutions to the mining and industrial markets. We prefer to do this on a lump sum turnkey basis as Every aspect of project execution is performed and project-man-aged in-house.

COVER STORY

Understanding Is Key

Impressive array of engineering and materials handling projects


COVER STORY

Zibulo Overland Conveyor that was commissioned in November last year,” says Rudi proudly.

Coal from Anglo Coal’s Zibulo Colliery is processed at the Phola Processing Plant, an Anglo Coal, BHP Billiton joint venture operation. The colliery is connected to the Processing Plant by means of an 1 750 tph overland conveyor. At Zibulo Colliery, coal is brought to surface with incline conveyor

CV001 and discharged into a 6000t buffer silo. From the buffer silo, coal is fed into a crushing and screening circuit with a second conveyor CV002.

Longest in AfricaThe material is then accelerated to a predetermined speed with acceleration conveyor CV003 and transferred to the Zibulo overland conveyor CV004. This configuration allows the overland conveyor to operate at optimal efficiency in conveying coal to the Phola processing plant almost 16kms away.

This conveyor is the longest single flight overland conveyor in Africa. It is one of the longest single

Variety of disciplines“Our nine professional engineers look after a variety of disciplines, which enables us to take on sizable and challenging materials handling projects. Adding to Roymec’s already impressive reference list, is the

This conveyor is the longest single flight overland conveyor in Africa


COVER STORY

flight overland conveyors in the world and features three horizontal curves and several convex and concave vertical curves. The high vertical lift (176m) of CV001 combined with the very long length of 15.9km for CV004 necessitated comprehensive static and dynamic analysis of the entire system. The suc-cessful commissioning of this landmark conveyor followed the completion of the materials handling system at Phola, also ex-ecuted by Roymec.

Customers come firstRudi says, “So far, we have met or exceeded customer expectations which probably accounts for the fact that we have a lot of repeat business from custom-ers. As they say, the best publicity undoubtedly is ‘word of mouth’.

This has led to Roymec establishing a new Material Handling Services Division. Rudi elaborates, “Here we provide our customers with comprehensive post-commissioning material handling services and product support such as the outsourced operation and maintenance of materials handling systems. We also offer materials handling with mobile plant with a specific focus on waste material such as discard and product stockpiles as well as the management and operation of tailings systems.

Ahead of the pack“While building on and establishing our core busi-ness, we also have to keep reinventing ourselves to remain one step ahead of the pack. That is why we have adopted a new logo signifying a renewed focus on our core business, while simultaneously expanding into new and exciting areas of opportu-nity, never forgetting to ensure that our customers come first,” says Rudi in conclusion.

Rudi Pieterse, Divisional Manager Marketing & Proposals, Roymec Materials Handling. Tel (011) 804 5123, Cell: 082 388 2843. Email: [email protected]

As they say, the best publicity undoubtedly is ‘word of mouth’


RFA Convention 2010

RFA Convention 2010

Wild Coast Sun

WITHOUT TRUCKS, SOUTH AFRICA STOPS!

Sunday 22 August to Tuesday 24 August 2010Shift into Overdrive


U retech managing director George Hoffmann says, “Overall material and maintenance costs have risen due to resource increases and mon-

etary fluctuations. With polyurethane products that are more economical than steel-based lining solutions, our customers have seen the benefit of implementing our products - not only to ensure equipment longevity, but to actually refurbish a piece of equipment in the shortest possible time.”

In 2008, Uretech introduced dead box lin-

Dead Box ErosionPolyurethane sheets and liners offer an inventive solution to mining and industrial applications where abrasive

materials and volumes cause extensive wear and product loss, costing companies in both equipment replacement and downtime.

ers to the mining market, the first of their kind. This enabled the liner to be installed in a chute already in use. Until then, the only alternative was replacing the entire application with a customised steel structure.

Low downtimeGeorge explains that the design of the dead box liner allows for intense material-on-material wear, with a compartment structure that causes the material to flow in an application without wearing out the liner - ideal for extremely heavy flow mining, such as the iron ore industry.

“Being lightweight, our dead box liner is easy to install, extremely cost effective, and allows for high wear liners to be replaced with low downtime.”

CHUTES AND LINERSRFA Convention 2010

RFA Convention 2010

Wild Coast Sun

WITHOUT TRUCKS, SOUTH AFRICA STOPS!

Sunday 22 August to Tuesday 24 August 2010Shift into Overdrive

This enabled the liner to be installed in a chute already in use


The compartment structure of the dead box

liner creates material on material flow and; therefore, there is little or no

wear on the liner or the structure itself, making it ideal for high volume areas.

For the taskAdds George, “The patented fibre-reinforced back-ing ensures that the liner is lighter than traditional wear liners, while still being sturdy enough for the task. Easy installation means less time taken for the replacement, which translates to further cost savings.”

CHUTES AND LINERS

In tests conducted at various plants, many ap-plications show polyurethanes outperform

rubber, plastics and even metals. “As a sacrificial surface, dead box liners should be easily removable, which is an area that

Uretech has focused on. We can remove damaged liners and replace them with fully

customisable fibre-backed polyurethane liners with little interruption to productivity.”

Valid solutionsFlexible and durable, polyurethane formulations are possible in a wide range of resilience. For high shock-absorbing uses, polyurethane can be made with rebound values of 10% - 25%. For applications requiring quick recovery, or where high-frequency vibrations are a factor, they can be made with rebound values from 40% - 70%.

Having built a reputation for providing cost-effective and valid solutions across a variety of applications, Uretech’s client base has grown to include many of the large mines and industrial companies. By continuing to seek innovative solutions for protec-tion, abrasion and even corrosion of equipment, the company is part of its client’s solutions in cutting down on day-to-day costs.

George Hoffman, Uretech, Tel: (011) 268-8860, Fax: (011) 447-2212, Website: www.uretech.co.za

As a sacrificial surface, dead box liners should be easily removable


PLANT HIRE

R ichard is a director of a family business, Bila Civil Contractors. His brother, wife and sisters all actively participate in running the various business units such as the plant

hire section under the wing of the main company based at Ivory Park near Midrand.

That he’s a down-to-earth man shows immediately as he starts pointing out the features of the brand new equipment they’re busy testing. “We’re also checking out a new operator,” he says with a warm smile. “You can see he’s a professional, handling the machine swiftly and precisely, yet gently and with great care.”

EquipmentThis turns out to be at the core of Bila’s success in hiring out bulk earthmoving equipment over the last six years. Certified professional operators deliver the optimum, cost effective operational time on a machine that’s being billed by the hour. “Four new excavators add to our pool of front-end load-ers, graders, TLBs and a fleet of trucks so that we can offer the full complement of rental equipment needed for bulk earthmoving,” Richard says. “Our philosophy is to buy new equipment, so that we never let the client down.

“Experience has taught us that you can’t wait until the demand is high before investing in new

equipment. You have to have machines readily available all the time because people don’t like to wait around while you run around sourcing equipment,’ he adds. “Having our workshop is also a great help in ensuring that all equipment is serviced and ready to go out at a moment’s notice. The machinery goes out to all the other provinces, which are some distance from us, so we have to ensure that it arrives on site to start working im-mediately without any hitches.”

To pin Richard Bila down for an interview proved to be very challenging, but when “Bulk Handling Today” eventually meets him we understand why. It’s because he’s not behind a desk in his office talking to nosey journalists. In fact, we meet Richard on site. He’s not bothered by the dust covering his shoes as he gets behind the controls of a brand new excavator, the fourth

of a series of new excavators he’s just bought.

Down to Earth Goodness

Richard Bila of Bila Civil Contractors in one of his new excavators

Handling the machine swiftly and precisely, yet gently and with great care


ConstructionIn addition to the equipment rental business, Bila has the staff and infrastructure to handle construc-tion work on a project basis. The company’s track record shows work done for government departments and private entities in all provinces in South Africa. This includes work like embankment protection, storm water management systems, road surfacing and the building of schools, police stations, housing and commercial properties.

“We even have a stockyard where we keep all the basic building materials you might need for construction projects,” Richard adds.

RentalsFor the convenience of clients, Bila offers two rates for the hire of earthmoving machinery; a dry rate and a wet rate. “The dry rate, which most people opt for, does not include diesel and the client therefore provide his own fuel while we provides fuel at a flat rate when they hire at the wet rate charge,” says Richard. “The wet rate is really for those with a short-term requirement. It’s not unusual to hire out a machine just for a couple of hours, so we cater for these clients as well.”

MarginalisedThe ideal for any company is the long-term rental market and in this respect, Richard has some machines working on the Medupi power station project. “However, even though we continuously tender for project work and we certainly have the capability to do it well, we still feel we’re being marginalised,” he says.

The new addition to Bila’s pool of plant hire equipment

PLANT HIRE

BULK HANDLING TODAY June 2010 1�

ing companies, not only in plant hire, but also in civil construction.”

Richard Bila, Bila Civil Contractors, Tel: (011) 261-0241, Email: [email protected], Website: www.bila.co.za

The workshop where equipment is serviced and checked before it goes out

PLANT HIRE

A TLB form Bila at work

“Despite the fact that we’re an entirely black-owned company with 30% of the shares owned by females, this does not seem to count in our favour when it comes to projects,” Richard adds. We regularly get promises, but it never materialises and I simply don’t know why. Our prices are competitive and we have a good track record of not just finishing all our work on time, but often before time in some cases.”

The futureBut Richard’s spirit is not dampened and entrepreneurial flare is kept alight. “We’re always at the ready to take off at full speed, all we need is a chance to prove that we’re better than most,” he says in conclusion, smiling broadly. “So we’ll just keep on tendering, and because we’re a law-abiding company that plays by the book in terms of safety, financial management and providing opportunities for our people, we’re determined to grow into one of the lead-

We still feel we’re being marginalised

1� BULK HANDLING TODAY June 2010Our drive is your performance.

Hägglunds Drives South Africa (Pty) LtdP.O.Box 2851, 1610 Edenvale, JohannesburgPhone: + 27 (0)11 454 4933, Fax: +27 (0)11 454 5088E-mail: [email protected], www.hagglunds.com

Tough demands have met their match.

Let us know your demands.


“Steinmüller’s Plant Hire’s key differentia-tors are a personal interface with experts, customisation of solutions for client needs through detailed studies, well trained crane

operators and its superior safety record. In addi-tion, the company has a wide service offering of equipment for hire, which spans 24 000 items,” he says.

Marketing toolThe highly professional and personalised service,

Reaching New HeightsSteinmüller Plant and Equipment Hire, a division of Steinmüller Engineering Services, has built up a pool of

plant hire equipment ranging from electric drills to some of the largest cranes available in South Africa. “Bulk Handling Today” speaks to a representative of Steinmüller Plant Hire, Marcelino Da Costa, to hear more about

this highly competitive industry.

in conjunction with high quality and reliable equip-ment sets Steinmüller’s Plant Hire apart from other companies.

“I personally interface with our clients,” Marcelino says. “The responsibility in terms of on-time deliv-ery as well as the service and maintenance of our equipment lies with me directly, 24/7.”

After 25 years in the business, Marcelino has also learnt the merit of having good, reliable and communicative equipment operators for complex equipment such as cranes. “Our crane operators are recognised as key to customer satisfaction and retention, therefore we spend a lot of effort in training them properly,” he says.

“This effort certainly pays off with clients often requesting an operator by name, because the op-erator understands what he does and works within the set safety limits.”

The scopeThe 24 000 items for hire from the Plant Hire division comprise cranes, tractors, transformers, generators, welding plant, compressors, winches, trailers and hydraulic pumps and jacks, for use in the construction and plant maintenance industries.

Marcelino Da Costa, the representative of Steinmüller Plant Hire

Considering that it takes about 30 trucks to move a large crane and all its components to site, it’s crucial to pre-plan all possible operations

PLANT HIRE

Our drive is your performance.

Hägglunds Drives South Africa (Pty) LtdP.O.Box 2851, 1610 Edenvale, JohannesburgPhone: + 27 (0)11 454 4933, Fax: +27 (0)11 454 5088E-mail: [email protected], www.hagglunds.com

Tough demands have met their match.

Let us know your demands.

With clients often requesting an operator by name

1� BULK HANDLING TODAY June 2010

You have to consider the width of the outriggers, how big the crane is, how stable the ground is and if there are other structures in the vicinity which could interfere with crane movements

“Our crane and lifting equipment ranges from five tonne mobile hydraulic cranes to 500 tonne cranes, including lattice boom cranes and all sizes of mobile cranes in between,” says Marcelino. “Today we not only supply equipment for mechanical construc-tion and refurbishment to projects in the power gen-eration, petrochemical, and mining industry, but also to the general industrial sector,” he adds.

How it works“Our knowledge and ex-tensive experience in the erection of plant enables us to carry out detailed rigging studies to help the client in choosing the right equipment, but also to as-sist in solving challenging problems on site.”

A transaction starts off with just a few simple questions.

“In the case of cranes, for instance, we find out the weight as well as the height and radius required,” Marcelino explains.

“If it is a regular client, I sit down with them to personally work out his or her needs. If it’s a new client I prefer to go out to site because there are many other factors to take into consideration.

“You have to consider the width of the outriggers, how big the crane is, how stable the ground is and if there are other structures in the vicinity which could interfere with crane movements.”

LiftingOn his computer screen Marcelino demonstrates exactly what he means. “In this case, for example, a client wants to build an 8000 tonne bunker for coal storage in an established bulk materials han-dling operation,” he explains.

“I go out and study the ground conditions where the crane will work, check all the existing structures as well as the materials they want to lift. Then I draw up a graphic for the specific crane that will be able to handle everything they need to lift, to build the bunker.

“And we don’t charge for site visits,” adds Mar-celino.

He continues explaining: “In our experience it’s not always a case of people underestimating the size of the crane they need. I often find they can comfortably do with a smaller crane than the

PLANT HIRE


one they originally asked for. It’s not always about money, ours is a scientific approach to deliver a pro-fessional service to ensure the client always comes back to us.”

Pre-planConsidering that it takes about 30 trucks to move a large crane and all its components to site, it’s cru-cial to pre-plan all possible operations that the crane may be used for. “This is particularly important in the case of a static crane or one mounted on tracks,” adds Marcelino.

“We have a long term rig on a site at Secunda right now where we planned around the full extent of the project in anticipa-

PLANT HIRE

One of the cranes out the 24 000 items for hire from the Plant Hire division

Cranes are crucial to plant construction

Go to great lengths to keep our safety record untarnished

tion of all future lifts that may be required to get components into position. In addition, we constantly liaise with the client for the most suitable times to carry out maintenance and service on the equipment.

Safety“In conclusion, in plant hire, safety is crucial,” says Marcelino. “At Steinmüller we take safety very seriously. Our record is a great source of pride and we go to great lengths to keep our safety record untarnished. Lifting is a dangerous activity, so our operators will never take chances. They’ve been trained to operate within the specified limits and if anything is outside the scope of the equipment they operate, they stop immediately and phone me, so I can discuss the matter with the client.”

Marcelino Da Costa, Steinmül-ler Plant & Equipment Hire, Tel: 082 9044 568, Email: [email protected] . Visit www.steinmuller.co.za for more information.



POWER TRANSMISSION

“Bulk Handling Today” speaks to Stephan Obser, regional sales manager of Voith Turbo, about his findings garnered from experience in conveyor installations across the globe.

“There are many different drive solutions, but people tend to forget what happens further down the line when the speed of the belt constantly changes,” he says. “A common mistake is that they only focus on one section, varying the belt speed, while the rest of the system simply isn’t designed for higher speeds, resulting in increased wear and higher energy costs.”

Stephan compiled a paper from the studies he conducted worldwide. In this paper he concludes; “The general statement that speed regulation on belt conveyors results in energy savings, has clearly been disproved,” he says. “Arguments in favour of varying speed in order to prevent wear have been negated. Arguments in favour of wear prevention through variable speed have equally been negated.”

General observations on speed adaptation Adapting the belt speed serves the purpose of ensuring that the average material filling level on the belt is always at maximum capacity.

This measure is intended to reduce the frequency of

To Vary Speed, or Not...?For some time now variable speed has been the buzz word in the bulk conveying industry, but there seems to be a degree of misinterpretation of the actual consequence of summarily varying the speed of the belt without

considering the system as a whole, especially when upgrading an existing system. Studies worldwide have now revealed that the phenomenon of variable belt speed, haphazardly applied, results in excessive wear on

belts, gearboxes and bearings in conveyor systems.

the belt circulation around the drums. It has been erroneously assumed that such a measure would increase the service life of the belt connections and hence the entire belt. Stephan’s paper shows that this assumption is incorrect.

Influence of speed adaptation on belt drive components Stephan’s paper focused on the individual com-ponents of the belt conveyor and highlights their relevance on the belt speed.

Fig. 2 shows a simplified scheme of the belt con-veyor and its key components.

The belt conveyor consists primarily of the two

Fig. 1: a) Constant filling level due to adapting belt speed

Fig. 1: b) variable filling level due to constant belt speed

Stephan Obser


return drums (head and tail); long belt conveyors have, of course, further drums. For reasons of space, the drive is consequently not at the head of the system, but installed further back with further drums. In order to introduce higher torque, the wrap-around angle of the belt around the drum is increased.

The Eytelwein formula applies: , where μ represents the adhesive value between belt and drum, while α denotes the wrap-around angle.

The belt is supported by rolls, arranged at regular intervals across the entire length of the conveyor, either as garlands or staggered.

Material loading / Material release The design of the material release system depends on several factors. First of all, there are the flow characteristics of the material. Depending on the flow characteristics, the release station is designed either as a chute or a box, in order to prevent mate-rial from sticking to the surface or piling up. At the same time, the material should be released in the direction of the follow-on belt, ideally at the same

1. Material loading

2. Material drop

3. Head drum (drive drum)

4. Bend pulley/deflecting drum

5. End drum or guide drum (tensioning drum)

6. Loaded section of belt

7. Return section of belt

8. Support rolls for loaded section of belt

9. Support rolls for return section of belt

Fig. 2: Schematic drawing of belt conveyor

10. Feeding rolls

11. Inward bend

12. Outward bend

13. Chute

14. Belt cleaner (horizontal scraper)

15. Belt cleaner (v-scraper)

16. Drive unit

17. Tensioning weight

POWER TRANSMISSION


POWER TRANSMISSION

speed, in order to prevent the material from slipping on the belt and causing wear.

Special aspects, for example, variable moisture levels of the material must also be taken into account. Again, these must be considered in order to ensure a material release that is satisfactory in view of the existing conditions.

Other aspects to be taken into consideration are the specific weight and the grain size of the material, as well as the distribution of grain sizes. These characteristics de-termine the ensuing release parabola of the material: light, fine-grain material will end up more compact at the release drum than coarse, heavy material. The loading table must be designed accordingly.

It is therefore quite obvious that aspects like those mentioned above have a significant influence on the design of the release point. If the speed of the belt conveyor is to be variable, the release point must be adapted to these changing release parabolas, in

order to prevent the material from sticking or piling up – a challenge for any design engineer.

Idlers / PulleysWith conventional belt conveyor systems, idlers and pulleys are unlikely to wear out at the mantle, as long as the system has been aligned properly.

Fig. 3: Load cycle diagram

Fig. 4: Comparison of specific energy requirements at variable belt speed vs variable filling level.


In fact, the element limiting the service life of the idlers are actually the bearings.

The bearing life is calculated as: with C: load rating, P: equivalent load (in radial and axial direction) and p = 3 for grooved ball bearings.

With load collectives, the load equivalent arises from:

This illustrates that the service life of the bear-ings depends much more on the load (directly proportional) than on the speed (proportional to the third root).

The service life of the bearings is therefore nega-tively affected if the average filling level on the belt conveyor is kept high as a result of speed adaptation.

MaterialThe revised German standard DIN 22 101 takes the long-time rupture strength of the belt connec-tion into account. The long-time rupture strength represents the lifetime of the belt connection in dependence on pulling forces and the varying levels of load cycles. Load cycles are periods during which the belt is subjected to high stresses. An example is the moment when the belt runs around a drum, as the belt is compressed directly at the drum and

Fig. 6: Roll deformation resistance of various belt materials

stretched on its outer radius.

The load changes also take the straightening of the belt prior to release into account, as well as the length of the straightening (ie, the distance between a sagging and a re-straightened belt). Fig. 3 shows such a load diagram; stress is projected above the load cycle.

The diagram shows that the load cycle, ie, the number of cycles of a belt connection, rises with decreasing load. It is noticeable that a load reduc-tion of just 10% corresponds to almost a doubling of the stress cycles. In other words: a reduction of the load and/or the filling level leads to a longer service life of the belt connections. These findings suggest that speed adaptation would be disadvantageous.

POWER TRANSMISSION

It is noticeable that a load reduction of just 10% corresponds to almost a doubling of the stress cycles

Fig. 5: Resistance coefficient


POWER TRANSMISSION

Lauhoff, a publicly appointed sworn expert has carried out some research looking into the issue of energy sav-ings as a result of speed control. The specific energy, ie, the actual effort per metre of belt length and weight, allows a comparative statement.

The following two scenarios were calculated:1. Full filling level vs varying belt speed,2. Variable filling level vs constant belt speed,

Fig. 4 shows specific outputs for different belt speeds (blue) with dif-ferent filling levels (red). The specific energy requirement rises above the efficiency of the rated speed only for one speed. An adaptation of the belt speed towards lower figures is

definitely less favourable than varying the filing level at nominal speed.

Fig. 5 (ContiTech “Conveyor Belt Calculations”) confirms this trend. With decreasing material load, the resistance coefficient drops and reaches its minimum at 10% material load.

In this context it should also be considered how energy can be saved generally at the belt conveyor. Hintz at Hanover University, Germany, has carried out a study at various belts. The most important parameter is the roll deformation resistance, ie, the flexing resistance that the belt has to overcome at each support roll (Fig. 6).

Fig. 7 shows the forces at the belt in the sup-port roll area. At point A in front of the support roll, the belt is compressed, at point B the belt is compressed and finally at point C it is back to its normal elongation. UII is the roll deformation

Fig. 8: Percentage of individual resistances in the total resistance of a belt conveyor

U’: Idler resistance

U’’: Belt flexing resistances

U’’E: Roll deformation resistance

U’’G: Flexing resistance

U’’L: Material flexing resistance

Fig. 7: Forces between belt and support roll


resistance, ie, the effort to be made for the belt to overcome the support roll.

According to Lauhoff, the roll deformation resistance amounts to 61% of all resistances (see Fig. 8). This statement is based on a horizontally running belt conveyor without any additional lifting effort.

The roll deformation resistance depends largely on the belt pre-tension and the material load on the

Fig. 10: Frequency analysis of a transmission of the 1000 kW class

belt. The higher the belt pre-tension, the lower the roll deformation resistance. The higher the material load, the higher the roll deformation resistance

The belt pre-tension can be influenced only to a degree; on the one hand it is undesirable to have a slacking belt, on the other hand, tractive efforts should be as low as possible. What can be modified is the material load. Provided the belt speed remains unchanged while the material load (average filling level) varies, the roll deformation resistance will decrease in line with the lighter load.

According to Hintz it also appears advan-tageous to use rubber mixtures that are suitable for the ambient conditions and the material to be transported, in order to achieve genuine energy savings.

TransmissionsRWE Power AG in Germany reported

increasing numbers of transmission failures. B. van den Heuvel (RWE Power) carried out an analysis to find the cause of these breakdowns. At the end of the analysis were recordings of vibrations in the drive (Fig. 9).

It was established that transmission bearings and transmission shafts have different natural frequen-cies, which are not critical at short-time operation

Fig. 9: Vibration measurements in drives

POWER TRANSMISSION


POWER TRANSMISSION

(ie, during conventional start-up procedures), but become highly critical and cause damage to the transmissions during longer operation times (when they reach critical bending frequencies).

This investigation has been theoretically backed up with a frequency analysis (Fig. 10). It was found that there are certain speed ranges where the belt conveyor must not be operated, in order to prevent damage to the transmissions. In Fig. 10, the affected areas are shown in red. There is a narrow speed window between 400 and 500 1/min, another one between 650 and 900 1/min, as well as the nominal speed of 1,200 1/min.

Yet it must be pointed out that the affected speed ranges can be positively influenced by different ratios, different materials and different material strengths.

ControlIt has been shown that, during highly fluctuating loading and unloading situations, for example via a bucket wheel excavator, a down control of the belt speed is possible only to a certain degree, as the fluctuations might result in material overflow at the release points. It must also be borne in mind that speed control with associated monitoring of the filling level is highly labour-intensive. Increas-ing or decreasing the belt speed does not result in instant response, but requires a certain amount of time. In view of the situation at the release point outlined earlier, the control system must also be

able to adapt the transfer within this period, if necessary.

ConclusionThe statement that speed regulation at belt con-veyors would result in energy savings has been clearly disproved. The advantages that result from constant belt speeds and variable filling levels have been examined.

Arguments in favour of variable speeds in order to prevent wear have been negated. Arguments in favour of wear prevention through variable speeds have equally been negated. Problems that might occur as a result of belt speed control measures, have also been mentioned.

The conclusion is that operators should try to eliminate bottlenecks at the belt conveyor, so that it can always be operated with full material load and hence bring in maximum profit, instead of searching for solutions aimed at reduced belt speeds.

Stephan Obser, Voith Turbo, Tel: +49 7951 32 1986 (Ger-many), Email: [email protected] or Roy Webster at Tel: (011) 418-4036, Email: [email protected]

Arguments in favour of variable speeds in order to prevent wear have been negated



POWER TRANSMISSION

Over the past 50 years, Hägglunds Drives in Sweden has worked on the develop-ment of hydraulic drive technology to bring the world an alternative for high

torque applications, particularly the bulk handling industry. “Bulk Handling Today” speaks to Michael Gullick of Hägglunds Drives South Africa about this technology now available in South Africa.

“Today you’ll find our reliable drive systems in all types of materials handling applications, includ-ing conveyor drive and conveyor belt tensioning systems,” he says. “We have recently developed a new powerful motor range, the Compact CB, a motor ideal for use on apron feeders and bucket wheel reclaimers, for instance.”

New facilityThe South African office has only been active for four to five years and started off just doing sales, but since 2008 the local company has grown in leaps and bounds. “Because of the high demand, we’ve just launched a new service facility which was only planned for about five years’ hence,” Michael says. “Where we previously sourced out the service requirements for drives sold here, we now do it all in-house as a complete drive solution.”

At the new facility, the company’s existing warehouse has been upgraded from 300 m² to 675m² and features a clean room, a ten tonne ton overhead crane, spray booth and a showcase test unit. “This new section is focused specifically on customer service and after sales support with additional

stockholding capacity and improved efficiency on repairs and projects,” Michael adds.

Same warranty“We’re supporting our high quality product range with a range of back up services to ensure that our customers enjoy the best possible turnaround times and quality of service. In addition, we now offer full repair services on motors and pumps, whereas we had a limited capacity before.”

Additional services include system diagnostic checks, preventive maintenance, emergency re-pairs, service contracts and agreements as well as customer training. “The repairs we undertake carry the same warranty as new equipment, and the field service is available on-site and round the clock,” Michael elaborates.

“The quality of our service is guaranteed through

Fluid Power

Michael Gullick of Hägglunds Drives South Africa

A fundamental feature of a hydraulic drive is the high torque that can be obtained from a dimensionally small unit when it drives heavy rotational equipment at speeds below one revolution per minute to above 320 revolutions per minute without the need for mechanical gears. This powerful mechanical force makes it possible to optimise the design of large heavy machinery.

Driving a bucket wheel excavator

We now do it all in-house as a complete drive solution


The hydraulic drive on conveyor application

our innovative new equipment and professional staff who have been trained by Hagglunds Drives industry specific experts. Our global organisa-tion has skilled and knowledgeable service staff across the globe who have a solid understanding of hydraulics and are often specialists in specific applications.”

ReclaimersOn bucket wheel reclaimers, the Hägglunds hydraulic direct drives offer many important features resulting in vast improvements in performance, because the

The new service centre in South Africa

hydraulic motor is installed directly on the wheel shaft and has built-in overload protection, eliminating trip outs. This, in case of a stalling, minimises valuable production losses.

“The drives, having extremely low inertia and weight, reduce the stresses on the boom and slewing gear,” adds Michael. “They also provide full torque throughout the infinitely variable speed, thereby optimising performance for different materials and conditions.

Excavators and bucket feedersHigh shock loads, vibration and dusty environments are some of the conditions a bucket wheel excavator drive has to contend with. “Hydraulic drives are ideal for this type of heavy-duty shock load application,” says Michael. “The motor can be mounted directly to the bucket wheel shaft without the need for a gearbox or any foundation.

To optimise the production rate on belt feeders, the speed has to vary continu-ously, which is a very demanding require-ment for any drive system. “Without effort or excessive strain, the speed on a hydraulic drive can be altered as often as required,” Michael explains.

“The drive can even stop and start without any limitations and under the roughest conditions. Feeders are usually installed in areas where space is limited, but hydraulic motors in general, compared with an electro-mechanical drive train, are very small and require minimum space at the drive pulley. Our Compact series was developed specifically with this in mind, bringing maximum power but requiring minimum space.”

Apron Feeders“These benefits also apply to apron feed-ers where you need a robust drive with variable speed that has to start up in any load condition,” adds Michael. “Our

hydraulic motors have the ability to provide full starting torque without time restrictions. Usually electro-mechanical drives in this application have to be over-specified to cope with the load, which requires more electricity.”

Belt conveyorsHägglunds also has conveyor belt tensioning capabilities whereby a hydraulic winch assembly is coupled to a closed circuit hydraulic system. Michael elaborates, “In this way, a set pressure

POWER TRANSMISSION

Hydraulic drives are ideal for this type of heavy-duty shock load application


is maintained and, therefore, constant belt tension without the need for load cells, accumulators or limit switches, while gearboxes are eliminated. The result is a reliable, compact and fast responding heavy duty winch assembly with a low inertia.

“In a belt conveyor drive configuration, our hydraulic drives offer a high starting torque which can be achieved without any time restriction, which allows clients to cater for unusual conveyor loading,” adds Michael. “The time to ramp up to full speed can be set to whatever is required. Soft starts and stops reduce the stresses in the belt to a minimum and the pressure control protects the belt from any overloads. If you need to inspect the belt, the drive can be set at very low speeds and inched forwards or backward to enable easy inspection.”

Less stressIn essence, a complete hydraulic drive systems has no need for reduction gearing at all because the speed of the drive is directly related to the flow from the hydraulic pump in the system and therefore

The test bay at the new service centre in South Africa

the power, speed and torque are easily controlled,” says Michael in conclusion. “The hydraulic closed loop system provides a highly dynamic four-quad-rant drive with driving and braking in forward and reverse. Most importantly, quick pump pressure control minimises unwanted transients of stresses and strains on the driven machinery.”

Michael Gullick, Hägglunds Drives, Tel: (011) 454-4933, Email: [email protected]

POWER TRANSMISSION

The time to ramp up to full speed can be set to whatever is required

�0 BULK HANDLING TODAY June 2010

The beat goes onThe 2010 Soccer World Cup will offer many challenges for the operations management profession. But what happens when it is all over?Supply Chain and Operations Management professionals must maintain a steady, reliable beat as we continue to move African industry forward to ensure our sustainable footprint.

25 - 28 July 2010 Sun City

The SAPICS Annual Conference is the Leading Event in Africa for Supply Chain and Operations

Management Professionals.

32nd Annual Conference & Exhibition

T 011 023 6707, F 086 575 2979 or [email protected]. www.sapics.org.za

With the participation of: Principal sponsor:

Silver sponsor: Gold sponsor:

Platinum sponsors:

BULK HANDLING TODAY June 2010 �1

“We have taken shuttle car suspension technol-ogy to the next level,” says Adam Peterson, Group Leader Haulage Hydraulics of Joy’s Haulage Engineering Department.

Taken up a notch“Joy Mining Machinery has offered a four-wheel independent suspension system as an optional feature on shuttle cars for more than ten years,” Adam adds. “What has taken this system up a notch is the new Joyride strut incorporated into the suspension system.”

A standard Joy shuttle car without four-wheel suspension uses a pivoting axle supporting the machine’s discharge end wheels, and fixed axles on the loading end. The optional four-wheel suspension system, introduced a decade ago, is a passive strut system incorporating internal elastomeric pucks and spacer plates designed to last until the next

To a New LevelThere has been a breakthrough in underground wheeled haul-age technology with the development of the “next generation”

in shuttle car suspension—Joyride, the industry’s most ad-vanced four-wheel independent suspension system.

machine rebuild, then to be discarded.

Full year of testingThe new Joyride strut system, with its patented technology significantly reduces forces on the suspension and offers the best-in-class ride today. “The strut is a product of one-and-a-half years of design, component testing, and underground ma-chine testing,” says Adam, “including a full year of testing at Foundation Coal’s Emerald Mine in Waynesburg, Pennsylvania, USA.

“The timing for the project was right,” he adds. “Our customers had been asking if we could improve the current strut system to facilitate rebuilding, and Joy’s haulage engineering group was strategically driving the need to optimise the design characteristics to enable improved performance.

Can be retrofitted“The new struts can be retrofitted to suspension machines in the field today and a new chassis is not required to do so,” Adam explains.

While productivity and performance were the main focus of the new strut development, the goal was to have the best-in-class ride and to “separate Joy from the competition” by using technology that would provide real value to the customer.

JOY 10SC32 shuttle car with the Joyride shuttle car suspension system

HAULAGE TECHNOLOGY

Reduces forces on the suspension and offers the best-in-class ride today


According to Adam, “Joyride’s added value includes superior dampening characteristics that reduce forces on the machine chassis resulting in increased opera-tor comfort, reduced loss of material and less rutting in roadways. This results in greater utilisation of Joy Optidrive’s speed capabilities and allows increased productivity and an improved bottom line, as has been proven in cars already operating underground.

More trips per shift“A good analogy would be if you were driving on a bumpy road and the suspension system on your ve-hicle performed well. The impact of the bumpy road would be minimised and the speed of the vehicle could be increased. With shuttle cars, that means more trips per shift, which means more coal per day at a reduced cost to the operator.”

The company first offered this suspension system on its 10SC32B model, recently extending it world-wide to most mid and high-seam models. In total, the company offers eight different shuttle car model variations ranging in capacity from 8 tons (7 tonnes) to the industry’s only 33 ton (30 tonnes) machine. The 21SC shuttle car series is designed for low coal and the 10SC series for medium and high-seam.

Nothing comparableWhile there are others who offer shuttle cars with suspensions, Adam says none of them utilise any-thing comparable to their patented strut design. “A key goal in the development of the new strut was to provide the best-in-class ride design,” he adds. “We hit our desired target. Additionally, our customers also have the capability to retrofit their existing suspen-sion machines at rebuild and underground with our suspension strut technology without having to make chassis design changes.”

The first Joyride equipped shuttle car was shipped in January 2009 to Consol Energy’s Enlow Fork Mine in West Finley, Pennsylvania, USA.

“More than 30 shuttle cars with the Joyride strut have been sold since its introduction,” Adam elaborates, “and hundreds of these struts have been manufactured to date, more than half of them being purchased for retrofitting existing four-wheel suspension machines in the field.

Many firsts“We excel in both innovation, and the development and implementation of new technology,” Adam says proudly. “Take shuttle cars alone—of which there are more than 2 500 operating worldwide, two-thirds of them are Joy’s. We were the first to apply AC/DC drives and the first AC Variable Frequency Drive (Op-tidrive); the first to have remote control capabilities, the first modulating valve braking system, the first ergonomic form-molded foam operator’s seat, the first passive four-wheel suspension system and, now, the most advanced four-wheel independent suspension system, Joyride.”

Joy, Tel: (011) 406-6100, Website: www.joy.com

HAULAGE TECHNOLOGY

BULK HANDLING TODAY June 2010 ��

Tyre pressure-monitoring deviceA heavy vehicle accessory which monitors tyre pressures on trucks, trailers and buses is playing a significant role in improving safety on roads in South Africa.

Marketed under the brand name P-Eye, the state-of-the-art device replaces the tyre valve cap monitoring preset mini-mum tyre pressure – if the pressure drops more than 5% below the required setting, an LED lamp starts blinking. This makes it a relatively simple task for commercial operators to establish tyre pressures on their fleet, as a visual check on any vehicle fitted with the device quickly reveals whether tyres are all correctly inflated.

The system is thus both safer and more cost efficient than

Overhead crane deal Crane specialist GM Technical Services (GMTS), based in Vereeniging in the Vaal Triangle, has concluded an agreement with Street Crane Company of the United Kingdom to bring advanced overhead crane and hoist technology to South Africa. The deal underpins employment, gives GMTS an opportunity for further growth and the capability to offer a complete range of cranes up to 50 tonnes safe working load.

George Mackenzie, founder and managing member of GMTS comments, “We are pleased to announce our association with Street Crane, the largest factory crane manufacturer in the UK. The deal allows us to tap into 60 years of expertise in all branches of industry and access their class leading ZX series hoists. Paired with locally engineered crane beams, the ZX hoists will enable GMTS to offer customers high performance cranes for greater productivity.

As the main distributor for Street Crane products in South Africa, GMTS will not only be supplying end users but will also be able to supply crane service and repair companies throughout the country with Street hoists or cranes that have been fabricated locally. Hoist components will be held in kit form for rapid assembly to meet local needs.

Street Crane has invested heavily to develop the advanced ZX series hoists for world markets. Modular in construction, the ZX is easily custom-ised to meet differing end user requirements and national standards.

Commenting on the deal, Street Crane’s managing director Andrew Pimblett notes, “South Africa is a huge potential market. GMTS is a partner with in-depth engineering experience and capability. We have similar arrangements with over 50 national

Market Forum

Concluding the crane deal, left to right, is Andrew Pimblett managing director of Street Crane Company with Mark Mackenzie and Hannes Steenberg of GM Technical Services.

and regional crane makers around the world and I am confident that the relationship will prove mutu-ally beneficial to our companies and to our end-user customers in South Africa.”

GMTS has a long association with DSE, the largest fabricator of structural steelwork in South Africa. Several large cranes have been supplied over a number of years. The first two Street branded cranes, units of 10 tonnes SWL, were shipped to DSE in April.

George Mackenzie, Tel: (016) 428-1462, Fax: (016) 428-1072, GM Tech-nical Services, Web: www.streetcrane.co.uk, E-mail: [email protected]

Preggie Govender & Phumlani Bayeni of Serco with a newly fitted p-eye tyre pressure monitor

�� BULK HANDLING TODAY June 2010


Largest in the world!KEW Foundries, a Kimberley-based engineering works, has a rich heritage in the manufacture of steel works for the mines. The first truck to bear the Freightliner nameplate appeared in 1942. Due to the extensive use of aluminium the early Freightliners could carry almost a metric tonne more than any other truck on the road.

“It is thus fitting that Kew Foundries has selected the Freight-liner Argosy Cummins 500 as their ‘abnormal load’ truck of choice,” says Duncan Prince, Product Manager, Freightliner/FUSO – division of Mercedes-Benz South Africa.

KEW Foundries are delivering the largest cast sheave wheels

Outstanding innovations HBC-radiomatic, the world’s leading manufacturer of radio controls for industrial applications, is now presenting numer-ous innovations.

The new version of the HBC-radiomatic micron 5 hand-held transmitter for the control of cranes and other machinery

Market Forummanual checks as it is not necessary to check every single tyre, with action necessary only when the LED’s are blinking. Research has shown that about a quarter of all commercial vehicle tyres are not sufficiently inflated, increasing wear by about 15% to 20% and fuel up to 7%. It is also commonly known that many blow–outs and tyre stripping are caused by under inflated tyres, sometimes with devastating and fatal consequences.

Add to that the fact that under-inflated tyres have a greater rolling resistance and hence burn more fuel and money and emit more carbon emissions into the atmosphere, and P-Eye’s road safety, cost-saving and environment-friendly qualities become abundantly clear. South African truck and trailer manufacturer, Serco Industries, has been awarded the sole agency to market P-Eye in Southern Africa.

Serco, Clinton Holcroft, Tel: (031) 508-1000, Cell: 082 453 4436

in Africa to their mining customers. The sheave wheels, with a root diameter of 6.5 m, will be installed as deflector sheaves on mining shafts, and will enable personnel and ore to be lifted from a depth of 1602 m below bank.

“As mines get deeper, larger sheave wheels are required to achieve a greater payload for each winding cycle. Tradition-ally sheave wheels of this size are fabricated from welded steel sections.

KEW Foundries, however, is the only company in the world with the capabilities to cast and machine sheave wheels of this size. Cast sheave wheels offer significant cost savings to clients over their fabricated counterparts,” says Jaime Goncalves, Technical Director, KEW Foundries.

The Freightliner Argosy Cummins 500 is an ideal vehicle to accommodate our purpose built sheave wheel 33-tonne trailer and allows the company to transport these monolithic sheave wheels into Africa without an escort. In compliance with the road act, we do however, obtain special abnormal load permits, which allow us to travel in daylight hours only,” Jaime concludes

Shirle Greig, Tel: (012) 677-1904, Fax: (012) 677-1682, E-mail:[email protected]

�� BULK HANDLING TODAY June 2010 Advanced Materials Today September 2007 39

AMT Sept 07 zin.indd 39 2007/09/11 10:28:49 AM


will now offer numerous new features, allowing for even more applica-tion possibilities. Along with 10 two-step push buttons, the new version comes with a rotary switch. Radiomatic iLOG is also standard. The electronic key enables the quick activation of a spare transmitter if the radio

control is damaged. A further benefit is the powerful NiMH rechargeable battery with approx. 30 hours of continuous operating time (standard version).

Another major highlight of the new micron 5 is the approval for use in hazardous environments, such as Ex zones 1, 2, 21 and 22. Adding the hand-held trans-mitter to the impressive line of controls for hazard-ous envi-ronments s h o w s why HBC-radiomatic

is the world-wide leader in wireless safety. Further new options are the vibration alarm and the user identification.

An outstanding innovation for crane con-trol, is the new spectrum D transmitter. In addition to the numerous functions of the spectrum series, this powerful device comes with a 3.5” color TFT screen. The display is non-reflective, allowing for perfect clarity, even in sunny conditions. In addition, the TFT is equipped with QVGA technology and boasts a color depth of 18 Bits including an extensive internal memory, enabling the display of various graphics, image files and language versions.

Bexl Control Systems cc, Tel: (011) 421-0004/25, Fax: (011) 422-2571,Email: [email protected], Web: www.bexl.co.za

Market Forum

Belt seriesSKF are proud to introduce the newest additions to their power transmission family of high quality products.

SKF Xtra power belts are designed to deliver up to 40% more power than standard wrapped belts. These belts will not only cut costs but more importantly extend the service life of existing applications. An increased service life and

less downtime equal less cost!

Varma Parag, SKF Platform Manager, Power Transmission, explains the advantages, “The Xtra power belts are homoge-neous and have a coordinated integration of the belt, flank and the pulley groove. They reduce pulley groove wear due to optimized cover fabric and offer up to 97% drive efficiency. They are also oil and heat resistant and have an antistatic cover. You only have to worry about one-shot tensioning, and there is no need to re-tension the belts after the initial run in period. They also have improved smooth running behaviour, low vibration levels and offer good resistance to shock loads”.

Tension members for the Xtra power belts are polyester and specially treated providing high tension loads and low elongation. A fibre filled compound above and below the tension members allows the belts to carry higher dynamic loadings with no compromise of flexibility and full support of tension cords. The cover fabric provides excellent wear and abrasion resistance while also providing excellent bend-ing strength.

The SKF Xtra power belts further supplement the existing Power transmission range and support SKF’s strategy to offer value added products to its customers.

SKF South Africa (Pty) Ltd,Samantha Joubert, Tel: (011) 821-3500, Fax: (011) 821-3501, Email: [email protected], Web: www.skf.co.za

Advanced Materials Today September 2007 39

AMT Sept 07 zin.indd 39 2007/09/11 10:28:49 AM

Log onto www.promech.co.za to read

back issues of ‘Bulk Handling Today’

�� BULK HANDLING TODAY June 2010

Market Forum

Afzelia 34

AST Inside Front Cover

Bearings International 18

Bonfiglioli Inside Back Cover

Brelko 23

Dymot 20

Engineer Placements 32

Hägglunds 14

LMI Academy 12

Rema Tip Top Outside Back Cover

RFA 8

Roymec Outside Front Cover

SAID 36

Sapics 30

SEW 26

Short-term Stay 38

Silver A 16

SKF 10

ThyssenKrupp 25

Voith 6

Index to Advertisers

Please fax us if you wish to subscribe to “Bulk Handling Today” at

R400,00 (incl postage and VAT) per year; R945,00 per year for Af-

rica/Overseas. We will post you an invoice on receipt of your fax.

PROMECH PUBLISHING Fax No: (011) 781-1403

Email: [email protected]

From:.........................................................................................

(insert your name)

Title: ..........................................................................................

Company: .................................................................................

Address: ..................................................................................

....................................................................................................

......................................................................Code: ..................

Telephone: (.......) ....................................................................

Fax: (.......) ................................................................................

Email: .......................................................................................

SubscriptionBeam loadcellInstrotech offers a new miniature double ended beam load-cell for application in truck/rail scales and silo/hopper/tank weighing.

The MDB is designed for high capacities of 10t to 50t and is insensitive to side load. Constructed of nickel plated alloy steel, the unit is fully potted and sealed with special chemical compounds to IP67 providing excellent protection against the ingress of water and moisture.

The model MDB can be supplied optionally hermetically sealed to IP68 to protect in corrosive environments and under washdown conditions. Another available option is FM approval: intrinsic safety in Class I, II, III Div I Groups A-G or non-incendive in Class I Div 2 Groups A-D.

Instrotech (Pty) Ltd, Tel No: (011) 462-1920, Fax: (011) 462-1958, E-mail: [email protected], Pieter Deysel



Documents

BHT: Jun 2010