A Backwoods Home Anthology

359The Best of the First Two Years

(Accomplishing heavy tasks withoutmachinery is often a challenge in rural areas.Hence this series by Don Fallick. This is thesecond part; the first appeared In Issue No.8, the March/April 1991 issue.)

© By Don Fallick

o m e o f h u m a n i t y ’ s e a r l i e s tmechanical contrivances involvedways of using rope to lift or pullheavy objects. Anyone who’s everhauled water buckets out of a wellhand-overhand has probably saidsomething like, “There’s got to be abetter way to do this!” Well, there is.In fact, there are several.

The PulleyPulley wheels have been in use so

long that their origin is lost in themists of antiquity. We do know thatthey were used by all the ancient civi-lizations of Asia and the Middle East.Some archaeologists now believe theymay also have been in use in theAmericas in pre-Columbian times,though wheeled vehicles apparentlywere not.

In its crude form, such as a ropethrown over a tree limb, the pulley is avery simple device, used only tochange the direction of pull. Pulleys ofthis sort were probably used by cave-dwelling hunters. Anyone who hasever tried to lift even a small carcassfor cleaning and skinning can appreciatethe usefulness of such a simple pulley.

In mechanical terms, a pulleychanges the direction of pull from upto down, increasing our effectivestrength by adding the force of gravityto the force of our muscles.

A simple system like this has threelimiting factors: the friction of the treebranch, the breaking strength of therope, and the weight of the person. If

we substitute a pulley wheel for thetree limb, we can greatly reduce thefriction, and also reduce the chance ofthe limb breaking. Breaking the ropeis another matter. A rope is rated byits ult imate load—the maximum,steady weight it’ll hold without break-ing, and also by it’s working load,

which allows for some stretching, tug-ging, and bending.

In purchasing rope, always go by theworking load, then allow a generoussafety margin, say 50% or more. Remem-ber, ratings only apply to new rope.

Your weight is also a limiting factor.If you are trying to lift a 500 lb. autoengine, and you weigh 180 lbs., youcan pull as hard as you like, evenclimb the rope, and the engine won’tbudge, because the total downwardforce on your side of the pulley is lessthan the total downward force (theweight) on the engine side.

One way to increase your effectivestrength is to add weight to your sideof the pulley. A convenient way toadd weight to a rope is to tie cement

Make lifting easy with a rope

and the principles of “mechanics”

S

COUNTRY TASKS

Figure 1. The pulley.

A Backwoods Home Anthology

360 The Best of the First Two Years

blocks to it. They weigh about 40 lbs.each, so if you tie 10 blocks to yourside of the pulley rope, you can lift theengine with a 100-lb. pull. I have usedthis method. I have also used bucketsof water, lumps of metal, and piecesof dead machinery for counterweights.Once I used my pickup truck as acounterweight. More about this later.

Block and tackleYou may not always have a heavy

counterweight to help you. Well, ifyou have two pulleys, you can impro-vise a block & tackle. So far, we’vebeen discussing only systems in whichthe pulley is at the top. what happensif we attach one end of the rope to thetree limb at the top and hang theweight from the middle of the rope bythe pulley? Of course, we’ll now haveto exert force in an upward direction.But because the weight, hanging fromthe pulley, is free to slide, it only risesone foot for every two feet that we liftour end of the rope. So the force wemust exert is equal to only 1/2 theweight. If we add another pulley at thetop, and reverse the direction of pull,we’ll have a downward-pull systemthat doubles our effective strength. Infact, it doubles ANY force exerted on

it including the weight of inanimateobjects, so three cement blocks wouldexert as much force as if they weighed80 lbs. each, or 320 lbs. total. To figure

out what’s required for the lift, we canadd all the forces on our side of thepulley (our weight plus the blocks) andmultiply by our mechanical advantagefactor, which is 2, since we can lifttwice the weight with the same force.

3 blocks at 40 lbs. each = 120 lbs.us—average man weighs + 180 lbs

300 lbs.x 2 (advantage factor)

TOTAL FORCE: 600 lbs.

This is much more than the 500 lb.weight of the engine we want to lift.Actually, we only need to exert 130lbs. to lift the engine. But we can doeven better than this if we have threepulleys. If we tie one end of the ropeto the frame of the bottom pulley, andthread the other end through one ofthe top pulleys, then through the bot-tom pulley, then through the other toppulley, we can re-double our mechani-cal advantage.

We will have to pull four feet on ourrope to lift the engine one foot, butwill only have to pull ¼ as hard! So apull of 125 pounds could lift a 500 lb.engine without counter weights (seeFigure 1). Of course, you don’t haveto do the math to use the pulleys.

This principle was understood longbefore Roman times. No one knowswho first got the idea of combiningseveral pulley wheels into one blockof wood or metal, and, using two suchblocks, strung together with tackle

(ropes) for hoisting, but they havebeen used this way, all over the world,for millennia. I recently saw such ablock and tackle hoist, with a 16:1advantage factor in the automotivesection of a large supermarket. It wasrated at 1500 lbs. lifting capacity, andsold for $15, surely a terrific bargain.

The gantryWhen you need to lift something

heavy, you may not always have aplace to hang a pulley or a block andtackle. What you really need is somekind of instant crane.

One of the simplest such devices,and one of the most ancient, is thegantry (see Figure 2). In its simplestform, this is a pair of poles, fastenedtogether at one end to form a V. Arope between the top ends keeps the Vfrom spreading. The bottom of the Vis placed in a trench, to keep it fromfalling over sideways.

The weight to be lifted is suspendedfrom one arm of the V by a rope,while the other arm is pulled down bysome source of power or weight.When you pull down on one arm ofthe gantry, the whole thing pivots andpulls up the other arm. In effect, agantry is a kind of lever with a kink inthe middle. Like any other lever, wecan make the pulling arm longer thanthe lifting arm, reducing the effortneeded for the lift.

Figure 2. The gantry. Figure 3. Gantry with pulley.

Gantries can be made out of quiteflimsy materials. I have used 15-foot2x4s, with 8-foot pieces nailed to theircenters for stiffening, to lift quiteheavy weights. The weight of the loadis carried in tension by the rope con-necting the en& of the gantry arms.The poles carry the load only in com-pression as long as you keep themfrom actual ly bending. Wood isstrongest in compression. That’s whythe weight of a house can be carriedby the vertical 2x4s in the walls.

Gantries have been used in construc-tion for 4000 years or more, so I don’tunderstand why nobody thought ofturning one upside-down and makinga roof truss, but truss construction wasunknown before 400 AD, and didn’tbecome common until the Middle Ages.

If you’re going to do a lot of lifting,you may wish to make a more perma-nent gantry, by substituting upsidedown V’s for the poles. This type ofgantry is much more stable, and elimi-nates the need for a trench. The legscan be kept from spreading with ropeor another pole. A final refinement isto add a pulley or block and tackle tothe end of the lifting arm (see Figure3), so you can lift or lower your loadvertically, without horizontal move-ment. This makes it into a true crane.

The capstanAnother ancient device for increas-

ing the power of a rope is the capstan(see Figure 4). This consists of a log,or drum, which can be rotated, windingup the rope. Since the crank wasn’tinvented until the 14th Century or so,the ancients just drilled holes throughthe end of the drum and insertedspokes, like the spokes of a wheel,minus the rim. Nobody is really surewhether the spoked wheel inspired thecapstan, or the other way around.

Capstans can be very powerful.Each spoke can have a separate manor beast pulling on it, and the spokesact like levers, increasing the users’effective pull on the rope. A modernrefinement is to add a ratchet to thedrum, so it will turn in only one direc-tion, and another ratchet, attached to alever, in place of the spokes. Such a

device is called a “come-along” and isavailable where auto parts are sold.

Comealongs are rated by the weightthey can lift straight up, without dam-age. Repeated abuse will eventuallyrender them useless. When they break,they usually jam, making it real hardto remove the come-along. That’s whyI don’t buy used comealongs. Sinceweight on the ratchet makes it impos-sible to release, it’s a good idea tohave two come-alongs, anyway. Ican’t recommend using a come-alongas a hoist, since there’s no way to gentlylower the load after you’ve lifted it.

There are lots of heavy pulling jobsaround the homestead that don’tinvolve lifting. Unsticking a stuckvehicle is probably the most common.A come-along will do this just fine, aslong as there’s a tree or something toanchor the come-along to.

Even if there are no trees, you canstill use a come-along if you can makeyour own anchor, A wooden fencepost will work, if set two or three feetdeep, and angled against the directionof pull. Tie the come-along as low onthe post as possible. If the soil is softor the vehicle is heavy or badly stuck,the post may tear out anyway. To pre-vent this, set a “safety” post 5-10 feetbehind the anchor post, and tie the topof the anchor post to the bottom ofthe safety post.

If it still tears out, use two comea-longs, each with its own anchor postand safety post. If you hook bothcome-alongs to the vehicle, the postswill probably still tear out, becauseit’s almost impossible to get both rigsto transfer equal loads to their postssimultaneously. The total pull restsbriefly on each anchor alone, tearing itout of the ground.

A better way is to use a single tree, adevice used for hitching horses to awagon. It’s simply a three-foot-longpost with an eyebolt or hook in eachend, and another through the middle,facing the opposite way. The middlehook is fastened to the vehicle, andthe ends to the come-alongs (or hors-es). Because it’s not fastened rigidlyto the load, but is free to swing, thesingle tree keeps the pull on both

comealongs, equal. Thus the stress oneach anchor is halved.

Another good use for a come-alongis removing tree stumps. The key tothis trick is to make the stump as tallas possible. In fact, it’s best if you canpull the tree down whole. The weightof the tree helps a lot in levering thestump up out of the ground.

If you can’t leave the tree whole, atleast leave a good, long lever—six oreight feet of trunk is not too long.Securely fasten a rope as high on thetree trunk as you can. Then dig aroundthe surface roots near the tree andchop through them with a mattock oran old axe.

The dirt on the roots will quicklydull an axe, so you’ll have to spend alot of time resharpening it. A “dull”axe that bounces off wood can still beplenty sharp enough to take a bite outof your leg, so it pays to keep theblade sharp. Never pull a tree towardyourself.

Always use a pulley tied to anothertree.and pull at right angles to thedirection of fall. I have seen peoplepull trees toward themselves, whenthey thought they had plenty of room.

One of the hardest judgements tomake is the actual height of a standingtree. And catching a couple of tons ofwood in your lap can spoil your wholeday. Rig your come- along to a chain,tied to your end of the rope, and wear

A Backwoods Home Anthology

361The Best of the First Two Years

Figure 4. The capstan.

the same hardhat and protective gearyou’d use cutting timber. And whenthe tree starts to fall, GET OUTATHERE PRONTO! Felled timber hasthe cut to guide its fall . A treewrenched out of the ground by itsroots has nothing to guide it butgravity,, and its irregularly shapedroot stubs may make it twist and turn.Don’t depend on the rope to pull itstraight down. Once the tree starts tofall, the rope is slack. Of course thetree will probably be pretty close tothe ground before the roots let go,depending on the weight of the tree,the soundness of the remaining roots,etc. So it’s not likely to fall far out ofthe path you’ve chosen for it, But Iwouldn’t bet my life on it.

ImproviseJust when you need a hoist, pulley, or

a come-along most, you probablydon’t have one, right? Wait a minute.Maybe you do…if you’ve got a rope anda bumper jack. The ratchet of abumper jack is quite strong. Strongenough to lift one end of a truckweighing a couple of tons right offthe ground.

The. trick is rigging it to pull insteadof lift . The vertical part of mostbumper jacks is a hollow, triangulartube. Thread your pulling rope

through this tube, from the top down,and out the bottom end. Then tie theend to something that won’t slip backinto the tube, like a large bolt. Tie theother end to whatever you want topull. You’ll need another piece ofrope long enough to fasten to your“anchor” plus about six feet. Thisallows enough room for the jack tooperate, plus two or three feet formaking a loop in the end.

If you know how to tie a bowlineknot, it’s a good one to use for makingthe loop. If you don’t know how to tieone, try this instead: double the end ofthe rope and tie an ordinary “over-hand” knot in it—the kind of knot youtie when you start to t ie yourshoelaces, or make the first half of asquare knot. This will leave a loop inthe end that won’t slip down, thoughyou may not be able to untie it afterpulling it tight with the jack. Slip theloop over the hook on the jack andyou’ve got a home-made come-along.

Depending on the geometry of yourparticular jack, the tube may tend towander around a lot as you tighten therope. Tying it to the anchor line with ashort piece of twine will help a lot.

One of the best features of this “juryrig!” is that you can use it for safe lift-ing, since the jack is designed for low-ering, as well as lifting. Just be sure topad any sharp places on the jack that

could cut the rope. The hooks of somebumper jacks can be quite sharp.

Pickup truckOne of my favorite devices for

increasing the power of a pulley is agood pickup truck. Not only can atruck pull l ike crazy, sometimesyou can use the truck’s weight toadvantage, too

Once I was cutting logs for firewoodon the “back” side of a ridge. The Itroad” was real steep and the tractionminimal. I knew I’d never be able todrive up it with a loaded truck. Afterseveral tries, I did get most of the upthe “front” of the r idge, where Iparked. I chained the logs togetherin a big bundle, and ran a rope overthe crest of the ridge to the truck onthe other side.

I was worried that my rope wouldfray on the rocky ridgeline, so I putlog rollers under it. Instant pulley! Asthe truck ran down, the logs roseeffortlessly up the steep ridge to thetop. From there it was easy to dragthem downhill to a place where Icould load them on the truck. Now Iuse this technique often, harvestingfirewood in locations that would be“impossible’, without a long rope andthe principles of Mechanics. ∆

A Backwoods Home Anthology

362 The Best of the First Two Years

A family outing at a remote swimming hole.

The powers not delegated tothe United States by theConstitution, nor prohibited byit to the States, are reservedto the States respectively,or to the people.

The tenth amendment to theConstitution of the United States

Here comes the orator! with hisflood of words and his drop ofreason.

Benjamin Franklin, October 1735