Chain Hoist

David gave me his old chain hoist last year, and only this month have I found it buried in a pile of stuff at the back of my shed. I oiled the wheels as best I could, hung it from a rafter to test it out, then made a tripod of beams and pulled the three-feet of buried rod that was used as a ground rod for the original wiring system for the house.

My first real job is to pull an old clothes-line post from the ground. The pole is rotted or snapped near the point where it meets the ground, so a manual rocking to and fro or trying to yank it out would probably snap the pole off at ground level, making recovery difficult.

The answer is to use what tensile strength is left in the pole and haul it out vertically and smoothly.

In the image above you can see that I have set the tripod away from the pole, and have hooked the block to a beam laid horizontally. My theory is that I can gain leverage with that horizontal beam, about 6:1 by the looks of it in the image, and this multiplies the mechanical advantage of the chain hoist. If the chain hoist gives me 10:1, then the beam and hoist gives me 60:1.

That means that I can apply more force more smoothly, but it means that I will spend six times as long actually applying the force. I don't mind that time. I will be spending two or more hours learning this morning, so an extra ten minutes is not a big deal

I have looped five feet of chain around the top of the tripod; the block will be suspended from this loop.

When I make my real tripod, I will use strong chain both to hold the beams together and to suspend the block. I might be brave enough to thread the chain through each beam.

The hook chain is looped around the lifting end of the beam and the hook is secured to the chain.

At the far end I have laid a stout plank to serve as a fulcrum base, to stop the end of the beam sinking into the soil.

A few spare blocks of wood wait to be slipped under the toe of the beam if needed to add height.

A second five-foot length of chain is used to strap the beam to the pole.

Here is an overall view. I have yellow-circled the toe of the beam. Further I have raised the working end to bring the whole scheme into tension. Will I be free of that pole within five minutes?

The chain binding the beam and pole slipped, so I blocked up the toe (fulcrum) of the beam and tried again.

I moved the tripod a bit so that the block was not rubbing against a leg. A Bit? I rotated the tripod about sixty degrees to locate the block midway between two legs.

A view from outside, looking along the beam towards the pole. The loop of chain awaits the block, then we will lift the pole out of the ground!

The block is hooked, ready to go ...

I am proud to have the block hooked so that the load bears down on one leg of the tripod, tightening my cable that holds the apex of the tripod together.

Now we are talking, talking disaster. Because the block is hooked at or beyond the outer leg, the horizontal component of force serves only to lift the feet of the other two legs. Path-of-least-resistance, you might say.

Take it apart and secure the block loop inside the apex of the tripod.

Now the pole will lift out of the ground.

No. My loop that straps the beam to the pole has slipped upwards. Sigh. I will lower everything and pass a few nails through links of the chain in an effort to stop them slipping upwards.

That, or I need a longer chain, thinner perhaps, with a few loops around the pole, loops which cover each other and bind themselves in place, and only then a few loops around the beam, loops which cover each other and bind themselves in place.

My original idea used strong electrical cable whose insulation provides a good frictional grip.

Almost an hour has passed since I started assembling material; I am still wearing my paint shirt over my work shirt; I am hot. I retire inside to write up my work so far and take a rest.

Thursday, December 28, 2023

I have seen a better idea than a bulky chain-hoist; use a car-jack (scissor or hydraulic) with a wrapped chain, and jack the post out of the ground.

Sunday, January 14, 2024

For rope pulley systems, see Prusik Knots

Also see Nifty Lift

Search