Engine Lift Winch Hoist Puzzle

[Tom Wesenberg]

Here's a couple pictures of the engine lift I made about 20 years ago to pull my Model A engine. I haven't used my differential hoist since I made this one. Two weeks ago a storm blew down a large tree in my back yard, and this is the last of the logs I have to stack. I'm wondering what the mechanical advantage (reduction ratio) is of this hoist?

The handle is 7" long.
The cable is being wound onto a 1" diameter shaft.
There is a gear reduction of 13 teeth driving 42 teeth from the handle to the pulley winding the cable. Hoist 1a.JPG
Hoist 1b.JPG

[DaWizard]

The advantage is not having to use your back to muscle that log around and about 3.23:1

[WMWS]

The mechanical advantage would be reduced as the cable builds up on the one inch spool.

[Tom Wesenberg]

The mechanical advantage would be reduced as the cable builds up on the one inch spool.

That's true, but I'm just thinking about the first layer over the one inch shaft.

[Tom Wesenberg]

This is a great hoist to work with because it takes very little effort to operate. The handle is 7" long, so it's turning in a circle with 14" diameter and winding the cable onto a 1" diameter shaft, so this part gives a 14:1 ratio, but there is also a 13 tooth gear driving a 42 tooth gear, so this gives a 3.23 reduction. Now, the lifting pulley has the cable anchored at the top, so this also gives a 2 to 1 reduction, so the overall reduction is 14 x 3.23 x 2 = 90.44 reduction.

As WMWS said, the reduction is reduced as the diameter increases with each layer of cable on the spool, but even at half the reduction, this type hoist takes very little effort to lift a heavy load. I have a hand crank winch on my car trailer, and it has a 2 speed selector, so even loading a car with locked brakes or flat tires isn't too hard a job.