LanceRobson

This is a great example of why the military selects and train "operators", not "drivers". I'd suggest you leave the winch alone until you learn how to use it. You're going to damage it or get someone hurt.

The vehicle operator's manual clearly states that the winch will only provide it's rated pull with a nearly empty drum. Every layer of cable means that more cable is pulled in for each drum revolution and the winch is operating at lower efficiency.

Think about the load you were trying to pull. Let's say the truck weighs 20,000 pounds. It has 20,000 pounds of gravel in it for 40,000 pounds total. If it is mired to the axles (or close to them) it will take up to it's own weight of line pull to free it. If he can spin his tires (slowly) to help that will reduce some but not much.

You were asking the winch to do something way beyond it's ability. The shear pins did exactly what they should have-they sheared before you broke the winch or the cable. A 10K winch with most of the cable off the drum and a snatch block is still only going to have 20K of potential from which you subtract friction loss in the block. Even with a snatch block the winch was overloaded.

You need to have nearly all of the cable off the drum and have a straight pull to a load that is being pulled straight at you to get the full rated capacity from the winch. If you can't do that, use snatch blocks to get the fleet angles right or to help get the cable off the drum. You may have to move your truck and re-rig every 25 feet or so the keep the drum nearly empty.

Download FM 21-20, Recovery Operations, from the resources section or buy a copy. After reading it, put it in your glove box or pamphlet bag with your heavy leather gloves, a punch (to remove broken pins) and a hammer.

Lance

Billy Bobbed

WINCH FOR SALE.I dont know how to use it.Read your owners manual before useing it.

__________________
M105A Trailer (FOR SALE)

gringeltaube

If you mean shear strength.... I used to think the same until I did the testing:
The final torque value to breakage was about the same for a given material; pin fitted tightly into a cylindrical hole vs. same pin in an oversized, deformed hole.
Maybe its comparable to cut (shear) material with a sharp pair of scissors vs a dull one...?

G.

stumps

Hi Gringeltaube,

I have no doubt that the pin's shear strength in a carefully controlled one time experiment is nearly the same...

But,

I think you will find that shear pin longevity drops drastically with a wallowed out hole. The lost motion caused by the wallowed out hole lets the pin go to one extreme of the hole when you unwind the winch, and to the other when you wind with the winch. Each time it travels through the lost motion, the hole takes a hard whack at the pin, and the pin gets hammered thinner.

-Chuck

gringeltaube

Good point Chuck! I really didn't think about rocking the long lever back and forth x-times before applying ultimate torque to the point of shear...

But.... do we really see any significant torque in the opposite (reverse) direction, despite the force to overcome the band-brake???
And if so, would it really be an instant full load as to cause that "hammering" condition everytime we shift the PTO into reverse, especially if on the wind-in side the load (under normal working conditions) will increase gradually also???

Certainly it would be difficult to reproduce exact real working conditions during such a quick test...
At least with what we do know already, everybody can easily make- or have access to- "adequate torque-" replacement pins, cheap enough to carry at least half a dozen spares in the glove box, just in case...

Against your statement "if the holes that the winch shear pin fits through are wallowed out in size, you are never again going to get good service out of a shear pin"..., I say again that the max. torque we can expect from such a pin replaced and immediately put to service at extreme load (typically after the first one has sheared amidst a recovery operation) will mainly depend on material and diameter of the pin, not so on the hole's condition, according to my tests...

To all: drive and winch SAFELY!!
G.

Ronbo

If any one gets/ makes any pins as stated earlier please shoot me a pm .I'd buy 1/2 a dozen to keep on hand .. Thanks

stumps

Every time the PTO is unloaded (clutch in, neutral, whatever...), the entire drive chain relaxes. A loose pin will seek a neutral relaxed position in its hole. When the PTO again takes a load, the pin will move freely in the wallowed out hole, building up inertia, until it gets hammered when the slack is taken up.

This happens a lot in the Ag world where the costs of owning and operating machines are a major hit on a tiny profit line. The machines get run into the ground, resurrected by whatever means, and then run into the ground again. Shear pins seem to always get replaced with grade 8 bolts, or hardened pins, further wallowing out holes. If you ever go back to the proper shear pin, it gives up quickly.

-Chuck

colsoncj

Does anyone know the spacing between cotter pin holes? (trying to figure out spec on length of pin.)

gringeltaube

Total length is 2-3/8", c-c distance between holes is 2-3/16", hole diam. = 2mm.

G.

colsoncj

Perfect Information. Thank you.