Posted by Sherman in Idaho [108.162.246.24] on Monday, October 10, 2016 at 18:20:51 :
In Reply to: Re: LU4 Steel Worm Gear posted by Kaegi [108.162.245.16] on Monday, October 10, 2016 at 13:46:30 :
I believe those are made of powdered iron, compressed in a form and sintered, which is part of why they're cheaper than machined bronze gears. I rebuilt the MU2 winch on one of my beater M37s using a sintered iron gear I bought off of ebay for around $100 some years ago. I suspect it's the same gear and they're interchangeable.
My winch was worn out due to the bronze gear being worn down to knife edges. When I took out the drain plug, about a cup of bronze powder and water came out. The obvious cause of failure was no lube. The truck had spent time in Alaska in the military and then was at the Puyallup fairgrounds where I was told the winch was used to set up circus tents (I guess the elephants were on strike). I don't know if these iron gears are really better than the original bronze gears, but they're about 1/3 the price and probably plenty good for occasional use if kept lubed. I suspect that in a head-to-head stress and longevity test they don't hold up as well (or the whole winch including the worm doesn't hold up as well) as the bronze gear. Bronze has always been a lot more expensive than steel and if steel was good enough they would have never used bronze. The only other explanation is that the sintered iron, because of its porosity, holds oil so much better than bronze that it doesn't wear the worm as fast, even though it's harder.