4 speed reverse gear. (Warning Big Pics 1.2 meg

Anybody know what they are telling as to the failure mechanism?

Oh, (sheepishly) with the new gear on the mainshaft, I set the preload and had my buddy a former hvy eq tech check. He had me take out 2.5 mils of shim. The new shim pack is thinner than the old one that was in there when it broke. How much thinner? 0.0615 worth of shim was taken out. I really blew it first time around.

Buddy showed me a "trick". with a rubber hammer, tap the gear cluster to the back while pushing it back with finger pressure. Then with a finger on the side of the output shaft, tap the end of the shaft with a 3 lb hammer with a dead blow action. You can clearly feel any motion. Doing it with a dial indicator on it will show any motion. A dozen taps should show no more than a couple mil of total motion. If it has more, something wasn't bottomed and is allowing motion. Had I done that before... oh well. Live and learn, die and forget it all.

jb

Found the root cause of the failure. I still should have found it before, but it is at least subtle.

In putting the transmission back together tonight, the gears would not spin freely. After much head scratching and investigations, the main gear cluster shaft is bent. The very end of it that mates with the input shaft (or on my tractor, the Sherman transmission) is bent. How much? The tip is wobbling by 0.035" and is only 1" or so long, so it's bad.

Of course, now I need the shaft, but once that is in, it should be good for a long time.

jb

I think it was bent before. I also think that it caused me to shim in loose when I built it before.

Now to find one...

jb

So long as you're sure that that's what was wrong. My first thought would be that it bent when everything locked up. BTW, the teeth look to me like they failed from pure overload. That's how they look in planetaries when they break on me.... It might not hurt to doublecheck further down the line to make sure there's nothing wrong in the rear end, or that it didn't just pick up some metal in a tooth somewhere. That's all it would take to lock something solid.... and you know what happens then. I would also check all the shift rails and the gear shift lever itself for wear. If it got jammed in two gears at once, then bang. I've seen 18 speed Roadrangers that have done that at highway speed, hauling a loaded tri-axle. You can imagine what that looks like. They didn't even get to reuse the case.... The only other suggestions I could make are to follow your book closely, and if something doesn't quite go, or doesn't fit right, stop and ask why. I would think that everything should fit together properly. I know there was some discussion about ill-fitting parts a few days ago, but if it was me, and something didn't fit, I'd be more inclined to wonder what I did wrong first. I've made stuff fit before, and found my mistake later..... Somtimes the obvious evades us... Good luck.

Rod

Good suggestions. This trans was in a sad state when the tractor was originally purchased. Prior owner had just bought it at and was going across a field to use the backhoe and got stuck in early season mud. Rather than walk out using the hoe, he put chains on the tires and was rocking it out. Well, attempting to anyway. There was pretty much mass destruction of the countershaft, reverse, countershaft 2nd, main 2nd, main first, main 3rd and the output from the sherman. There was a pocket full of busted teeth at the bottom of the trans.

I fixed all the gears and stuff, but missed the bent nose on the output shaft. Thinking back, I did feel the bind and must have figgured that it just needed more shims. (yeah I know --> brain dead)

Oh well, you're supposed to learn more from mistakes than from success. If true, I'm on the way to a PHD!

jb

Just imagine yourself like the Wizard of Oz. Someone got a question about a 4 speed? Ask if you may address that problem to the all great and powerful PHD JB!!! He will check and see if his schedule allows him time to consider your trivial problem!

And PHD stands for "Piled Higher and Deeper"

Sumpin Dun Broke!

Now for my next trick, I'll try and put it back together again!

jb

I had posted a couple times on this and forgot to put in those details (sorry!)

The tractor is a 1963 Ford 4140 HD Industrial 172D engine. With loader and 14' hoe attached. Tires are 16.9x24 R4 - not filled no wheel weights. Sherman trans was in underdrive. The clutch and PP are new (30 hours), it does not grind.

The tractor was backing up out of it's own tire pocks, a tire started slipping and the brake was pressed. BANG! Trans broke.

The blue is just the oil sheen on the teeth.

Thanks,
jb