Stuck Diff Lock

[abritton77]

I am writting this post to hopefully save sombody some trouble and or money if they have the same problem as I did. I bought a used tractor that I believe sombody modified the diff lock pedal so that it would not push down and over travel the shaft that sticks out to activate the diff lock. When they did this, I belive that solved that problem but allowed the diff lock shaft to over travel. They had a block under the pedal to prevent that, but when I asked the guy I got it from he said that it was ther to prevent you from hitting the gas pedal when you pushed the lever. I belived him, and we removed the wooden block so that I could try it out. I worked fine, so I thought nothing off it and bought the tractor. Later after I started using the tractor, I pushed the lever down while the tractor was in motion and the shaft would not come out and the tires were locked together. No matter what I tried I couldnt get the tires to unlock. Im a car guy and not affraid to tear into something, so I decided to fix it.

Heres what I figured out when I tore into it. The diff sits infront of the axle centerline and spins a splinned shaft on each side that turns 2 gears that spin the tires. There is a coupling that locks the 2 shafts together and rides on the right side shaft unless the pedal is pushed down. Tne right shaft has a groove cut verticly in the right shaft. The coupling has a roll pin that connects it to the shaft that pokes out the side of the trans. This roll pin slides in the groove as you work the pedal. What happened was the coupling was pushed too far to the left and caused the pin to get out of time with the groove which would not let the coupling move back to the home position. All I would have had to do is jack the right rear tire of the tractor off of the ground, put the tractor in neturel, push the activation shaft in and rotate the RR tire a little and release the shaft. It probalby would take a couple tries but you would get it after a bit. This may not be very clear, but I thought I would explain it as best I could.
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[abritton77]

Well I was wrong about the coupling going so far that the roll pin overtraveled. The problem was a missing lock ring on the outside end of the diff lock shaft. The lock ring allows the collar surronding the shaft to push the shaft out. Without the ring, the collar will mve independently of the shaft. I can see how the locking ring can wear and fall off very easily. If you ever have this same problem, the rings only cost about a dollar and is very easy to fix. First you have to get the diff lock disengaged. To do this I think all you need to do is jack up both rear tires off of the ground with the tractor in neutrel and work the tires back and forth to get the locking coupling out of a bind and then pull the shaft out with a pair of pliers. I tore the whole back end of my tractor apart to figure this out. Once you get it out all you have to do is install the lock ring in the groove of the diff lock shaft while you push the collar in with a screwdriver. Its kind of a pain to do by yourself but thers not room for 2 people. I hope this helps somebody. Knowing this would have saved me many hours of work, but at least I learned allot about tractor rearends.

 

[manganos]

Thanks!