help needed to adjust differential lock on a ford 335 industrial tractor

[ovrszd]

makes sense....here are the instructions on adjusting the linkage for the differential lock taken from the workshop manual, with questions I have in parenthesis (???) that I would appreciate comments on: question:

1. remove the cotter pin and clevis pin and disconnect the differential lock operating pedal.

2. depress the operating lever until the differential lock is fully engaged. (how do you know if it's fully engaged? how much travel should be expected, measured from the end of the operating lever?). If the gears are not meshed the operating lever will only move 1/2" or less. If they are meshed it will move an inch or more.

3. Loosen the locknut, then adjust the length of the operating rod and clevis assembly until the clevis pin can be inserted without compressing the spring in the operating rod. (what position should the pedal be in when making the measurement and connection - resting on the footrest, raised fully, or something else?) Pedal would be laying on the floorboard. So you are creating a situation where the locker is engaged, pedal is on the floor, pedal spring is NOT extended.

4. remove the clevis pin, then shorten the operating assembly by one turn. Re-insert the clevis pin retaining with a new cotter pin. This adjustment puts slight extension on the pedal spring.

5. Tighten the locknut to the correct torque.

6. Check that when the load is removed from the pedal and the rear wheels are free to rotate, the differential lock linkage disengages automatically and the pedal assembly returns to the raised position. The wheels should then rotate independently. (how can this be tested in the shop - have both wheels raised off the ground? also, what is it that has enough lift to raise the pedal after it disengages?). Jack up one rear tire. I'd suggest the right tire so it's right beside you while doing the adjustment. Rotating that tire or the inability to rotate it tells you whether the locker is engaged or disengaged. The internal spring on the locker lever is what raises or disengages the locker when there's no tension and this lever action pulls the pedal up off the floorboard.

any comments would be appreciated.

See my comments in red above.

 

[pabble]

great! answers my questions fully and clearly....very much appreciated!!
bryan

 

[pabble]

overszd.......I think I have the adjustment made correctly now, or at least close - when I have the wheel off the ground (as you suggested) and push the lever down manually it does engage and disengage as I move the lever. However, when all the linkage is attached and adjusted as recommended there doesn't appear to be enough force to lift the weight of the pedal and disengage (but can still lift it manually OK). In your comments above you reference the "internal spring on the locker lever" - do you mean the one used in the external pedal linkage or the other referred to previously, inside the axle housing? If inside the housing perhaps that has failed and as a result there isn't enough force to lift the pedal plus linkage, or does it suggest improper adjustment (maybe of the set screw)?

 

[Ultradog MN]

Your problem is not external. It is internal.

 

[pabble]

OK....thanks very much.
bryan

 

[ovrszd]

I was referring to the spring assembly that connects the pedal to the locker lever on the axle housing.

I'm with Ultradog on this one. Something seems to be wrong inside.

If the internal spring was broken wouldn't the weight of the lever and pedal assembly cause the diff lock to be in the locked position all the time??

 

[Ultradog MN]

If the internal spring was broken wouldn't the weight of the lever and pedal assembly cause the diff lock to be in the locked position all the time??

I agree.

 

[pabble]

In the short time I've had the tractor the lever was hard to move and wouldn't go down - but I soaked it in PB Blaster for a few days after removing the linkage and when I came back to it it would move freely, so wasn't engaged before I started trying to "fix" it. Now, with the lever in place but the linkage removed it has enough lift to say in the disengaged position (so will leave the linkage off until proper repairs can be made)....was wondering if I could just leave the linkage off and engage and disengage it by hand...would be easy enough to reach from the seat - would that work without causing problems, assuming I disengage it as soon as traction is restored and didn't try to turn?

 

[Ultradog MN]

My first tractor with diff lock was a 3000. (same as your 335) When I bought it it didn't have any linkage for it. Never had it from the factory. Except, the lever (part # 18 in the second link I posted above) on the trumpet was there. So I bought the linkage from a junk yard - (Parts #1 through #16) and had to pull the trumpet to replace pin #3 where the 3 point arm and diff lock pedal attach. I do remember experimenting with lever #18 before I bought the parts and with the right tire jacked up I would push the lever down and it would go down ONLY when I turned the tire and the cogs inside lined up. But it wasn't a two finger deal. It took good pressure with the heel of my hand to push #18 down and compress the big coil spring inside and engage it.
So getting to my point here; can you tell if the lever #18 is spring loaded? After freeing up the shaft with PB does it snap back to the up position? If it springs back smartly you should be good. But if it is limp, weak or stays down then you have a problem internally and as we've discussed, I'm thinking (hoping) it is the set screw.

 

[pabble]

ultradog, that description really helps about the force of the return when the lever is pushed down manually to engage, and the force noticed when the lever returns by itself to the disengaged position.....mine is easy to push down and does not spring back smartly - a limp, weak return describes it very well. it's sure looking like the problem is inside the axle housing - haven't done that type of repair work before but the instructions in the manual seem clear so may give it a try....thanks again...