John Deere 850C Tram Problems

[jlittle2212]

When you tram the dozer, you have to hold the controller almost all the way over to the left to get it to tram straight. If you are in a push, its not as noticeable. If you leave the controller in the straight position, it will tram to the right.

Any help would be great! I will answer any questions best I can.

 

[Deereman]

Sounds like one of the speed sensors is off?

 

[jlittle2212]

Sounds like one of the speed sensors is off?

Need calibration you think? Where are they located on these machines?

 

[Deereman]

One on each side drive motor. Yes sounds like it needs to be

 

[Deere tech]

You can disconnect both speed sensors and if the machine travels straight then the problem is most definetely the speed sensor. If it is mistracking to the right then the left speed sensor is the problem. The TCU isn't seeing rotation on the left motor so it tries to send more oil to it to get it to spin as fast as the right.

 

[jlittle2212]

You can disconnect both speed sensors and if the machine travels straight then the problem is most definetely the speed sensor. If it is mistracking to the right then the left speed sensor is the problem. The TCU isn't seeing rotation on the left motor so it tries to send more oil to it to get it to spin as fast as the right.

If speed sensor is the problem, will it damage the machine anymore to run it until I can get them replaced? What do the speed sensors on the pump control?

Also, it seems to "free up" and run fine after a "pop" occurs on the stuck side. The only time you need to free it up again is if you turn the key off.

 

[Deere tech]

If the problem is a speed sensor then you shouldn't damage anything by continuing to run. However your problem doesn't sound like a speed sensor issue. The speed sensors tell the TCU how fast each track is moving so the TCU can make minor adjustments to the travel pumps to keep the machine going straight.

It is concerning to here that things free up after a pop noise is heard. that is indicating that you have a mechanical issue going on and will most likely get worse quickly if it is not repaired. The complaints you have lead me to think that there maybe something hanging up in the p-brake on the bad side. To test that theory if you apply the p-brake with the machine running then release it and the travel 'resets' itself like you just turned the machine off then the problem most likely is in the park brake.

 

[jlittle2212]

when you pull the parking lever down to move machine, it will not move until you reach down and pull the pedal up another inch or half inch. Then it will move.

I will check disengaging the handle with machine running to see how it reacts tomorrow.

Is there a relief on the park system that could be sticking and then frees up under higher pressure causing the pop then travel?

 

[Deere tech]

The brake pedal sticking down a little bit is pretty normal when the brake linkage starts to stick a little bit. Its shouldn't be causing any issues. There are two park brake assemblies on the machine, one on the right motor and one on the left motor and they are released at the same time with the same oil line so if a relief was causing the issue it would affect both of them.

 

[jlittle2212]

The brake pedal sticking down a little bit is pretty normal when the brake linkage starts to stick a little bit. Its shouldn't be causing any issues. There are two park brake assemblies on the machine, one on the right motor and one on the left motor and they are released at the same time with the same oil line so if a relief was causing the issue it would affect both of them.

If you press the brake, it only works on one side. Probably a totally different issue.

If you disengage the handle, everything still works like it should after engaging it. It only appears to get stuck when you turn the key off and restart the machine.

 

[Deere tech]

Well I cant imagine what could be causing it. It doesn't sound like a brake issue, maybe something w/ the travel pump. I cant explain the popping noise. It sounds like you just need to not shut it off and your problems will be solved..

 

[jlittle2212]

Well I cant imagine what could be causing it. It doesn't sound like a brake issue, maybe something w/ the travel pump. I cant explain the popping noise. It sounds like you just need to not shut it off and your problems will be solved..

LOL.

You got that right. It hasn't got any worse and has been that way for a while. I guess it will show its self.

 

[Mjrdude1]

It would be money well spent to pull a couple oil samples on the hydraulic system and the final drive on the affected side. Hydrostats are huge dollars if allowed to shell out.

 

[jlittle2212]

It would be money well spent to pull a couple oil samples on the hydraulic system and the final drive on the affected side. Hydrostats are huge dollars if allowed to shell out.

You got that right.

Done another test today. Propped up machine to run, when going forward, without steering left or right, the right track has normal speed, the left track will barley move throttled all the way up. In reverse, both tracks will tram, but the right track seems to be a little faster.

Help anyone?

 

[Deere tech]

The Deere dealer should be able to connect to the machine and read codes and values for the sensors and joystick and do pressure checks if necessary...

 

[jlittle2212]

Bad PCP on the pump was the problem!

 

[xxwestroxx]

Bad PCP on the pump was the problem!

What is PCP? And where? Thanks

 

[xxwestroxx]

Found them.