JD 200C LC not traveling straight

[d9gdon]

This just happened all of a sudden.

When you push both travel levers, it steers to the left. You have to push the right lever more than the left to make it travel straight.

My first thought was a bad final drive, but it doesn't seem weak. What else should I start with?

 

[willie59]

Does it do this in both fwd and rev?

 

[d9gdon]

Yes it does it in both forward and reverse.

 

[d9gdon]

Dealer was out today. The pressure control sensor was out on one of the pumps to the final drive.

 

[willie59]

Good to hear you got it sorted out.

 

[d9gdon]

That didn't fix it after all. I just got back to the job site yesterday and found that out.

The dealer changed the sensor, swapped the coils out on the two pumps to rule it out, took the spool apart and looked at it, and now they're saying the pump for that final is bad? When I was there the first time, the tech said the pump wasn't getting the signal to stroke the pump and that was the reason for changing the sensor.

I don't see how the tech went from low voltage to a bad pump? Anybody got a suggestion for me to try while I'm there?

 

[ddigger]

I would look at the rotator manifold, bad seals in there would cause that problem. Relitive easy and cheap fix if no hard parts are worn.

 

[Scrapper]

If the pump was bad wouldn't other functions that use that side of the pump be acting up also?

Is there any difference if you select fast or slow for the travel speed?

You could try swapping your lines on the center joint to see if the problem goes from one side to the other. That would tell you if the problem is in the final drive motors or not.

 

[willie59]

As Scrapper noted, if one of the two pumps were bad, you would notice lack of power/performance of some of the boom/digger functions as the two pumps provide power to the digger as well. If excavator part of machine is working proper, that tech is out of his mind (or lacking one) to suggest your weak drive problem is caused by failed hyd pump.

 

[ddigger]

Center joint=rotator manifold

 

[Scrapper]

Center joint=rotator manifold

Yes they are both the same.


You could also have oil by-passing in the center joint (rotator manifold) that could cause one side to travel slower than the other side.

Swapping the lines on the top side of the joint (near the swing motor) should tell you if your problem is in the upper part of the excavator in one of the valves or in the lower undercarriage part of the machine either in the final drive or the center joint.

If you swap the lines and the problem doesn't move from one side to the other than you problem is either in the drive motor or the center joint. If the problem switches sides than the problem is in the valving somewhere on the machine.

 

[Extractorfan]

We had a similar problem on a JCB 13 tonne excavator, one side tracking slow also the bucket crowd was slow. Swapped the two pump outputs over & the opposite track & dipper slow, turned out to be spool end on the pump swash plate worn, could'nt get parts so had to have new pump. Hope this helps.

 

[d9gdon]

Center joint = rotator manifold = mass confusion. You wanna try that in English please? Me no savvy. I know you're telling me something simple.

I don't like excavators and haven't worked on them too much.

I went by there today and found out if you travel with both travel sticks forward and the left control stick slightly pulled in (which would be the swing function) that it will work correctly.

The other functions all work great: boom, stick, curl, and swing.

 

[sultan]

Center joint = rotator manifold = mass confusion. You wanna try that in English please? Me no savvy. I know you're telling me something simple.

I don't like excavators and haven't worked on them too much.

I went by there today and found out if you travel with both travel sticks forward and the left control stick slightly pulled in (which would be the swing function) that it will work correctly.

The other functions all work great: boom, stick, curl, and swing.

They're talking about the centre swivel joint located in the middle of the excavator. You'll see a bunch of hoses going into it on the upper half of the machine, and there are hoses coming out of it on the bottom half (undercarriage) of the machine (you won't see them from above as they're under the machine). These hoses are what power the track motors. It's what carries hydraulic oil from the body of the machine to the undercarriage and allows the excavator to spin continuously without hoses getting tangled up.

One possible cause of the issue you are facing are leaking seals within this centre swivel/centre joint/rotating manifold/whatever-you-call-it. This can cause hydraulic flow to leak from one track's side the other. A good way to check if this is the cause is to switch the hoses for the two sides of the undercarriage at this centre joint. If the machine continues to turn in the same direction when tracking as before the switch, the problem is in the centre joint. If the machine starts turning in the opposite direction after switching the hoses, that means that the problem is upstream (such as in the pumps or valves).

 

[d9gdon]

Thanks, I see what you're saying now. It sure makes sense how that would cause the problem.

I'll have to look at it and get back here with how it went. As always, I appreciate all the help.

 

[cutting edge]

Check track tension on the slow side, ill bet its singing tight.

A bypassing rotary would give you low power more than low speed.

Have a QUALIFIED tech check cycle times,PVC codes and pump regulator operation and adjustments.Also check the travel motor case drains on both motors.

Its least likely a pump gone south.

 

[d9gdon]

No, the track is not too tight on that side and it does feel like it has low power on that side. Even though it's slower track speed than the other side, it seems like it loses power going up a small incline.

Like I say, the other functions all seem normal to me and the tech. He did mention the pump regulator might be it, but then decided against it. I can't say for sure if he checked it later or not, but he was out to the site twice after the first visit. He mentioned the wiring harness too since he was getting a low or no voltage reading at the sensor after hooking up to the computer. Don't know where he went from there.

That case drain could be something to rule out.

 

[mw85]

It sounds like the service tech has no clue. Call the dealer ship and tell them to have a different tech come out. I would check case drain on that travel motor. If case drain was correct, then check the swivel joint. You can take the swivel joint apart and reseal it your self. If the seals are good, then check case drain on the pump. But you said all the other functions are ok. So the pump should be good.

 

[ben46a]

Likely the swivel, I rebuilt two from a 375 cat one time and the only seal left was the one sealing the oil from the outside, the other 4 were completely gone. No idea how it even moved let alone steered.

 

[d9gdon]

Yeah, they're pretty frustrated with the current tech.

I'm going by there in the morning to find out more and see what I can do. It doesn't have them locked down, just aggravating.