D4H LGP - tranny engages but does not move

[N00bie]

Powershift transmission

Original issue: Transmission would not engage when transmission fluid warmed up (180-190F).
Added fluid changed transmission fluid, no effect. Suspected Transmission charge pump. While
waiting for pump and other things, ran dozer until tranmsission rose to about 170F but before
began slipping and/or not wabnting to engage.
Parked dozer. Next day came back to move it to the garage to put in nrew charge pump. Would not
move. Could hear going into gear, drive shaft would stop turning, and dozer would not move. Put
in new charge pump, made no difference. Increasing idle causes motor to load (black smoke). Drive
shaft (in forward) does try to creep a little.

Current pressures:
Drive Shaft: Spins freely in neutral, stops spinning in gear (F or R)
Transmisison Charge Pump: 50-75 psi in neutral, 0 psi engaged
Rear ports:
Lower port (rt side): 0 psi at idle, 300 psi gear engaged
High port (lt side): 250 psi at idle, 350 psi gear engaged

Any new thoughts?

 

[DMiller]

Drive shaft stopped turning, no real slippage sounds like something is bound up, brake(s), linkage for brake(s) a parking control that is not disengaging or a final that has finalized. There is something amiss AFTER the hydraulic system. Try putting in gear low throttle and making it turn If you have room, to either side to see if any movement, if none start digging into the brake system.

 

[N00bie]

"Try putting in gear low throttle and making it turn If you have room"
I have room but the drives shaft does not turn so cannot make a turn, Have tried playing with the brake handles but nothing. At high throttle, in first gear, the drive shaft and tracks try to move, i.e., they move very slowly. But engine under strain and have only done this once or twice for very short period.
I am not a mechanic but do have a assembly/dissasembly manual.

 

[DMiller]

You should really drop the coin to get a technician to look at it. Could save you literally hundreds in repair costs not chasing phantoms as could be something more simple or well expansive above your abilities. While you are trying to work it to figure it out may damage something else in process, so let a tech at it next chance you can call one.

 

[N00bie]

I agree with you but not so easy around here. The nearest CAT dealer is 2-1/2 hours away and IF they come, they charge you per hour from the time they leave the office. Hence, you have a 5 hr charge even before they arrive. I called a few local people that work on dozers in the area, but none have time to take a look at it.

 

[koecon]

Recheck your pressures in gear, brake pedal released, pull 1 lever half way back to block oil to that steering clutch. Note: the machine might move! Then pull all the way back to block oil to that brake.
Next do the same with the other lever! A change in trans pressure of more then about 20 psi indicates excessive leakage in that clutch or brake.

 

[N00bie]

Being a dumba--, which port do I put the pressure guage. I opnly have 1 but think need to order a couple more.
I assume you are talking about the ports in the back of the machine (transmission) but which one?
Bite the big one and ordered service manual.

 

[koecon]

Start with the high (left) port which is called P1.

 

[N00bie]

Will try to run the pressure tests in a day or 2 as it will take 2 people and the only one around to help me is away for a couple of days. Will do the pressure tests when he is available and get back to you.

A local guy that works on dozers told me to pull the outer axles and see if the driveshaft rotates. That will isolate the issue to the brakes or drive. What you think about that?

Let me also add something I had completely forgotten about.

The brake handles, one of them (the lft) springs back all the way, feels like it is spring driven.
The right does not and is loose in like the mid position, but otherwise operates just fine (broken spring?).
I had noticed that sometimes when applying the left brake to turn, the dozer really slows down and the engine starts to bog down (yes, with black smoke). Pushing the rt handle all the way forward and the lft brake works perfect.
My thoughts were they were binding with each other or something.
Was going to open up the side panel to see what the linkage was doing, but other problems were a priority.
Could this be related? More evidence a brake issue?
Thanx

 

[koecon]

Yes, the lever not returning could be at least part of the problem!

 

[N00bie]

koecon,
YOU ARE ON THE RIGHT TRACK !!!

Start engine.
Engage gear.
Play with brake/steering levers.
Dozer moves !!!!
By moiving levers to half position, lft/rt, I was able to move dozer about 30 yards forward and about 20 yards backwards.
Engine working hard so didn't push it hard.

Seems to me that the brakes are locked????

 

[N00bie]

BTW. The parking break rod seems to have been broken long ago. Maybe bouncing on the rocks has moved the plunger/valve ?? Going to check that out now

 

[koecon]

Yes check that but I'm still concerned about high oil leakage in a clutch or brake.
You do need another gauge because the trans pump pressure can not be less than the P1 pressure! Maybe an intermittent problem also.

 

[N00bie]

Going to run pressure tests tomorrow. But here are some more interesting facts.
As I said, the parking brake rod has been broken long ago and the linage is completely frozen. However, the rod that heads down to wherever is free (this I assume is what actually sets the parking brake). I can manualy (with a bar) move it up and down. But, whether up or down, seems to make no difference.
Screwing around with the levers and stuff, the dozer now moves forward, not happily but it moves. Interestingly it moves in a straight path. Brake does not work anymore! When I step opn the brake, it could care less and continues in its straight path.
Again, although moving at high trittle, it is not happy (black smoke).
Whatever is holding it back, seems to be uniform, i.e., affecting both sides equally.

 

[koecon]

Sounds like the brakes are pretty much fully applied and you are driving through them.
In first gear you should be able to do that but not in second and third.

 

[N00bie]

In first gear you should be able to do that but not in second and third

Correct, only in first gear. Struggles in reverse.

 

[N00bie]

You do need another gauge because the trans pump pressure can not be less than the P1 pressure

From above, the pump pressure (at filter) is about 75psi at idle.
P1 is about 300 psi at idle.

Will do more testing tomorrow afternoon.

How do I release the brakes is the big question...

 

[koecon]

By memory that's not possible! I might need to look at a schematic to varify.

 

[Junkyard]

Does machine relax once you shut it off and pull on levers? If so you've got good brakes and sufficient pressure.

Sure sounds like a linkage issue. Fixed many a machine that was simply bound up. I'm not intimately familiar with this machine like I am a D11 but they function similar. Pull the floor out of it or whatever you need to get to where the linkage goes from the levers to the control valve. The lever that you flip down to lock out the left and right levers also applies the brake. It may be bound up and stuck on. Get all that free and working correctly before you mess with anything else.

I've seen some with linkage so worn and stiff we added bungies to it as a return to help release brake when safety lever was flipped up to operate.

If machine pulls good on both sides when working you shouldn't have a steering clutch seal leaking or excessive wear. If it pulls good on one side and not the other then I'd be more inclined to think you have a bad seal or worn out parts. Kind of repeating where you're headed but I've seen it before and been told it had to be internal only to have fixed it without even hooking a gauge up.

FYI the test fittings should be male PD. On big machines there are four, one each side brake and one each side steering clutch. Should see around 300 give or take 15-20 if it's anything like the 11.

 

[koecon]

Those pressures are possible because the filter only supplies lubrication oil. Have you inspected the pump suction screen and filter for debris from a component failure?