CAT D4H WON'T MOVE

Nige · Oct 9, 2020

Without a Serial Number it's hard to be specific, attached is the adjustment procedure for a wide variety of D4H II & III machines.
If your S/N is not included post back and I'll see if there is a separate procedure for it.
I assume that you may have already checked but can you see any slop in the linkages anywhere..?

john chamorro · Oct 9, 2020

I wish that worn linkages was it but their all surprisingly tight. The pdf is the correct one. I'd like to find out what the measurements for movement are if there's any listed.

Nige · Oct 9, 2020

There are no measurements listed for how far the bell crank is supposed to move. It's all done with the linkage adjustments. That's why it's so important not to have any free play in the ball joints.

I'd suggest the next move ought to be to make the tests as listed on Steps 6-12 of the parking brake adjustment procedure (don't touch the linkages to start with) and see what results you get. Pay particular note to Steps 10 & 11 that can indicate the possibility that the parking brake valve is leaking internally.

john chamorro · Oct 9, 2020

OK. Without knowing what the pressures really are, it's a shot in the dark. The linkages are tight. Maybe too tight. The forward/reverse arm was broken when the owner forced the shift lever to get the machine to move. The bell crank was free but the linkage ball joint was frozen with mouse or rat ****. It's possible that the linkage for the park brake is bent. I have loosened and lubricated all the joints. I did not pay attention to what was or wasn't frozen before hand. He had stated that when he moved it from the fire zone to where it's parked that it was very sluggish. I'm guessing the brakes never released.

Nige · Oct 9, 2020

john chamorro said:
It's possible that the linkage for the park brake is bent. I have loosened and lubricated all the joints. I did not pay attention to what was or wasn't frozen.

In that case maybe it might be logical to do the complete adjustment procedure for the park brake linkage even before you consider putting a pressure gauge on it. If something in the park brake linkage is bent then the measurements might well be off compared to the specification.

john chamorro · Oct 9, 2020

I'll wait until I can get the pressures run and back into the linkages if necessary. I'm getting tired of hanging upside down on this machine.

HATCHEQUIP · Oct 9, 2020

If you dont have a gauge try taking the linkage off the valve and move it by hand. See if it lets it travel.

john chamorro · Oct 9, 2020

Yup, moves no problem. It seems though that the distance has a direct relationship to the pressures.

HATCHEQUIP · Oct 9, 2020

Just to be sure valve arm moves or the tractor moves

john chamorro · Oct 9, 2020

Valve arm moves and tractor will drive through the brakes in 1st gear. Steering clutches respond as they should. With machine up off the ground, either track will hard stop instantly if one or both frictions are pulled.

HATCHEQUIP · Oct 9, 2020

Time to start taking pressure reading like Nige has posted for you . On a side note Nige referring to steps 10 and 11 have you ever seen the orings between the steering housing and the frame blow to the inside and dump the pressure but not show a sign of a leak externally.

Nige · Oct 9, 2020

john chamorro said:
Yup, moves no problem. It seems though that the distance has a direct relationship to the pressures.

I wouldn't be 100% sure about that. The lever moves a poppet valve and so long as that valve seat the brakes should release. There is also a spring inside the assembly and from what I see it's the spring that closes the poppet valve as the result of lever movement. See below.

When the operator engages the parking brake lever, linkage turns shaft (1). Lever (2) is connected to shaft (1) and pushes poppet valve (3) down against check valve (4). This blocks the flow of oil from passage (5) to passage (11), chamber (17) and the brakes. This also opens passage (11), chamber (17) and the brakes to drain through passage (9). With no oil pressure to the brakes, they engage to prevent movement of the tractor.

I've also included the parts manual illustration for the parking brake valve because it's clearer than the illustration above. Note that the Rod 11 does not push directly on poppet 14, it pushes it via spring 13. Therefore what actuates the poppet valve 14 is pressure (via the spring) and not movement per se. If the external operating lever moves no further from the OFF to the ON position with the linkage connected or disconnected I would suggest that there may be internal problems in the park brake valve. Remove seat 16 and check for a broken spring maybe..?

john chamorro · Oct 9, 2020

It's unbelievable how complicated they have made the system. There's nothing worse than an engineer that has to justify his job. They design things to work and not to be able to simply diagnose a problem with a needlessly over complicated system.

Welder Dave · Oct 9, 2020

Be glad it's not a new machine that's all electronic with DPF. You have to pay someone big bucks to come out with a lap top just to diagnose the problem.

john chamorro · Oct 12, 2020

I went back in yesterday and disconnected the linkage from the control handle to operate the bell crank unobstructed. my thought was to feel if there might be a deten somewhere in the poppet valve system. The lever moves up and down freely and made no difference to position with the tractor warmed up and running. It has GOT to be in the internals of the brake release valve. I HAVE GOT TO GET A MANUAL!!!

Nige · Oct 12, 2020

The Service Manual for that tractor is two separate documents.
SENR5290 covers Disassembly & Assembly
SENR3115 covers Specifications, Schematics, System Operation, and Testing & Adjusting.

john chamorro · Oct 12, 2020

It looks like the 3115 would be the one to get. Thanks.

john chamorro · Oct 17, 2020

Thanks for all the tips, info and suggestions. After reading through a couple of different threads, I went back to a linkage issue. I pulled the floor pan and removed 2-3 tons of debris and rat "left overs". Some of the linkages were stiff and stuck. I got them all freed up and readjusted the main pedal to trans linkage and sure enough the brakes release. I don't know how long they had been stuck or dragging but they don't work worth a damn. I guess next is to research replacing the brakes. It's pretty tough working on a machine with no book and without knowing it's previous history. one thing for sure is that at sometime in it's life, somebody took it swimming. There's surface rust where you wouldn't expect it.

Nige · Oct 17, 2020

Well, well. A linkage problem at the end of the day. Who’d have thunk it.?

Nige · Oct 17, 2020

john chamorro said:
It looks like the 3115 would be the one to get. Thanks.

Here's one. Bear in mind that a new paper one is over $1,000, even in CD it's $600.
https://www.ebay.com/p/1332531290

CAT D4H WON'T MOVE

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