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hello sir... i have a D6H SERIES 2 DOZER which loses speed…

hello sir... i have a...
hello sir... i have a D6H SERIES 2 DOZER which loses speed as if the brakes are not being release, its fried my transmission and converter, i can't seem to get a decent mechanic to locate the issue. please help me out.
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Answered in 6 minutes by:
11/3/2013
Mechanic: catmastertech, Technician replied 9 years ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,036
Experience: Field service technician for CAT 19 years.
Verified

Welcome to JustAnswer. I am online most nights and weekends a few hours.(US-Eastern)Please do not rate my answer until you are completely satisfied.

 

Have you checked the steering and brake hubs?

I have seen a similar pressure problem were the hub seals in the steering and brake clutches wear worn out and leakage was preventing the proper pressure in the brake release and steering apply pressures. I believe lube oil pressure was higher than normal also.

 

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Customer reply replied 9 years ago

what do you mean by the break hubs? as if leakage around the outside of the final drive?

Mechanic: catmastertech, Technician replied 9 years ago
Please remember to post the serial number of your equipment. This helps me find the correct information to assist you, Donnie.
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Customer reply replied 9 years ago

the serial number is XXXXX

Mechanic: catmastertech, Technician replied 9 years ago

The actual name is XXXXX XXXXX the parts book. Item #24 has seals that cause the problem on a D6H I repaired years ago. Item #44.

 

Sorry for the repeated images, site would not take it correctly.

 

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Customer reply replied 9 years ago

np.. based on what i can get from the SIS diagram.. this seal is on the outside of the final drives correct? not where the clutches and disk are?

Mechanic: catmastertech, Technician replied 9 years ago

three seal rings (28) from the hub assembly

 

 

 

 

These are inside the steering and brake clutch assembly, behind the final drives in were the drives connect to the transmission.

The final drive would be removed leaving the small bolts installed and removing the steer/brake group with the final drive.

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Customer reply replied 9 years ago

so you are saying that my problem lies inside the final drive and not the control valve? I am curious in determining which one of the final drives have that seal damage. the pressure taps on the control valve indicate as says the book that the left final drive has that issue. the valve under the seat has the 4 adjustable knobs facing west. the right pressure tabs control the left side and the left pressure taps control the right side, as shown in the repair manuel. I do have leakage coming from the right final drive if you are sitting in the seat.

Mechanic: catmastertech, Technician replied 9 years ago
External leakage has nothing to do with this problem.
Valves are normally arranged with the layout of the machine. (ports on left side are for ports on left clutch/brake)(always viewed from operators seat) I not clear about how yours is arranged, maybe I am misunderstanding your post.
The steer clutch/brake assemble is not considered part of the final drive group. No pressure oil is sent to the final drive. It does remove as an assembly with the final drive to make it easier to balance and handle.
If lube pressure is higher than normal and steering or brake pressure is lower then normal, that is the side to start on. I would recommend both sides be repaired unless you know the other side has been repaired earlier.
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Customer reply replied 9 years ago

understood. So my issue where the machine slows down to the point where it cannot even move and has to be cooled for 1-2hrs before it can move again is not from the control valve but the steering and break assemble.. i will try and swap them out tomorrow and let you know what i get. i have 2 replacement sets available.. what time is best to reach you? I am reaching you from ghana, west africa.. our time zones are a bit different.

Mechanic: catmastertech, Technician replied 9 years ago
If you are loosing brake pressure, (remember brakes are spring applied and oil pressure releases the spring) then you would be correct when saying the brakes are applying while operating.
The technician I was helping on this machine had gone through the valve and everything else on this tractor as you have. That is when we felt the only thing left was the steering clutch hubs. When they were remove, deep grooves were found were the seals contact the housings. The hubs and housings were both replaced to correct the problem. I am not sure any REMAN parts are available for the D6H machine, at that time , none were.

All contact is strictly limited to this site. I am only line most nights to about midnight US Eastern time.
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,036
Experience: Field service technician for CAT 19 years.
Verified
catmastertech and 87 other Construction and Road Equipment Specialists are ready to help you
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Customer reply replied 9 years ago

thank you will let you know asap.

Mechanic: catmastertech, Technician replied 9 years ago
Thanks for the accept and bonus for my answer.
Please feel free to post to this same question about this problem. I will be glad to help as much as I can.
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Customer reply replied 9 years ago

Hey Mastertech srry for the delay feedback.. we pulled out the right brake and steering clutches only find them burned out.. the plate and clutches were all burned till only the metal was left on the the clutches. After reassembly, we could only achieve 250psi on the brakes... did all the adjustment on the control valve but could not go past 250psi.. could the rod adjustment also effect the pressure?

Mechanic: catmastertech, Technician replied 9 years ago

You are absolutely correct. I don't work on many of these older machines currently. I had forgotten the brake pedal adjustment. The pedal can stick or not return properly and cause dragging as well.

Here is the measurement of the linkage.

 

 

 

 

 

 

 

(1) Bolt. (2) Adjustment Bolt. (3) Locknut. (4) Spring. (5) Adjustment Bolt. (6) Locknut. (7) Locknut. (8) Rod end. (9) Pin. (10) Service brake pedal.

(1) Torque for bolt ... 120 ± 20 N·m (90 ± 15 lb ft)

(7) Torque for locknut ... 45 ± 7 N·m (33 ± 5 lb ft)

 

Procedure To Adjust Service Brake Pedal Linkage

1. Adjust spring (4) stretch to 3 ± 1 mm (.11 ± .04 in) with adjustment bolt (2) and secure in place with locknut (3).

2. With service brake pedal (10) against the upper stop and valve stem depressed, adjust rod end (8) to allow free fit of pin (9) in rod end and valve stem.

3. With service brake pedal (10) depressed and valve stem extended, adjust bolt (5) until it is in contact with service brake pedal.

4. Release service brake pedal and adjust bolt (5) out 1/2 turn and secure in place with locknut (6).

 

EARLIER models are different,

Torque for all 1/2 in. locknuts (jam nuts) that hold the rod ends in place on the rod ... 45 ± 7 N ± m (33 ± 5 lb ft)

NOTE: All rod assembly measurements must be made in a straight line between the centerlines of the rod end mounting holes.

(B) Assembled length of rod assembly ... 975.0 ± 1.5 mm (38.38 ± .06 in)

(C) Assembled length of rod assembly ... 386.0 ± 2.0 mm (15.20 ± .08 in)

(2) Torque for bolt ... 135 ± 15 N·m (100 ± 11 lb ft)

Procedure To Adjust Service Brake Pedal Linkage

1. Install adjusted rod assemblies (B) and (C).

2. Install pedal (3) so that the slot of the pedal is one spline tooth down (counterclockwise) from the timing mark on the shaft.

NOTE: To bring the pedal closer to the operator, the centerline of the slot of pedal (3) must be in alignment with the timing mark on the shaft.

3. Adjust the head of bolt (5) to dimension (X) 45 mm (1.8 in) from the support. Bolt (5) is the upper stop for the brake pedal.

4. Hold brake pedal against upper stop and push valve plunger all the way into valve (1). Then adjust rod end on rod assembly (C) so that the pin that connects rod end to valve plunger has a free fit.

5. Push brake pedal down until valve plunger stops.

6. Adjust bolt (4) until head contacts brake pedal.

7. Release brake pedal and turn bolt (4) an additional 1/2 turn out. Tighten locknut

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Customer reply replied 9 years ago

exactly as you said, after readjusting the brake pedal linkage, we were finally able to achieve the 400 psi as stated in the book. Should there be anything else we should look out for? I'd like to not go through this again, Ive spent thousands of dollars because of this and I've lost a lot of contracts and damaged a bit of reputation.

Mechanic: catmastertech, Technician replied 9 years ago

Sorry to hear about your customers confidence in you is down. They should remind themselves of the cost savings they are looking for when they contract with you. You cannot have all the latest information available unless you pay for it and this would ultimately drive yours and his cost up.

I believe you have been through everything in this unit. Nothing left to rebuild except, the convertor. The only issue left is to document all the pressures. Keep a record on file just in case he comes back and tells you it is not working right and he sent it somewhere else. Then you have proof you had the pressure correct and he should contact you before running off to some other shop.

I did not need to do this until the last few years. Friends do not exist in this world anymore. You must be in CYA mode all the time or someone is going to try and stick you with everything they can.

I wish you the best on this and hope things return to normal soon. If you need more help, please ask for me on you next question. Thanks, Donnie

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Customer reply replied 9 years ago

Donnie, one last issue... the machine seems ok but the latest issue I'm having is ruff shifting. when you change from forward to reverse or vice versa.. the machine stutters then shifts into the desired direction. you hear a loud kmpp noise. its like when you have a car sloped on a hill and you change the gear from parking to reverse.. that loud noise it makes before it shifts into it. I was looking at the service manuel and it was saying something about the load piston. could you elaborate on it or if something else we should look for? thank you.

Mechanic: catmastertech, Technician replied 9 years ago

Hello again, I thought you had this one behind you.

The problem sounds like trash is in the control valve orifices. The load piston is a cushion for directional shifting. The speed clutch will always lock up first, then the directional clutch should follow slightly slower. You should see this when pressure testing and have gauges on both ports while watching the shifting.

Don't confuse this with the load plug test. This is related but, not the same issue.

If the problem was more from wear, I would believe you would have more trouble with it sticking in neutral caused by a safety valve sticking or worn.

You may need to inspect the strainer and change the oil again plus use the high efficiency filters (clean-out). I would remove the valve assembly and check the valves and orifices.

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Customer reply replied 8 years ago

Hello, its been a while. Since the last time we spoke, I've rebuilt the steering and brake clutches of the machine. for some odd reason we can't seem to get the pressure on the left side of the machine from the steering and brake control valve. The right side and both break pressure's are appearing and correct. could there be leakage in the tube that distributes the oil to the clutches? Also is it best to examine the tubes by removing the transmission housing? I've had the machine parked for some time now. trying to get it up and going.

Mechanic: catmastertech, Technician replied 8 years ago

If you are certain the hub was not worn out or the seals could be damaged on that side, the next area would be to check the tubes. You should see inside the transmission from the rear cover well enough to know if the tube is cracked or loose in the frame.

If you do not see oil spraying from the tube, then check the control valve. It may have a sticking valve.

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Customer reply replied 8 years ago

I've replaced all the seals inside the steering and brake assembly. Ive also taken the control valve to a certified pump servicer where they disassembled everything and cleansed all the dirt inside the valve. I've also flushed out the oil and used the high efficiency filters as you suggested earlier. the idea.. I've thinking of using a portable tire pump and pass air through the holes through the tubes after removing the control valves. i get small pressure but the most I've received is 90psi, its as if the oil dumps somewhere and not enough is contained inside the control valve to maintain the pressure. I'm getting 335 on the right side and 410 on both left and right brakes. just the left steering I'm not getting past 90 and the gauge moves very slow to reach this.


 

Mechanic: catmastertech, Technician replied 8 years ago

That is why I wonder about the valve. Some pressure is like the lever is being pulled back to disengage the clutch. This would lower the pressure so the clutch would slip and the machine would turn instead of going straight.

Is the linkage binding? Could the lever be too tight, hold the clutch released?

Could the valve be assembled wrong?

Did you look at the tube with the rear cover off? If so, did you see anything?

 

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Customer reply replied 8 years ago

well as far as the linkage, removed all the linkage and checked the pressures without them and no i haven't looked at it with the cover off. but what i did was while the assembly was off.. i turned on the machine. high pressure oil came through the middle hole.. followed by the right side with the pressure a little less, then the left hole came after some delay but it was not too strong. I'm trying to understand how the valve reads the pressure and why the steering side is not reading the pressure but the brake side reads excellent.

Mechanic: catmastertech, Technician replied 8 years ago

The steering and brake valves are all separate valves. One valve is for each function.

 

Left steer, left brake, right brake and right steering. If your valve is sticking, it will only effect that one function.

 

The brake pedal does work both brakes but, it is a separate valve from the steering and brake control.

 

The lever for the left side does control both the steer and the brake for the left side but, it is controlling two valves.

 

Here is a guide to help adjust pressures in the steering valve. I hope this helps.

 

D6H steering test

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Customer reply replied 8 years ago

this guide is for the earlier models. mine uses the allen key adjustment. from what you are saying, would you recommend i buy a new valve? all 4 valves have been serviced also. the locker inside has been removed and it moves freely. We have removed all the levers on the control valve and still not getting adequate pressure on the left steering.

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catmastertech, Technician
Category: Construction and Road Equipment
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