For some time I've been trying to cure the steering clutch problem on my D6c10k and so far I'm baffled. Thought I'd post the symptoms and what I've done so far and see if anyone can come up with an answer. (some of this has been posted a while back on the ACME forum for those who read it too) Here's my original problem: * The steering clutches don't seem to fully release and it take quit a bit of brake pressure to get it to turn...enough that it pulls the engine down a bit during turns. * If you pull both clutch levers back and drop it in gear it takes off just about the same as if you didn't have the clutch levers pulled back. * Trans pressure at the filter is about 350 psi cold (thought I had more but had a gage that read high) * pressure at the oil lines leading to the steering cluthces is same as filter at about 350 psi (cold) * When warmed up it is acts about the same (if I was getting pressure drop I'd expect it to get worse) What I've done so far: With that much pressure at the clutches I figured something must be hanging them up so I pulled the steering clutchs and found: * clutch plates are near new thickness and aren't warped * splines in brake drum are smooth so no hangup there * brakes look good I first pulled one clutch, and with the clutch piston blocked, I applied air pressure to the oil port. Seemed to get a lot of leakage at the seal at the back of the clutch flange. Thought....ok there's the problem. I pulled the clutch flanges and replaced all the seals...all the seal surfaces looked ok. To be sure I took the parts to the local shop and they couldn't see and wear problems. (I did end up pulling the bevel gear shaft and replaced the bearings...they weren't real bad, but since I was there I figured it was the time to do it.) Pressed the flanges back on to 25 tons... the spec. for measurement from the flange to the end of spline shaft is .125 ± .030....mine is at, or just above the top limit of the spec (around .165) but I don't expect .010" will cause a problem. Put the clutches, brakes, etc. all back together enough so I could test it and I'm still getting about the same pressure readings at the steering clutch oil tubes. I tried pulling back the clutch levers and dropping it in gear and it still tries to take off. It's still in the shop and doesn't have the seat on yet so I haven't done more than go back and forth a couple of feet. I'll probably go ahead and assemble the rest so I can take it out and get it warmed up and test it out some more. I even rigged up a way to measure the pressure required to release the assembled clutch to be sure the springs weren't too heavy, but they came in a little below the standard spec. (not suprised that used springs would be a little lighter than new spec.) Anyone out there run across a problem like this? What I can't figure is if I've got plenty of pressure to the clutch why isn't it releasing?? I'm hoping someone out there will come up with the obvious solution that so far I've overlooked. :Banghead
OK I'll bite. My question; I know you have 350 psi going to the clutches, right? Whats the spec? is it 350 + or - 30 psi? Maybe try bumping it up to the max. After you did all the work did you try turning to see if it was better? I'm not sure if pulling both levers back and putting it in gear is the best test. I understand your logic, but I don't really think Cat engineered them to do that. Maybe nothing is wrong? I know I've chased my tail for days at a time trying to fix something that wasn't broken. Let us know how it turns out.
bolt, The pressure spec. it 350 psi...Cat mechanic told me they start to give problems if it get down to about 285. I finally had a chance to try it out....it does seem to steer better now. It takes much less brake pressure and doesn't pull on the engine nearly as much to make a turn. (before you had to really stand on the brakes) I think you're right that pulling the cluthes back isn't a very good test, especially on hard ground where it rolls pretty easy. The clutches are bound to have quite a bit of oil drag as big as they are and with the number of plates. I'm hoping all is ok now...the clutch piston seals must have been leaking just enough to cause the problem without looking bad when took it apart. (I hate when you take something apart and can't see an obvious problem) Maybe now I can get to use the dozer a bit. I'm just an amature, but there are plenty of things to work on around the farm....brush clearing, fence dozing, waterways, and if I learn enough, some day terraces or ponds.
Well, you may have already done more work than you needed too. Many Cat dozers are susceptible to steering clutch & brake LINKAGE dimension and adjustment problems. This can be anything from worn out ball joints to worn or otherwise damaged bushings. Also bent control rods, even things like oil cans, rags, newspapers, porn mags, pop bottles, beer cans, well, you get my drift. Anything that can effect the proper movement of a control for steering or braking. Now, what you have to do, is carefully measure each piece of linkage and make sure that it is adjusted right so that it moves the EXACT dimension called for in the service manual. If it says 13.259 inches, that's what you have to set it to. You have to visually and physically check each part of the linkage from the hand control lever to the foot brake lever and everything in between to the control valve. You may also have to check the linkage inside the steering clutch and brake compartments for the same problems. As you know, you can spend a lot of money chasing problems in this area, but, as I say, often it is not a pressure problem at all. As for oil, where you are, SAE 10 or 30wt. TOTD oil is fine, or you could use a 15W40 product. None of them should cause much drag, unless it gets below 20 to 25 degrees F. Pulling back both clutch levers should completely release the steering clutches while the trans is in gear. I've done that a zillion times. It's a good test for linkage that is out of adjustment or blocked by trash or debris. That's what is leading me to suspect this may be the problem in your case from your description. I forgot to mention that some of these older Cats required removing a deck plate and greasing the zerks on the rods and bushings on a scheduled basis. Most folks don't even know they are there. If a bushing get bound up by lack of grease, that can help cause this type of problem too. Oh, by the way, using just air to check the pistons on these machines does not give a good result. But if you throw in a pint of 30wt. first, then blow some air, it's a bit better as a test. Cat piston seals need oil, lots of oil, to seal properly and work correctly. Your mention of worn or fatigued springs is also worthy of mention. Generally speaking, worn springs would cause a slipping problem, as if they are not -- again -- moving the parts required the proper dimension, the damn thing just won't work right. D6C's were, in my opinion, a better machine than the D6D that replaced them. I hope this helps you a bit in your quest. Good Luck!
I've gone through all the adjustments on brake and clutch linkages. Brakes: set band adj. 9 clicks from tight and adj pedal-to-seat frame distance to spec. Clutch: adj. linkage for slight free travel before it engages valve and adj. stops so that they hit slightly before valve spool bottoms out. I lubed all linkages and there isn't any debris blocking them since it was cleaned before doing the clutch removal) Trans oil is TDTO 30 as reccomended. I suppose what I could do is find another D6c and run it a little for comparison or have someone who has one run mine...the only one I know of close by is at the couty land fill. I really don't think it's working too bad...much better than before so I'm going to work it a bit and see how it performs
Enjoy your dozin'! And keep those darn porn mags out of your linkages!
I spoke to an operator today who used to run D6c's and he also thought that there shouldn't be any clutch drag with the steering clutches pulled back. Now I'm beginning to think that I should try adjusting the pressure up a little and see if it make a difference. When I talked with the local Cat shop they didn't think running up to 400 psi would hurt anything. I'll have to look through the book and see how the adjustment is made....(changing shims in a pressure relief valve if I remember right)
D6c I have a D6C 10K and I will try your test of pulling both steering levers at the same time to see what it will do. I have never done this before. The machine that I have does not take very much brake pedal pressure to make a turn but when I adjust the brakes I do it with the machine hot and I back them off by 5 clicks.
Dieselfixer, I ran my D6 a little more last weekend...pushed out a few trees in a fence row....when cold the clutches were dragging and would still pull some when both clutches were pulled back. After it was warmed up it steered much easier and would stop when both clutches were pulled. I'm guessing mine isn't the only one doing this...30 wt. oil on all those clutch plates has to create some drag.
My D6C will stop when both clutches are pulled in, but it takes a few feet. Also, it takes very little pressure on the brakes to make a turn. Gettin ready to do some work on mine right now, hoping to get the system charging again, had to stick the batteries on the charger the last few times. Rebuilt generator and a new regulator, should have it up and running tomorrow!
I have ran a couple of D6Cs and thought that they steered very easy with little or no drag on the clutches. I used to have an AD 12 Fiat and this was very hard to steer. Generally it was the seals on the pistons in the clutches that caused the problem. I eventually got some Viton seals in them and things got a lot better. Anyway I hope you got on top of its problem now D6c10k. Cheers.