Hi all I have a HD6E Allis Chalmers dozer with a steering problem. Maybe I should start from the beginning. My brother and I bought a HD6E that wouldn’t steer right or left. The dozer would roll well but when the brakes were applied they simply wouldn’t work. The steering clutches would also not disengage when pulled. This machine has a screen in the lower transmission housing that supplies oil for two pumps that operate the brakes and clutches. When I removed the screen I found that it was plugged with more brake lining material than what would be there for normal wear. I pulled the steering clutch covers and found a lining had come off and was laying in the housing getting chewed up by the rotation of the brake drum. I had the brake linings replaced (with rivets this time) and put everything back together. I started running the dozer pushing up a new pond dam and it seemed to work fine. Here is the new problem. After running the dozer for about an hour the left steering clutch and the right brake started to be slow to respond. In another ten minutes the right steering and left brake started to do the same thing. I can disengage the master clutch while pulling the steering clutch and applying the brake and I can “feel” the brake apply. Then the dozer will turn. There are a couple of things that I noticed that will make it turn better after this problem starts. If I get the dozer on a slope with the nose of the machine lower, the steering clutch will disengage and the brake will work also if I lower the throttle to about half they will also work better. Does anyone have any suggestions where I need to start looking to resolve this problem.
If it were me I would recheck the pump inlet screen again. It is pretty hard to get all of the material out of the system with one cleaning. Usually if it will work better at lower rpm it is an indication the pump is being starved.
yes and also the new brakes will wear quite a bit the first while till the seat on the drum also any gasket material on the top covers will be in there too
Thanks for the replies Bill and dirtdog. I’m sure everything was clean when I put it back together. I had to replace the bevel gear so I had all of that apart. The steering clutches were pulled along with the transmission. Everything was sprayed out with solvent and compressed air. I was pretty thorough because I knew that the screen could be a potential problem.
Not being familiar with the hydraulic circuit on the HD6, I would next check for a circuit relief. Also some machines have a inline filter to keep particles out of the valves that pass through the pump and screen.
Thanks Bill, There are two canister type filters one for each steering clutch/brake. They are after the pump and before the valve body. Both filters have been replaced. I even tried removing the filters from the cans to see if that would help. It made it worse. Less time for it to act up and harder to make the clutches/brakes work after the problem starts. I’ll check the service manual for a relief valve. Keep throwing ideas out there. Maybe you’ll come up with something I haven’t tried. Thanks, Joe
Oljoe have you check the springs in the valve body, after years of service they will get week. They are fine when cold but as the oil get hot the spring will get week . I have heard this to happen . Dave H
Here is an update. This weekend I ran the dozer for about 12 hours. It would be difficult to steer after about an hour. I read in the manual that there is a relief valve that is adjustable so I adjusted the valve, ran it for about 30 minutes at the end of the day and it worked fine. The next day I ran the dozer for about 45 minutes and the same old problem showed up again. Here's where it gets interesting. I shut down the engine for about a minute and started it back. The steering and brakes worked fine. Every time it started acting up I killed the engine for 30 seconds to a minute and it would steer again for awhile. What do you all think?
Oljoe have you check the suction line ,at the tank, it sounds like it is getting no oil or its getting air into the system. i will ask a older gentleman I know ,he has worked on heavy equipment all his life, he has forgot more than we will ever know. I will let you know what I find out. Dave H
I broke a track rail this weekend so I’m down for a while. I chained it back together and limped back to the shop. I guess I’ll drain the steering and transmission this week and take a look at the screen, suction lines and gaskets. I think I’ll replace all of the rubber hoses just to make sure none of them are leaking, clean the vents in the transmission and steering clutches and clean out the compartments again. I’m going to drop the belly pan to make it a little easer to get to the lines. Is there anything else that I should check while I’ve got this thing down? Dave, Did you get a chance to talk with the older gentleman?
oljoe I haven't track down the old gentle as of yet, is there a way you can test the pressure at the valve body, test when cold and when the machine get warmed up, it might be a week spring and when the oil get hot it let it bypass. If I find any thing more I will let you know Dave H
Here is the update. I got some help (from my brother who bought the dozer) to drop the belly pans. I finally got him to get dirty ha ha. I drained all of the oil. There was no metal on the magnets and the oil looked clean. Next I removed all of the steel suction lines and checked for leaks by plugging one end put air pressure in the other. There was a place on one line that had been braised but no leaks. I inspected the rubber hoses. They were a little soft but I didn’t see any evidence of any leakage. I got some new sections of rubber hose anyway just to be sure. Then I pulled the screen. It was plugged with very fine fiber material, probably brake lining. There was a small area along the bottom that was not completely plugged. In the screen compartment of the transmission there was more of the same material that plugging the screen. I cleaned everything up and put it back together using the new rubber hoses. I ran the dozer for 7 hours yesterday and the steering worked the whole time. I think what was happening was that the screen was partially plugged. When the pump was sucking oil the material floating in the oil would finish plugging the screen. When I stopped the engine the material would fall from the bottom of the screen and allow the oil to flow to the pump until it would plug up again. Thanks everyone for all of the suggestions and help.
Hi Oljoe Well I thick that is your problem solved, I have seen that before the brake lining dust is the worse thing . Good luck and keep in touch. Talk to you soon Dave H