My uncle is fixing up a friend's Komatsu D21E-6. The Serial Number is 61716 if that is needed. The dozer would not turn left and he figured out the left side driver clutch is stuck. So what would he need to do to be able to remove the clutch? Like would he have to remove the sprocket to do so? Or would he not have to remove the clutch to get it unstuck? Thanks for your time and a great day.
The sprocket does not have to come off. Access to the steering clutches is done from the top side of the rear of the machine. There are some good write ups on this forum from other variants of your machine. Many dry clutch dozers suffer this same trouble. Some folks have had luck with placing the dozer up against an “immovable” object such as a large rock or enormous tree and let the dozer push while keeping the control for the offending steering clutch in the disengaged position. If the rust is just light, it may break free. Just an idea before tearing into it.
With the left track elevated and clear of the ground, place a 2" round bar between the track chain and a sprocket tooth. With the left clutch handle pulled back slightly, (declutch, but don't apply service brake) and right handle fully pulled back applying service brake, gingerly apply the main drive clutch till the engine bogs or the stuck steering clutch breaks free. You may need to do this several times and go from forward to reverse action after repositioning your 2" shaft appropriately. No need to shock the driveline but it must be fairly well loaded to do this. The torque has a very good effect on breaking the frozen parts free. This photo fairly shows what I'm referencing:
Thank you both very much for the replies. Yesterday I went over to my uncle's place. We tried the method of having the dozer push to break the clutch free against a stump, but unfortunately it didn't break free and only thing that happened was the track digging itself in the ground. We also tried the method of elevating the track and placing a 2" shaft against the sprocket. Unfortunately that also did not break the clutch free. So it is looking like the dozer will have to be torn apart to fix the issue. Am I correct on that the top of the dozer (tanks, etc) is removed to gain access to the steering clutches? Also if it is possible, could you direct me to where those write ups on other variants of this machine are located? I'm not well versed in navigating forums like these. Thanks again for the assistance.
Here is one on a similar machine: Komatsu D21a-7 steering clutch Today I removed the covers over the steering clutches. After removing the brake band springs and all 16 of the flange bolts. the clutch assembly is loose and tries to come out but something is snagging as I try to lift the clutch assembly upwards. I'm missing something and the manual is very... HeavyEquipmentForums You tube video on the same type of job only older machine:
Is it hydraulic like the video above? If so it could be a fluid, filter, or brake adjustment issue
Apologies for not replying sooner, was busy with other things. We got it taken apart. The "fork", I believe it is called, was seized up; so we had to use penetrating oil and wedges to slowly move the "fork" to be able to remove the brake band/drum and clutch. Took some pictures when I was over there, apologies I'm not good at taking pictures. Does anyone what thickness the clutch plates are supposed to be? We miked the clutch plates and they all came out around .235. Spoiler: Brake band picture Spoiler: Brake drum picture Spoiler: Clutch picture Thank you for linking this video it helped quite a bit. Yes it is like video, just some minor differences from what I can tell, though I am still learning/new. Hopefully it is not an issue with the hydraulics, but I guess time will tell. Thank you for the reply. Thanks again for your time and have a great day.
I believe the clutch plates are 6mm when new. The steels should be 2mm. Sounds like yours are just like new.
Haha of course they are. Owner of the dozer has already ordered new ones, which are arriving Monday or Wednesday. Oh well, at least he won't have to worry about those for quite a while. Thank you for the reply.
Alright got most of the parts so we have started putting the dozer back together. Does anyone know know what the correct adjustment of the adjustment bolt of the fork that the slave cylinder presses against? Got a picture of what I'm talking about in the spoiler. Spoiler: Picture Thanks for your time and have a good day.
My uncle and I have gotten the dozer back together. Started it up, but now when the left steering lever is pulled both tracks stop, same thing happens with the right steering lever. So we started bleeding air from the steering cylinders and valve. Sometimes just air coming out, other times mostly oil. Though one of the times we started it up, it worked properly, when one lever was pulled only one track stopped, and that happened with both levers. Shut it off to bleed some more air, and then started it up again back to not working properly. So our question is what the best way to bleed the system? Also attached photos of where we were bleeding the air. Thanks for your time.
How did you pull the clutch out after unbolting? I have removed the 16 bolts (eight on each side of the clutch) and tried to rig a comealong to pull it straight up. Still can’t get it to come out.
Just saw this. I'm not certain, my uncle did the work on the clutches when I wasn't there. I can ask him tomorrow evening if you are still working on it.
I got it to move! I have been able to move it approx 1.5 inch up/vertically but now it appears stuck again. Any ideas?
See Post #3 by @John C. in this thread. To avoid the steering clutch assembly "cocking over" as it is lifted the brake band should be the fixing point for the lifting gear, not a choked strap around the steering clutch HeavyEquipmentForums