OK HEF Brain Trust I need your help. We have a D11N, S/N 74Z279, that has an issue with the right steering clutch. Operator called me friday, said right track wasn't pulling. Told me last time it was trash in the control valve from a well used clutch they installed awhile back. Stuck a gauge on it, only had 80 psi. Both brakes and left clutch were within spec, although on the lower end. I pulled the valve, disassembled the spool, found nothing other than a couple small filings, had to have my glasses to see them. I was told last time a different mechanic rebuilt the valve (I have worked around him and he makes me want to jump in front of a train :Banghead. I pulled the other spools and noticed the other three springs were taller siting there in the caps. Measured all four springs and they're withing spec. Measured shims, right clutch spool was 6.5mm, the rest were 13.85mm. Cleaned it all up, reassembled, added shims to get right clutch spool to same height and approximate tension, checked all my o-rings on the mount plate as well. Checked linkage adjustment to make sure the lever wasn't holding the spool open a smidge. Ran the dozer, still low on the right side. Swapped spools with left side. Still low on right. Pulled valve again, took to the shop, cleaned EVERYTHING in my automatic parts washer. Reassembled. Installed, had a little more pressure but not spec. Decided to run the machine and see what else it might show me. I noticed that it would slowly build pressure up to 300 psi. Once you moved the shift lever from dead center of the gate but not into F or R my pressure would drop to 60-80 psi. Moving in gear straight line it's 100-120 psi. I also noticed if you come to a stop, go to neutral, then pull the right lever to release the clutch pressure the track relaxed like it was under tension. At this point I suspect the used steering clutch because it made enough trash this is the third time the valve has been cleaned. It was also so bad owner didn't pay for it. I'm beginning to think it's bypassing oil faster than the pump can keep up. I also suspect the priority valve but that wouldn't explain why the other three pressures are ok. I'm open to any and all suggestions. My gut tells me it's the used steering clutch, most likely a seal. Here are my questions..... Where does the oil from the valve to the clutch go? Does it deadhead in there or have some sort of return galley? It's hard to tell from the book. Is there a way to test the loss at the seals in the clutch? What is the possibility the pump is weak and can't keep up with leakage in the clutch? In a perfect world there wouldn't be any leakage but the fact that it takes so long for pressure to build tells me it's going somewhere and I feel as though the valve and spools have been eliminated. What does the drop when the shift lever is moved off center tell us? Priority valve issue? What does the residual tension on right track tell us? Anything? Anything I've missed? First thing tomorrow I'm going to check the filters. Oil is dirty and could stand to be changed, planning on a sample to see what's in there. I really would like to get four gauges and watch all the pressures and see if they act up under various conditions. Maybe a fifth and watch priority pressure as well. Thanks in advance for your help!!
hi,first off I would change oil and filters and check screens and cut open filters for inspection. this will determine next steps. if the filters and screens are clear I would do a complete pressure check of the transmission. I would repeat the tests operating each steer lever and service brake in turn ,if you find that the results change as you operate the controls I would repeat trans test with brake steer valve blocked off this will isolate brakes and steering from transmission circuits
Thanks Mark. Here's an update. Pulled filters and screens, nasty is all I can say. Tons of shiny goldish colored crap and even a small metal flake or two. Double checked all my pressures, Trans, priority valve, lube pressure etc. All are within spec except the right clutch pressure, 200 psi cold oil, lucky to get 100 psi with hot oil. I'm 99% sure it's the clutches or seals bypassing. One other mechanic I know that's sharp on this stuff seems to think it's in the clutches too. Even picked the brains at local Cat house and they seem to think that's what it is. My only other thought is the get a flow meter and plumb into test port and return into filler tube and see what kind of flow differential I have left vs right. I will post updates as I know and maybe we will all learn something new!!
hi in earlier post you said trans pressures were low . to check for leakage at clutches, isolate clutch and brake valve from trans circuit and connect cat brake release set up to steering clutch test port. use procedure in operators manual for hook up . if you don't have cat brake release gear use portapower with separate low pressure gage and isolator valve teed in to line. operate pump and try and build up to test pressure. close isolator valve and watch for pressure drop Mark
I thaught on all of the high track clutch and brake configuration machines that the clutches and brakes were pressure released and spring applied ?. So why would you want any pressure when not turning, am I wrong ?
Hi,the brakes are spring applied and pressure released, the steer clutches are pressure applied
sounds like your steering clutches are going out
So I have been wrong all this time or is it just on certain sizes/serial number ?
hi , to my knowledge all of the high tracks have spring applied brakes and pressure applied steering clutch's Mark
Hi all New clutch/brake assembly should arrive tomorrow. I've got it ready to pull the old one and swap parts on the final and slap it back together. In the process of building a rig similar to Cat that is adjustable to allow level removal of the entire assembly from the machine or a rebuild of the final on the machine. Now I have two worn out clutch/brake setups to rebuild. Have the local Cat house pricing all the parts to rebuild them. I'm curious how proud they'll be. The o-rings and a few other odds and ends to make this swap surprised me price wise. Worst part of this endevor is the heat right now. 97-100 temp and 105-110 heat index. Yuck. Junkyard
Thought I'd relieve the suspense lol. Parts arrived Thursday afternoon. Got everything swapped Friday. Went back early yesterday morning and got the track back on. Fired it up, pressure was good. Operator ran it for the day and I heard zero complaints. Thanks for everybody's help. Not much to say here but a pet peeve of mine is an incomplete thread. For petes sake tell us what worked, didn't work, if it sold, blew up, burnt down whatever lol. Kind of frustrating to give advice and see nothing else after. As a great friend of mine used to say....Toodle-oo. (RIP Mike)
Thanks Junkyard. I agree about your sentiments about feedback
I also appreciate the feedback. I echo your sentiments. Even though I know nothing about any Cat that new I followed this thread with interest.
I may fire up the laptop and post pics of anybody is interested. I haven't torn the old on apart yet but it did come out with some broken bolts and sure looked like crap. I can't believe the owner stuck it in looking that bad but at the time I think he was in a pinch. I sent some pics of the cat lifting rig to a fabricator the owner uses. What I got back did the job but needs to be reinforced and modified slightly. It's not balanced quite right for the entire final and clutch assembly. I threw a strap come-a-long on it for a little extra piece of mind until I can reinforce it. It was also ALL my crane wanted. Almost didn't have room to lay it over to swap the clutch. Kind of like a dog chasing a car, I've got it out now what the heck do I do next! Haha. It was miserable hot too. Made for a loooong day. Junkyard
+1 on the feedback. A Cat that new...? I'll have you know that D11 is 30 years old if it's a day .....
Yair . . . To us dinosaurs anything with a high-track is new. (big grin) Cheers.
You guys kill me!! Here are a couple pics. I always considered myself a solid mechanic. After being a member for awhile and being exposed to some truly gifted mechanics I barely feel qualified to change my youngest boy's diaper! HAHA Junkyard