Hi there, Need some help with my dozer. We just replaced the steering clutches and brakes ,started it up but it wont move in forward or reverse. Transmission shift cables are activating as they should. The guy helping me seems to think its something to do with the hydraulic lines that were disconnected from the steering clutch control valve when clutches were replaced and that the system needs to be bled in order for the transmission to shift. I thought the transmission should operate and drive the machine forward or reverse regardless of the steering clutch hydraulic controls. Checked brakes as well t make sure they were not too tight. Any ideas? Thanks, Doug
Does the motor come under load when put into drive and was the dozer driving before the clutches were replaced . By replacing the clutches do you mean the plates inside the clutches or the whole unit ?
no, engine doesn't come under load when put into drive. Yes, the dozer was driving forward and reverse ,just had steering issues. We drove it into our shop to do steering clutches and brakes. We replaced the plates inside the steering clutches on both sides. We also replaced the brake bands.
There should be test points to check oil pressure . I take it the drive shaft spins . I have seen it written here that the transmission can have some air put in through the filler cap enough to push oil into the pump , I've never needed to do it on mine , that would need the transmission vent blocked for a little while , apart from checking all the hydraulic lines , oil levels etc its the easiest thing to do , just a few pound pressure while the motor is running . Wrapping an oily rag around the air gun is enough . I have a link to a Komatsu parts web site that may show your test point plugs but not the pressures on a near dead laptop , I'll try and recover it this evening .
ok, we checked the hydraulic lines coming from the transmission to the steering control valve, like you suggested. They were connected backwards. We corrected them and the dozer now moves forward and reverse! Thanks for the help !
Good to get it going . Here's the parts link for your dozer , there is a search tab on the page if the model number does not match https://k-part.777parts.org/catalog/komatsu/d21p-6r/