Good evening, just joined up, I am having some problems with my hitachi ex60, mfg number 107-17990. Today while working, it sprung a large hydraulic oil leak. Hydraulic oil leaked out soaking the inside of the sprocket with oil, quite rapidly... I carefully removed the fittings from the motor and capped them all off, thankfully I had the caps/plugs on hand, thus avoiding my entire reservoir from siphoning as it did drop a few inches while sitting parked not running after I discovered the leak. Motor had this part number on it: model HMGBO83A mfg 090-17990. I have done some searching, and have found that this is likely to be the brake piston seal. Possibly duo cone seal as well. Here are some questions I have that hopefully someone who has dealt with this repair before can answer, I have a general idea but need some guidance. 1- remove 6 hex head bolts and the hydraulic motor will come out of the planetary.(Lines already removed) At this point, the piston seal kit can the replaced. Simple as that, the motor can come off the machine with the track still on, planetary still on, still sitting on terra firma, correct? 2- how can I determine at this point if my duo cone seal is damaged? Is it safe to say at this point its no good? If I check my planetary oil, and it is still straight gear oil, is my duo cone seal is still in tact? Basically will a leaking brake seal contaminate the planetary? will check the level/condition tomorrow and see what it tells us, and report. 3- track, planetary, sprocket etc all need to come off to replace duo cone seal, there is no way to do this on the machine? Thank you, hopefully with your guidance I can get through this relatively easily. Any part numbers, advice, experience is welcome. Machine only has 4900 hours. -mpar
One more question, how does the brake work in these motors? Does it automatically apply when you let go of the drive sticks? How does it apply the brake, from hydraulic pressure? Or does it use hydraulic pressure to release it allowing movement?
We'll start with this question, they're spring applied for safety, hydraulic pressure automatically releases the brake when you start to move the track. Yes, if you're losing hydraulic it usually is brake seals. As to the duocone/floating seal, you may be lucky and the pressure caused it to leak but didn't damage it. You will have a hub full of hydraulic oil, after you repair the hydraulic leak drain it, put some gear oil in and run for a short time long enough to warm up a bit anyway, then drain once more and refill with correct lube to proper level. You got nothing really to lose by trying it and checking to see if the seal heals up or keeps puking. In my experience you can change hub bearings and/or duocone seals without removing the drive from the frame, just pull the hub off. May or may not have to split the track, depends on how much slack you can get and if perhaps the sprocket will either wiggle off or can be split into two halves for removal. YMMV
Ok, sounds like I am on the right track.. The previous owner has recently done the brake seal on the other side, and it was just the brake seal o-rings. So maybe I will get lucky and the side that is now leaking will seal up with some o-rings. Im sure it will make more sense when I get it apart. Easy enough to pull the motor, replace o-rings, start it up and see what happens.
Well here is the culprit... The planetary was low, and all hydraulic fluid. So when I get parts I will replace brake o-rings, put it together and hope my duo-cone seal is still good to hold back the gear oil. If it slowly leaks gear oil, just keep it topped up, and no driving through water.. We shall see..
Yeah, I'd say the previous owner got his money's worth out of that piston seal....