]Hi guys I have a T190 here in New Zealand and have run into a bit of a problem I was working a few weeks ago on a job and noticed hyd fluid comming out of the RHS drive motor. I pulled the track off and traced the leak to one of the large 90' fittings that screw directly into the drive motor. There is two of these large feed lines that come from the body of the machine, the one leaking is what I would call the upper one that is towards the front of the machine I removed the 90' fitting and located a blown O ring - No problem so I replaced it , put the track on and go back to work.... for about 15mins untill the leak was back. I pulled the track and it was the same fitting, with the same problem This has now happened 5 times in perhaps 5 hours of running time !! ARGH I have tried a new fitting, a couple of sizes of O rings but all only last a few minutes After reading up on this forum I located the Case Drain filter and removed it - there was a few small specs of metal but not a huge amount Is there a bypass or overpressure valve in the drive motor that might not be working or is this the signs of a drive motor meltdown which I have read so much about Attached are pictures of the fitting in question, the case drain filer insert and the o ring ANY help would be aprecaited :Banghead:Banghead Cheers !! Byron
change your male 90deg fittings, male fitting must much fit to female fitting from hose. observe from your fittings picture
The o ring in your photo does not look like it is damaged by heat. It looks more like the fitting is not being installed correctly and is not compressing the o ring correctly. Which leads to seal failure. How are you installing the fitting? Have you checked the port that the fitting is screwing into? I have seen fittings like those installed incorrectly by people several times. With that style of fittings I always use the recommended size and grade of o ring for the fitting and check the port it goes into very closely for nicks or burrs, then lube the o ring with type of fluid it will be sealing against. This helps keep them from tearing if they stick to the metal. Then on those style fittings back the jam nut and washer up away from where the o ring goes. The o ring has to rest in the thread less area that you can see below the washer under the nut. When you install the fitting into the port it should screw down very easily. If you look at the fitting and the port you can see about where the fitting will have to stop in order for the seal to wind up at rest in the thread less area beneath the nut and washer. The fitting has to screw in to the port far enough that the lower threaded section of the fitting is well below the tapered section of the port. The area between the two threaded sections on the fitting is wide enough to allow the fitting to be screwed in completely and still turn further enough to line up with the line. After all of the above steps are done correctly you can jam the nut down compressing the o ring and locking the fitting in place. I know this is a lot of text for a very simple job but you would be surprised how many people don't know how to install that type of fitting. With all of this being said if all steps are performed correctly then those style fittings are almost impossible to get to leak. I have seen the drive motors on those machines smoking from being so hot due to a failure and I have seen pressures set incorrectly or other problems cause pressures to spike way above what they should be and still in the end the o ring on the fittings did not fail. Let me know if any of this helps and if it does not get us some photos of the port on the motor. There is a lot of brilliant people on here so I am sure one of them will help you out if I can not.
I have ran into this before....... If the fitting in not screwed into the drive motor far enough you force the O ring out of its groove once you tighten the jam nut. Smitty gave you some good advice.
Two things I have to add; 1) Are you using a 900 series "o-ring Boss" replacement o-ring? If you use any other series, 200, 300, you'll blow it everytime. 2) Look closely at the washer on the fitting. I've seen many adjustable fittings that weren't installed properly (as smitty said) and it bends/distorts the washer. That washer has to be completely flat or it will cause o-ring failure.
Thanks guys - and especially to Smitty Looks like the problem is one of me not putting it back together correctly..... Ill pull the track of again and give it a go On the plus side of things I am getting very good and getting the tracks off now!!! So there is nothing in my eariler post or pictures that leads you to beleive that it is a failure of the drive motor itself ??? Because thats what the Bobcat agent here was telling me !!!!
NZT190, I wouldn't say it's a motor problem until we know for certain the fitting and o-ring are installed properly. I agree with smitty, many folks don't know the proper method for installing adjustable SAE hydraulic fittings. Not because they're sensless...just they don't know. When the fitting is removed, I always back the jam nut away from the washer. Then I push the washer towards the jam nut until it bottoms out on jam nut threads. Hold the washer in that position, and turn the jam nut until it slightly pushes on washer, then fit a new o-ring. The fitting is ready to install now. Lubricate the o-ring and screw the fitting in until it seats the o-ring slightly by hand, but do not allow jam nut to turn. If the fitting is not yet in the position you need it to be, don't crank it around with a wrench. Instead, uncrew the fitting until it's in the proper position and crank down the jam nut to seat the o-ring. Also, correct o-ring is imperitive. 568-900 series only. Nothing else will work.