I have a D8R 7XM serial number with a cracked tube for torque converter inlet supply oil. I was wondering if anyone has an idea how to repair or replace the internal tubes. It can't be welded where it is. The Crack is against the case side.
Hmmm, let us know what happens. They were put in there, they must come out.
How about a compression union
I was thinking that might work but it cracked for about 3 inches on the 90 degree bend. It was interesting troubleshooting Trans runs hot. Low torque outlet pressure.
There should be a Special Instruction or other documentation available somewhere for replacing those lines. They are (or at least they were a few years ago) available through the Parts System. We did a number of them over the years on tractors sized between D9 & D11 but an 8 should be no different. What we found was that your dealer Tech Communicator had to first get a factory print of the Case & Frame Group that lists the steel lines in order to get the Part Number. Once the part was ordered I think from hazy memory that the factory supplied the info on how to install. It needs some type of tube expander as best I remember. I'll go digging to see if I can find some details. I know from bitter experience that welding won't work even if the crack is accessible.
Yes we once had a D7R fail a trans right from new because one of a pipe was loose and leaking oil inside the case. Had to get the pipe expander flown in from the factory to get the tube sealed. This was not a tool for sale but had to be borrowed from Cat As Nige said, your friendly local Kramer, Oops I mean Finning will most likely have to get involved in parts, procedure and tooling.
You'll probably have to get some updated information from Cat but as a first step try Special Instruction SEHS8467. It doesn't specifically cover the 8R but I'm betting that one or other of the tube expanders listed there will do the job, it's just a matter of finding out the number of the tube you need and ordering it. As a starting point that will mean you need to get hold of the factory print of the 116-4613 Case & Frame Group via DSN. If the tube is anything other than 1" or 1.25" outside diameter then you'll have to ask the factory for help. You may have to ask the factory for help anyway because the tube expanders listed in SEHS8467 are about $4000 a pop ......... yikes ........ Have a look at Special Instruction REHS1069 which is for D8R 7XM-prefix. It's not for your specific problem but might also give you some ideas. Lastly consult Guidelines for Reusable Parts, SEBF8147, "Replacing Tubes In Housings Installed with Mechanical Joints (Expanded and Welded)"
Also be sure to ask your dealer for some Cat help, those lines should never ever break or crack, they are designed to last the life of the machine. At least that would be my argument for some Cat or dealer policy money. They have dollars set aside for customer assistance, and if you are a good customer or are nice about it, they will usually give some help. We tend to call our friendly PSSR very often, for advice and also help on the 'weird' stuff. Good luck!
With the number of high-drive tractors Cat has built over the years IMHO it's not beyond the bounds of possibility that an odd line can fail. I recall a few, maybe half a dozen, over about a 10-year period, and that was with a dealer population of maybe 500+ tractors. I guess it all depends what the failure mode is, if it's a defect within the tube itself then maybe there would be some factoy help forthcoming, it would probably depend on how many hours was on the tractor. Also it would be dealer Tech Communicator who would be pushing the case to the factory rep for support rather than the PSSR.
You're right Nige, but normally we would use the pssr to get the ball rolling, and usually he is in our corner to a degree. At any rate, worth a try... all they can do is say no. And if the help you get is in the form of a tool loan to swell the tube, all the better.
Thank you very much for all the info. I remember years ago when I worked for the Cat dealer finding a D10 with a cracked tube but I wasn't sure how we repaired it . I'm afraid how long it will take to get all the balls rolling. The customer wants to use a compression fitting to get it up and running. It may work because the line only runs 145 psi max. It's also very easy to R&I the trans on these machines so we wouldn't be out much trying to patch it for now. I'll let you know how it works out.
I feel your pain, wanting to do it right but pressure from above dictates different. Reminds me of the the old saying "OK, that's how you do it right. Now let me show you how to do it wrong". Is there enough room to get a compression fitting in there without fouling anything..? Can it be tightened OK..? And also (despite the fact I realise a piece of tube will have to be cut out to get the compression fitting in there) is the split in the tube short enough to do this and still remove all of the defective section..? To do it the factory way is going to need components removed (as well as the transmission) because the tube expander goes into the tube from the outside of the frame at both ends of the tube.
Yair . . . Never seen inside a Cat like that before but I have seen inside a lot of different transmissions and gear cases and I would have thought "conventional" engineering practice would be a nipple through the housing with inner pipes and outer pipes with flared or compression fittings . . . I wonder why Cat "did it different"? Cheers.
I would be looking at Swagelock fittings. They are Stainless steel,good for 5000kpa+ pressure and extremely up-market compression fittings. We use them on high pressure Gas pipe lines on theregulator sets etc. you could use 2 mi x compression fittings,comp end onto your two cut pipe ends and order a flexi pipe connector that bolts onto the male end.
Scrub: I would be thinking their system eliminates any mechanical fittings that could later fail'loosen in side the box,the only possible failure being the one were discussing,pipe.
Yair . . . Gotcha Garrie Denny I suppose that's the reason but to me a nice set of compact Swagelocks would make for nice serviceable plumbing and help break up harmonics. At any given set of revolutions and load those pipes would pulse/vibrate at different rates. Cheers.
Scrub, those tubes don't fail very often, especially when you consider the number of tubes per tractor multiplied by the number of tractors out there because all the high-drives have them. The design functions just fine. Very occasionally you get one that leaks, usually because of a defect in the tube itself, but it's not frequent as evidenced by the OP (who IIRC is an ex-Cat dealer tech) not being sure what the procedure was to make a repair. Like I said it's not at all common for these things to fail, so IMHO it doesn't need re-designing.
Yair . . . Gotcha Nige . Point taken, it just looks really strange to see hydraulic tubes disappearing into a housing. (big grin) Cheers.
My heart goes out to mobiltech, what chanch would you have of owning a machine where the pipe failure,Most likelyduring manufacture of rolled welded metal gets put in your box in that particular spot ?, or possibly a stretching problem when the part was manufactured ? Bent ? but in a straight line failure it sounds like metal failure, either way way sorry pal.
these tubes are servicable the pipe ends has to be flared using suitable mandle
We got the D8R together and the torque and lube pressures are good again. We used swedgelock fittings with a new section of pipe bent to fit.
Nice-looking job.
Yair . . . For sure, you done well Mobiltech , looks like a bought one! (big grin) Cheers.
And Loctite I hope! Sweet! :drinkup
You don't need locktite on swageloc fittings The can be un assembled and re tightened up to 5 times and are guaranteed not to leak.
Thanks for all the support guys and thanks for the proper spelling on the swagelok fittings. Im pretty happy with the results and wouldn't hesitate to do it that way again. I wish cat would have a better schematic of the actual internal flow for these machine to make troubleshooting easier. By following their schematic on SIS you really can't picture the internal lines as being a problem. I found it by capping off all the external valves and lines and then putting air pressure to the internal parts. If I hadn't seen these lines crack before I would have been really second guessing myself. There is a thread on this forum about field service guys and what they need in the field . This makes me think you really need to have the experience and the confidence to follow your instincts on jobs like this or you will just be going in circles. It also really helps if the operator leaves you alone with the machine so you can concentrate on the problem without all the jibber jabber.
LOL, Oh yeah, I would trust that inside a case.... no offense Garrie Denny.
Mobiltech, you are exactly right, if you can get a mental picture of how it's supposed to be, how it functions when it's right, and follow that logically to what causes it to act the way it is, you have the answer even if "experts" are telling you it's impossible or "we checked that" or "we replaced that already". Believing in yourself is half the battle sometimes. Well done.
Job looks very top notch
Funnily enough Swagelok have a plant only a couple of miles away from my house. http://www.aerospace.co.uk/capability-search/member-profile/1968 I'm going to remember that for the future as an alternative to replacing the complete tube and having to procure the special tooling necessary to expand it into the rear frame case. If it was inside that case with a transmission to remove if a leak developed I think I'd be Loctiting the unions as well just in case. Earthmoving equipment tends to vibrate far more than aerospace which is the primary use of Swagelok fittings.
Good job!! and on an elbow like that it will take care of expansion and contraction as well.