We have an older Cat 277 tracked skid steer and one of the final drives needs repairs. We don’t want to replace the whole thing, just repair it. Our problem is finding the housing or getting it machined. I have a part number from the housing (178438A) also TBF A is stamped on it but I have had no luck finding one or even who originally manufactured that part. They obviously repair these things as you can find a complete reman final drive. Cat has no breakdown of this part available. Someone must supply this part somewhere. I can get all of the other parts to rebuild it myself.
I have bad news for you on a a couple of fronts. 1. The housing is not available as a spare part. See the attachment, anything not specifically listed in the parts listing is unavailable as a separate part. It's not unusual for this size of machine. You may have some luck enquiring with a Rexroth Hydraulics dealer, a lot of the early-model drive motors, etc, were manufactured for Cat by Rexroth. 2. IMHO, based on experience of this particular product line, the data plate on your machine is not genuine. To further investigate the issue please can you post a photo of the plate taken from a bit further away, also photos of the CE plate and the engine data plate.
Likely any company that remanufactures these units bought a brand-new one initially to function as a pattern and took all the relevant measurements from that unit. The other possibility with the remanufacturers is that a damaged housing makes a unit "not fit for repair" and the customer gets no core credit.
I will do that as soon as I can get to the machine again. Thank you for your assistance.
What needs to be machined? And how much?
The part with the splines on the inside. The splines need to be welded and internally broached.
I see damage on some of the splines but from this angle I can't make out the full extent of it. Are the splines also worn down so there is too much play? Or is there just damage on some of the faces where debris got in in there? Sometimes minor face damage is acceptable but better pics of the spline damage is needed to make a better assessment. Really depends on how the male spline interacts with it too. Any sliding action with the splines when in use or just stationary used to transmit torque?
To be honest if that was mine with that level of spline damage it would be getting a reman final drive - not necessarily an OEM one. But if you want to press on don't let fear stop you. What do the mating splines on the shaft look like.? Any good machine shop that specializes in spline cutting ought to be able to identify the femal spline in the hub from the male spline on the shaft.
Custom splines isn't exactly a common capability for machine shops. Turning off and welding up the inner race is easy. But then getting (or fabricating) the right broach and broaching machine or shaper to make the inner splines is a whole other story. Can also do EDM but engineering costs start to add up real quick for a one off part either way. I'm still not convinced the splines are toast- need more pics of both the female and male parts. I think the main question is how good of a repair is needed? If needing to get another few hundred hours out of the machine while waiting for a better deal on a used or rebuilt drive, then maybe it's worth it to file the burrs down, toss in the rebuild kit, and run the drive (again) to destruction. But if splines are sheared off...well, that's another story.
It just dawned on me this morning that laracraft328 should post this question over in www.practicalmachinist.com . That's the HEF for machining. I'm positive there will be definitive answers on who, how, and where to machine out new splines for that flange.
IMHO it would be a case of comparing the cost to repair the existing hub plus no warranty consideration of the drive motor after reassembly versus the purchase of a complete Reman drive motor assembly with warranty. I know which option I would choose but YMMV.
Before you get too carried away here, contact Flint Hydraulics in Memphis with the complete final drive part number. You may be happily surprised at what an aftermarket final costs. I wouldn't even mess with what your trying to do considering the cost and downtime alone.
I will definitely try to get some better pics of the spline and post them on here. to me there is excessive wear all the way around. The shaft splines are not damaged only the inner housing splines. Thank you for your help.
With that level of spline damage, a Reman replacement final drive every day of the week. Refurbishing those splines is guaranteed to cost more than a replacement unit.
I bet the repair costs wouldn't be much different than replacement.
I bet the repair cost of the hub would be a significant order of mangitude greater than the cost of a Reman replacement drive motor group. Machine shop time, especially when it comes to cutting splines, doesn't come cheap. Let's face it this isn't a job you could do on a centre lathe.....
Very true. I don't know what's involved with cutting splines but I'd imagine its much more complex than work done on a lathe or milling machine.
Thanks for the additional pics. I'm starting to understand how all this fits together based off Nige's drawings. These are splines for the brake pack and it appears some of the outer brake discs (part #13) spun and sheared off some of the female splines, correct? So these splines only provide braking? As to keep the machine from moving? Or do they lock (brake) so planetary gear can provide the torque to move the machine? Clearly I'm not a final drive guy but this failure mode has me puzzled on why only about half of the female splines got damaged...
It's more about this being inner splines which effectively prevents a milling action with a rotating bit. Outer splines can be machined in many ways because the machine and bit used to make the splines stay outside the piece being worked so you have a lot of room for the spindle and rotating bit. Smaller, inner splines are usually broached with a long specialized bit pushed down in one stroke. You can also use a shaper for larger diameter splines which uses a back/forth motion. There is a attachment for a milling machine called a slotting head that converts the rotating motion of the spindle into an up and down movement so it acts like a mini-shaper. There are other ways like laser cutting, EDM, sinker, programming a CNC lathe to act like a shaper, etc. but these require an expert with knowledge...not just a random machine shop. The splines in question can be redone but the trick is finding a machine shop with the right equipment and old-timer expertise. I think the OP has already found that out which is why this thread exists. Again, if the OP wants true expertise on this subject (and more than likely find someone willing to do it), they should post this on www.practicalmachinist.com . But...biting the bullet for a reman drive is probably the easiest, safest, and quickest route to getting the machine up and running. Just no idea on costs for this type of drive.