Tenn_Blue
Silver Member
- Joined
- Nov 14, 2007
- Messages
- 154
- Location
- N.E Tennessee
- Tractor
- Deere 2320, Bobcat 322 mini-ex, Bobcat 763 skidsteer
Rebuilding a track drive motor on a Bobcat 322 excavator. Had a bad oil seal on the back side of the planetary gear section, and a bearing going bad. Hydraulic motor section is fine.
My question: There are six gears (three gears each on two plates) that each turn on shaft stubs with uncaged needle bearings between the gear and the stub in the planetary section of the motor. Each has enough play between the gear and stub to be able to wiggle the gear side to side about 1/16 inch. All have about the same amount of play in them. Gears mesh fine under load (turning the input shaft by hand from where the hydraulic motor shoud be), and everything seems to work ok. Should the gears have this much play or are things really worn?
The planetary section had a lot of sludge in it (again, the hydraulic side was fine) when disassembled. Motor was a little slower than the other track, but was working when removed to replace the leaking seal. Excavator has about 2500 hours on it. It was originally a rental unit, so has lived a hard life, but is in ok shape aside from some pin slop in the boom and bucket (which I plan to fix this winter).
I have the service manual, but it doesn't have any specs for side play or gear mesh %. My local bobcat stealer suggests I get a new motor (to the tune of several thousand $$$), or bring it in for them to fix it (again, big bucks!!!) - thats about all he will say. This is for a farm machine that only gets occasional use, it's not a daily runner or money maker.
I have a lathe, so could open up the gear hole and use oversize bearings, or sleeve the stub shaft if there is not supposed to be any play between the gear and the shaft. But the fact that all the shafts have the same level of play makes me think it is designed in. There is some wear in the shafts and the sun gears, but not an excessive amount - not enough to acount for that much free play...
I'm tempted to replace all the bearings and seals and slap it back together, but it wouldn't be that much more work to do the machining while everything is apart anyway IF IT IS REQUIRED. I just don't know what the original tolerances were. Never worked on this type of planetary before, so don't know what it should look like. Replacing the bearings and seals is easy with the manual.
Sorry this was such a long post! Anybody have any info on these motors and the planetary gears in them? Thanks in advance...
My question: There are six gears (three gears each on two plates) that each turn on shaft stubs with uncaged needle bearings between the gear and the stub in the planetary section of the motor. Each has enough play between the gear and stub to be able to wiggle the gear side to side about 1/16 inch. All have about the same amount of play in them. Gears mesh fine under load (turning the input shaft by hand from where the hydraulic motor shoud be), and everything seems to work ok. Should the gears have this much play or are things really worn?
The planetary section had a lot of sludge in it (again, the hydraulic side was fine) when disassembled. Motor was a little slower than the other track, but was working when removed to replace the leaking seal. Excavator has about 2500 hours on it. It was originally a rental unit, so has lived a hard life, but is in ok shape aside from some pin slop in the boom and bucket (which I plan to fix this winter).
I have the service manual, but it doesn't have any specs for side play or gear mesh %. My local bobcat stealer suggests I get a new motor (to the tune of several thousand $$$), or bring it in for them to fix it (again, big bucks!!!) - thats about all he will say. This is for a farm machine that only gets occasional use, it's not a daily runner or money maker.
I have a lathe, so could open up the gear hole and use oversize bearings, or sleeve the stub shaft if there is not supposed to be any play between the gear and the shaft. But the fact that all the shafts have the same level of play makes me think it is designed in. There is some wear in the shafts and the sun gears, but not an excessive amount - not enough to acount for that much free play...
I'm tempted to replace all the bearings and seals and slap it back together, but it wouldn't be that much more work to do the machining while everything is apart anyway IF IT IS REQUIRED. I just don't know what the original tolerances were. Never worked on this type of planetary before, so don't know what it should look like. Replacing the bearings and seals is easy with the manual.
Sorry this was such a long post! Anybody have any info on these motors and the planetary gears in them? Thanks in advance...
