753 Left side drive causes engine to labor and stall

[Buggzie]

Hi everyone I have a 97 753 with the Kubota diesel, sits around alot with not alot of use. Fall of '09 I lent it out to relatives. When they were loading it they said it wouldn't drive straight, had to be full stick on one side and actually feather neutral/reverse with the other. Out on the job site the complaint was that it had strange steering response, but they couldn't be specific as they were not familiar with this type of skidsteer. So I chalked it all up as pilot error ;-)... Winter of '09 I wanted to move some snow, started it and let it idle for at leat 15 min, then headed for my driveway. About 100 feet later it began to slow down, but the engine was laboring hard against it, was as if I was stepping on brakes and full throttle at same time. I let up on the sticks and the engine went back to its normal unloaded state. Start off again, seems ok, then after 20 feet starts to grind to a halt with some pump/drive whining. Got out and noticed a trail of hydro fluid leading back to a puddle where I had let it idle and warm up. Parked it and figgured I'd find the ruptured line another warmer day. Today ... replaced missing fluid (about 2 gallons) lifted cab, started it up.. and nothing.. no leak, no broken lines! Ran the bucket up down, tilt, etc... all seems fine. Backed it up, all seems ok... then drove it about 100 feet and it starts to bog down again, let up and it recovers, moves fine for 20 feet then bogs down and some whining from the pump/drive. Still no leaks! Got the tires off the ground and isolated this to the left drive, will actually kill the motor if you stay on it and don't return it to neutral. Seems to be both foreward and backward, and does make a whining/groaning sound in the hydraulics as if it's laboring to turn those wheels. Inspected chains, wheel bearings... seem free spinning and undamaged, oil level ok. Read oodles of posts, could this be filter blockage, or should I prepare to get involved in the pump/drive? Thanks for any advice you may have!

 

[frogfarmer]

Does your park brake work as it should for both sides? What does your chain case oil look like?

 

[Tazza]

Does your park brake work as it should for both sides? What does your chain case oil look like?

It could be the bearngs going out on the motor carrier, it could be the drive motor too.
You can try swapping drive motors, this will isolate the drive motor of the problem moves to the other side.

 

[Buggzie]

Thanks to both of you.. I looked at the 'brake mechanisms' they seem to be o.k. and do operate normally. The chain oil looked clean, but I think I may have seen hints of brass in it... will check on it again. I was kinda leaning towards the drive motor myself, are the motor carrier bearings a sealed type or do they lubricate from the hydo side or chain oil side. Also is it a brass bushing or roller and or ball bearings? Thanks again!

 

[Buggzie]

ohh... wait a minute... about the 'parking brake'. Just spent some time downloading and reading through a manual for the drive system. I believe I am confusing 'parking brake' with 'traction lock'. The previous owner disconnected the little switch on that orange footpedal, I've always just ignored it. 'Traction lock" is what I believe engages when you lift the lap bar up and get off the seat switch, right?.... I'll have to look into the 'parking brake' as well... thanks frogfarmer, I really don't know how those are behaving.. didn't realise there were 2 braking systems.

 

[bobbie-g]

ohh... wait a minute... about the 'parking brake'. Just spent some time downloading and reading through a manual for the drive system. I believe I am confusing 'parking brake' with 'traction lock'. The previous owner disconnected the little switch on that orange footpedal, I've always just ignored it. 'Traction lock" is what I believe engages when you lift the lap bar up and get off the seat switch, right?.... I'll have to look into the 'parking brake' as well... thanks frogfarmer, I really don't know how those are behaving.. didn't realise there were 2 braking systems.

Buggzie, I'm sorta new at this Bobcat stuff. On my 751 (your 753 is most likely very similar), the "brake" is really a solenoid that engages a slotted wheel which is directly connected to the drive mechanism inside the chain case. The little orange pedal between your feet operates a switch that engages the solenoid in the slotted wheel. Same thing happens when the lap bar is up. The pin is either in or out, no "slight braking" with this arrangement. If it's engaged, the wheel's ain't movin', period. -- The traction lock is some control logic that lets the joysticks move the Bobcat when there's no operator in the seat. Primarily used if you are sitting on a backhoe attachment and want to reposition the Bobcat slightly. Has nothing to do with brakes or slowing any wheel movement. Unfortunately, the foregoing has nothing to do with your current problem, and I can't offer much in the way of suggestions. Looks to me like you are doing the right thing by getting the wheels off the ground and watching them. While it's off the ground, you might also try to rock each wheel back and forth. You should be able to feel the chain slack in each wheel. My wheels rock back and forth about half an inch, as measured at the tread. If you can't feel any slack in them at all, I think that points to a bound up chain drive. Just a guess. ---RC

 

[Tazza]

Buggzie, I'm sorta new at this Bobcat stuff. On my 751 (your 753 is most likely very similar), the "brake" is really a solenoid that engages a slotted wheel which is directly connected to the drive mechanism inside the chain case. The little orange pedal between your feet operates a switch that engages the solenoid in the slotted wheel. Same thing happens when the lap bar is up. The pin is either in or out, no "slight braking" with this arrangement. If it's engaged, the wheel's ain't movin', period. -- The traction lock is some control logic that lets the joysticks move the Bobcat when there's no operator in the seat. Primarily used if you are sitting on a backhoe attachment and want to reposition the Bobcat slightly. Has nothing to do with brakes or slowing any wheel movement. Unfortunately, the foregoing has nothing to do with your current problem, and I can't offer much in the way of suggestions. Looks to me like you are doing the right thing by getting the wheels off the ground and watching them. While it's off the ground, you might also try to rock each wheel back and forth. You should be able to feel the chain slack in each wheel. My wheels rock back and forth about half an inch, as measured at the tread. If you can't feel any slack in them at all, I think that points to a bound up chain drive. Just a guess. ---RC

Bobbie is spot on with the machines being very close.
If the park brake was sticking, you wouldn't move and you'd feel it jumping around.
The motor carrier uses tapered bearings that are lubricated by the chain case oil. Not sure where the brass flakes could be from, all the bearings are tapered roller bearings, not brass bushings.
I'd start witht the drive motor, they aren't THAT hard to move from side to side, its not pleasant, but can be done. When you have the motor off, lift that side and rotate the wheels, they should rotate with ease, no binding. You will have to unlock the park brake first, you can remove the park brake solenoid to make it not engage.