rear wheels lock up

[coqui]

5600 Serial Number: 424711001 & Above Hoping for someone with the same problem. Problem started with rear wheels locking up and dragging after running for an hour,sometimes several hours. At first no codes. Eventually threw 50-14. Tried disable axle match and unplugged rear speed sensor. No change. Replaced rear speed sensor and worked four or five days no problem and then with some hard work locked up again. Machine lurches and can be moved but usually going up or down hill rear wheels lock up again. Mechanic updated the software and calibration codes showed up and he recalibrated. Calibration codes and 50-14 still scrolling on display. Started to use machine yesterday and ran fine for 3 hours then same problem again. Drive motors were replaced a few years ago.Any insights appreciated.
aloha coqui

 

[Xfaxman]

Any resolution to your problem?

 

[coqui]

Any resolution to your problem?

No Change. We have no bobcat dealer on Hawaii Island. Our mechanic was the dealers mech. He put the bobcat pc on the machine,updated the software and recalibrated. The 50-14 code is gone but the problem persists and the calbration codes keep scrolling. Thinking its electrical. Hoping the mech. comes back to try chase it down.

 

[ruffdog]

If it was the parking brake system goofing up, it seems it would either be the left side or right side, not F/R.

 

[coqui]

toolcat still down. codes 50-34,50-57,50-42 and as soon as step on the brake pedal 50-14. harnesses look ok replaced the speed sensor. runs ok for a hour or more then starts bucking.

 

[ruffdog]

I would be crawling around to clean EVERY electrical connection and dab on some dielectric grease. I would also be looking for any evidence that mice have moved in and chewed on stuff.

 

[PILOON]

Nothing against dielectric grease but I like spraying WD40 into all my contacts and making/breaking each one as I do so.
I have saved many ignition switches that way as well as use it on all my locks and tractor connectors.

WD is non corrosive and provides some lubrication.
The make/break action improves the contacting surfaces by the minimal abrasion created.
The grease could be added after the WD treatment.

 

[myersjc]

toolcat still down. codes 50-34,50-57,50-42 and as soon as step on the brake pedal 50-14. harnesses look ok replaced the speed sensor. runs ok for a hour or more then starts bucking.

coqui I have the same issue and have done some of the same steps troubleshooting. I have not had the trouble codes 34, 57, or 42 but i have had the 50-14. At one point I did find the magnet ring that is just inside from the speed sensor had come loose from the washer it is glued to so I ordered a new one as well as replacing the speed sensor. Right now my most likely suspicion is that may be as the fluid heats up after continuous work the pressure is dropping to low to release the spring brake, or a valve or something for the rear axle is getting sticky when hot??? I have changed and flushed the the hydrostat oil and filters but no help. I am also confused how or why being on a hill can make it worse (mine does this also)

Right now I just fight with it forward and reverse and usually after a frustrating 10 minutes back and forth it will usually kind of pop and release and take off in reverse then I can go again for a while. Sometimes for a hour or more other times for 10 feet all depends on what I am doing

 

[DEWFPO]

Just a thought. Have you looked into the parking brake switch wiring at the control panel? That would be the only other thing I could think of that holds the brake on. I guess it's possible that the switch wiring may be making contact if it's against something that gets hot during operation.

DEWFPO

 

[laurencen]

be worth checking the pressure, add a Tee to the brake line and watch it, when the brake comes on the pressure I assume drops, you could see if its slow drop or like a rapid drop, if rapid more like a solenoid issue