Cat 950B Loader SN 22702660 If the operator applies the brakes, then releases the brake pedal and puts his foot on the floor brakes will work flawless all day long. However if driver hovers on the brake pedal, ( we have random independent truck drivers that load trucks ) they loose brakes for a while even though the air tank is full. We replaced the treadle valve, and replaced the air compressor due to oil loss issues, with no change. I know some of the Cat loaders and skidders had issues with the Air/Hydraulic system especially in the winter, this is a summer issue, thinking there must be a stuck valve somewhere, any help appreciated.
First thing that comes to my mind is something wrong with the air can master cylinder thing whatever they call them. Or a collapsed line somewhere.
I have seen the pistons stick in the master cylinders and cause grief. It sounds like your not getting application air though. There are two treadle valve. Could the second one be hanging up or otherwise causing an issue?
Which treadle valve did you replace, left or right.? Do the truck drivers who operate this loader even know the difference between how the left pedal works compared to the right one.?
I asked the same question to the owner of the machine, and he was not aware there was a difference, I thought one pedal was a clutch disconnect pedal and one wasn't, I have run the loader some and don't think the disconnect is working on either pedal, I believe the left pedal was replaced.
After some verification, yes the left pedal was replaced, also on the left pedal there is a switch underneath that selects clutch disconnect or not, this loader is selected to not disconnect.
In that case has anyone looked at the right pedal.? Attached the Brake System Operation if it's any use to you. TBH to sit with the brake on and the torque converter stalled while dumping is not going to do the power train much good long term. Did the machine owner give any reason why the transmission neutralizer has been deactivated.?
You have a 950b with a switch controlled neutralizer? I thought they were air operated on that model. What is the real serial number? The one at the top should have a letter in it.
When you hit pedal can you hear air release when you release it if so the air part is working my bet would be to replace the master cylinders
22Z was a 950B prefix and I believe you’re correct as to no switch. Simply use the left pedal to neutralize and the right if you didn’t want to.
I ran a 980c that had no brakes. It had the go fast pedal on the right and if you were on a hill, the go faster pedal was on the left.
You are correct, according to Caterpillar, my 7 is a poorly stamped Z. Printed out the brake system operation from Nige, and going to look at machine later today, to get acclimated, Taking my time as it is -8 degrees currently. Interesting looks like 2 master cylinders.
One for front brakes, one for rear. Each axle has a separate service brake circuit. Standard practice AFAiK on all Cat loaders to avoid a complete loss of brakes in the event of a failure.