[kaptain]

Richard, the parking brake air valve will not stay when pushed in to release the brakes. It reacts as if there is not sufficient brake air, but I have 120 lbs. After several attempts , it will release and stay in the released position. I was concerned about a wheel having a dragging brake, but I shot them with the ir gun after driving a few miles and all is well. It does feel as though there is initial resistance after being parked.

I have a similar problem with my parking brake, described below. 

1) Start the engine, and wait until air pressure reaches about 115 psi. Then I push the yellow “Parking Brake” in. But no matter how forcefully I push the knob, it simply won’t go in, and the “EMERG BRAKE” light remains on.

2) If I turn and twist the knob left and right while pushing hard, it starts to go in a little bit (a hissing sound can now be heard). Continue twisting and pushing. I can occasionally get the “EMERG BRAKE” light to go off.

3) sometimes, I am not that lucky getting the brake released, so I continue twisting left and right while pushing while doing this, I can see the air pressure start to drop, and it goes down and stabilizes around 75 psi. I understand the brake won’t release at this low pressure, so I pull out the knob and let the air pressure rebuild to about 115.

4) Some other times, I push and twist until the "EMERG BRAKE" light goes off. To ensure it's fully pushed in, I push it again and harder, then the ""EMERG BRAKE" goes back on again.

5) If I do eventually get the brake finally released,  pulling out the knob is easy. And this set the "EMERG BRAKE" light back on.

6) Last year, when I had my 701 at the Cat repair shop, I requested to check and fix this problem. But the tech didn’t do anything about it, yet charged 3 hours of labor for “looking at the parking brake”. When I questioned this billing, the shop admitted 3 hours of looking without doing anything about it is excessive, so the labor for this part is reduced to 1.5 hours.

Now my questions are:
A) Does this appear to be the problem with the parking release valve or something else?
B) what is the part number of the parking release valve, and where can I purchase it (besides Newell)?
C) What other components in the brake system could cause difficulty in releasing the parking brake when air pressure is at 115 psi?