STOP 9G6419 - Caterpillar

Introduction
The issue that is identified below does not have a permanent corrective action. Until a permanent action is known, use the interim corrective action that is identified below.Problem
Illustration 1 g02944436
725 S/N:AFX1-1178 730 S/N:AGF1-1091Parking Brake Valve on the inside of the rear frame on the right side, forward of the center axle.
Illustration 2 g02944321
735, 735B, 740, 740B, 740 EJECTOR, and 740B EJECTORParking Brake Valve on the inside of the rear frame on the right side, forward of the center axle.The parking brake on the listed machines might fail to release due to electrical hydraulic or mechanical issues.Troubleshooting of the brake system may indicate that brake system pressure is correct. Troubleshooting may also indicate the operation of the solenoid for the parking brake valve is correct but the release pressure is too low. Insufficient release pressure may be due to an issue with the parking brake valve and servicing of the parking brake is normally the correct action.Contamination of the orifice in 222-5609 Elbow (A) can restrict or block oil pressure to the parking brake valve. Contamination in the orifice can stop the parking brake from releasing.Solution
Before replacing the parking brake valve, check the 222-5609 Elbow (A) which has an orifice that can become obstructed with contamination. If visual inspection of the elbow is not conclusive, replace with a new 222-5609 Elbow or temporarily use a 6V-8625 Elbow that has no orifice.