Operation - Section 3 10/00 OM3023 Page 3-14 Operating Instructions BRAKE RELEASE Releasing Parking Brake And Emergency Brake After Being Actuated In An Emergency 6. With parking brake disconnected, remove block- ing and immediately move the truck to a safe place. Refer to INSTRUCTIONS FOR TOWING THE MACHINE. If the pressure inside the air tank drops abnormally due to some problem, such as leakage of air from the air circuit, the parking brake and emergency brake are automatically actuated. If the air system is not operating, the service brakes will not apply; this is very dangerous. Be sure to tow the truck at low speed, keeping the engine running (if possible) and always be ready to steer.
RELEASE OF PARKING BRAKE The parking brake is a dry disc brake mounted on the rear drive shaft at the differential input with two (2) spring-applied, air-released calipers. Each caliper is individually applied/released through separate air chamber actuators (spring cylinder assemblies). If the parking brake can not be released after its emer- gency application - even if the parking brake valve lever is put in RELEASE position - take the following actions to release the parking brake: Refer to Section 4, Lubrication & Service; Parking Brake Inspection and Adjustment , for instructions for reconnecting and adjusting park brake.
RELEASE OF EMERGENCY BRAKE When the emergency brake has been applied, do not continue to drive the machine. This will cause seizure of the brake discs and linings. 1. Block disabled truck to prevent movement and confirm safety in the surrounding area. 2. At the parking brake relay valve, remove both air hoses (4) connected to the air chambers of the parking brake spring cylinder assemblies (5). If the emergency brake can not be released after its emergency application - even if the emergency brake valve lever is put in RELEASE position - release the emergency brake in the following manner:
Before releasing the air pressure from the emer- gency brake reservoir, confirm safety in the sur- rounding area and put chocks against the tires. 1. After making preparations to tow the machine, pull rings (2) on the 4 drain valves on the front air tanks to release the air pressure. 2. After exhausting air pressure, release rings (2). 3. Drain the rear air tank by pulling and holding the ring on the air drain valve mounted on the frame in front of the right rear suspension. Keep drain valve open until all air is exhausted from tank. This will allow the emergency brake to release. 3. Connect these hoses together using a "tee" fit- ting with compatible thread ends. 4.
Connect third connector of "tee" to a hose from an air supply of sufficient capacity to release calipers. Apply air and release brake. 5. With parking brake released, turn adjustment bolt (2) counterclockwise, and check for "play" in linkage (3). Remove pin (1). Repeat for other caliper. Disconnect air supply. RELEASING EMERGENCY BRAKE 1. Air Quick Disconnect 2. Drain Valve Pull RIngs