YOKE GP 1283339 - Caterpillar

Illustration 1 g00637988
(1) Knob (2) Valve body (3) Spring (4) Orifice (5) Outlet port to the housing assemblies (6) Inlet port from the air tanks (7) Exhaust port to the atmosphere (8) Valve assembliesThe control valve (parking brake) controls the operation of the parking brake. The parking brake is located on the output shaft of the transmission transfer gears.The control valve (parking brake) has control over the supply of air that flows to the parking brake. When knob (1) is pulled to the out position, the air line to the parking brake chamber is open and the air exhausts to the atmosphere. This permits the parking brake to be applied.When you depress knob (1), the air flows from the air tanks into the parking brake chamber. This releases the parking brake.The knob of the control valve (parking brake) will be in the pulled OUT position when the machine is started or when there is sufficient air in the tanks. Valve (8) is in contact with the upper face of valve body (2) in order to block the flow of air to outlet (5) and exhaust (7). When valve (8) is in this position, pressurized air is allowed to reach normal operating pressure in the air tanks and the parking brake is applied.When the alert indicator for the brake air pressure deactivates on the EMS panel and the action alarm stops sounding, normal operating air pressure has been obtained. The operator must depress knob (1). The knob must remain depressed in order to release the parking brake.
Moving the machine with the parking brake engaged can cause excessive wear or damage to the brake. If necessary, have the brake repaired before operating the machine.
Pressurized air flows into inlet (6) through orifice (4). Air then flows through outlet (5). The air flows from outlet (5) to the parking brake chamber. The pressurized air holds valve assembly (8) in contact with exhaust (7). This prevents air from flowing out of the exhaust port. The parking brake is now released.The control valve (parking brake) will activate automatically when the air pressure lowers below a specific pressure. At this pressure or less, spring (3) moves valve (8) upward to the out position. Valve (8) comes into contact with valve body (2). The parking brake is engaged. Refer to Specifications, "Control Valve (Parking Brake)" for pressure settings.