This section discusses the features and operation of the brake system. The following motor graders are covered in this section:
- 12M Series 3
- 140M Series 3
- 160M Series 3
The brake system has the following main components:
- Monitoring system
- Piston pump (brake and hydraulic fan)
- Pump control valve
- Control manifold
- Brake accumulator
- Service brake control
- Wheel group
- Parking brake
- Parking brake solenoid
- Oil cooler (brake and hydraulic fan)
The AVSpare Monitoring System consists of an action alarm, action light, and a monitoring panel. The monitoring panel contains individual alert indicators for each machine system and two LCD display screens. The AVSpare Monitoring System provides three warning categories. The first warning category requires only operator awareness. The second warning category needs operator response. The third warning category requires immediate shutdown of the machine systems.
The brake pump is a variable displacement axial piston pump. The piston pump also services the hydraulic fan giving priority to the brake system. When the engine is operating, the pump will rotate in a counter clockwise direction producing flow to satisfy the following conditions:
- The demand of the brake system
- The demand of the hydraulic fan system
The pump will produce flow until the following conditions are met:
- The pressure setting of the pressure compensator is reached.
- The brakes and the hydraulic fan are not being operated.
The pump control valve is mounted on the piston pump (brake and hydraulic fan). The pump control valve has two functions. The pump control valve controls system pressure. The pump control valve is load sensing. The piston pump (brake and hydraulic fan) will only produce enough oil flow to satisfy the demand of the brake and the hydraulic fan system.
The control manifold directs the oil from the brake and the hydraulic fan pump to the brake circuit and to the fan circuit.
There are two brake accumulators in the brake system. The brake accumulators maintain brake system pressure when the brake and hydraulic fan pump is destroked.
The service brake control valve for the service brakes provides the proper flow in order to engage the service brakes. The service brake control for the service brakes also balances the oil pressure between the left side brakes and the right side brakes.
The service brakes are located in the wheel groups. The service brakes are actuated by oil pressure from the service brake control valve for the service brakes. The service brakes are activated when the brake pedal is depressed.
Refer to the Power Train Systems Operation/Testing and Adjusting for information regarding the parking brake and parking brake components for your machine.
The oil cooler (brake and hydraulic fan) is located behind the radiator group. Oil flows from the gear motor (hydraulic fan) through the cooler. The oil flows through the return filter and into the hydraulic tank.