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| Illustration 1 | g00663689 |
Brake Lines and Brake Cooling Lines | |
The final drive units for the front axle and for the center axle contain oil cooled multi-disc brakes. The oil cooled multi-disc brakes are the service brakes for the machine. When the service brake control (pedal) is pressed, oil pressure engages the service brakes.
The oil cooled multi-disc brakes that are on the front axle also provide secondary brakes for the machine.
The parking brake is located on the rear chassis behind the oscillating hitch.
Service Brakes
When the service brake pedal is pressed, pressurized oil engages the service brakes in order to reduce machine speed.
Oil flows from the piston pump through the check and pressure reducing valve to the service brake control valve. Oil also flows from the piston pump to the another service brake system valve (ASBS valve).
When the service brake pedal is pressed oil flows through the service brake control valve to the ASBS valve. The ASBS valve sends this oil to the slack adjuster for the front axle brakes. Also when the service brake pedal is pressed oil flows through the service brake control valve to the slack adjuster for the center axle brakes. The slack adjuster for the front axle brakes sends pressurized oil to the front axle brakes. The slack adjuster for the center axle brakes sends pressurized oil to the center axle brakes.
Oil that flows to the service brake control valve flows to the accumulators. One accumulator is for the front axle brakes. The other accumulator is for the center axle brakes. The accumulators act as a source of stored energy in order to assist in the rapid application of the service brakes. The accumulators also allow the service brakes to be engaged several times if there is a loss of system pressure from the piston pump.
Secondary Brakes
The secondary brakes are used to slow the machine and the secondary brakes are used to stop the machine if there is a failure of the service brake system. The secondary brakes are also used to hold the machine stationary when the engine is running.
The secondary brakes operate when the engine is running and when the parking and secondary brake control is in the ENGAGED position. The parking brake is not engaged. The piston pump sends pressurized oil to the ASBS valve. The Power Train Electronic Control Module activates a solenoid valve within the ASBS valve. The solenoid valve allows pressurized oil to flow to the slack adjuster for the front axle brakes.
The slack adjuster for the front axle brakes sends pressurized oil to the front axle brakes.
Parking Brake
The parking brake is used to hold the machine stationary when the engine is stopped. The parking and secondary brake control must be in the ENGAGED position.
The main components of the parking brake are a disc and a caliper. The disc is mounted in the drive line and the caliper is mounted on the rear chassis. The parking brake is engaged by spring force and disengaged by oil pressure.
The piston pump provides pressurized oil to the ASBS valve. When the engine is running, a solenoid valve within the ASBS valve is activated. This allows pressurized oil to flow to the parking brake. The parking brake is disengaged.
The parking brake accumulator provides a source of stored energy in order to disengage the parking brake if there is no pressure in the supply line.
The parking brake is used to reduce machine speed if the pressure switch in the supply line to the front service brake does not sense oil pressure and the parking and secondary control (switch) has been moved to the engaged position.
The parking brake will automatically engage when you turn off the engine.
Service Brake Cooling
Oil flows from the hoist control valve through the relief valve and the oil cooler in order to cool the oil before the oil is used to cool the discs in the service brake. The relief valve protects the oil cooler from excess pressure.
A manifold distributes the cooled oil as well as controlling the flow of cooled oil to the service brakes. The oil returns to the tank after the discs in the service brakes have been cooled. If the hoist control valve is in the LOWER position cooled oil does not flow to the service brake.