DRUM GP-COMPACTOR 2287820 - Caterpillar

Secondary and Parking Brake Valve
The secondary and parking brake valve is located behind the operators station on the left side of the vehicle close to the accumulator manifold.
Secondary and Parking Brake Valve
1. Secondary Brake Solenoid Valve 2. Parking Brake Solenoid Valve 3. Pressure Reducing Valve (Secondary) 4. Pressure Reducing Valve (Parking) 5. Pressure Switch (Parking Brake Engaged)The valve is a cartridge type, incorporating two solenoid valves, two pressure reducing valves and a shuttle (resolver) valve.The shuttle (resolver) valve, one pressure reducing valve and one solenoid valve are used to control the secondary braking system.The remaining pressure reducing valve and solenoid valve are used to control the flow of oil to the parking brake.A check valve is located in the accumulator manifold. This check valve prevents the reverse flow of oil when the brakes / suspension pump is not running and so ensures that the parking brake can be engaged and released a number of times.All valve ports are clearly marked with a number which identifies the function of that port.Port "T1" is the return port to the hydraulic tank.Port "C1" is the supply port to the parking brake.Port "C2" is the supply port to the front axle brakes.Port "P2" is the inlet port from the accumulator manifold.Port "P3" is the inlet port from the service brake valve.Port "S1" Pressure switch port (Parking brake engaged)Parking Brake
The parking brake comprises two spring engaged, hydraulic pressure released, dry disc brake calipers acting on a single brake disc mounted into the transmission drive shaft.
Parking Brake
1. Cavity 2. Piston 3. Spring 4. Brake Lining 5. Brake DiscWhen the parking brake control is in the disengaged position, oil is directed into the cavity (1) behind the piston (2). This moves the piston and compresses the spring (3) moving the brake lining (4) away from the brake disc (5) which is then free to rotate and the brake is disengaged.When the parking brake control is in the engaged position, oil pressure in the cavity (1) is relieved to tank, allowing the spring (3) to expand and move the piston (2) and brake lining (4) onto the brake disc (5) preventing it from rotating. The brake is now engaged.Service Brake Groups
The service brake groups are disc type units.The D350E center axle and rear axle, and the D400E rear axle have one caliper to each disc.The D400E front axle and center axle, and the D350E front axle have two calipers to each disc.
Service Brake Group
1. Gallery 2. Pistons (three each side) 3. Lining Assemblies 4. Brake Disc 5. GalleryWhen the service brake valve is activated, oil under pressure is fed to galleries (1) and (5). This oil forces pistons (2) inward which move lining assemblies (3) into contact with disc (4).Accumulators
The accumulators are located behind the operators station on the left side of the vehicle.
Location of Accumulators 1. Front Axle and Parking Brake Accumulator2. Center and Rear Axle Brake Accumulator3. Low Brake Pressure Warning SwitchThe accumulators are rubber diaphragm type units which cannot be repaired. If any