CRANKSHAFT GP 1169988 - Caterpillar

DISC BRAKE ASSEMBLY
1. Head assembly. 2. Anchor pin. 3. Friction pad. 4. Metal backing. 5. Piston. 6. Disc.Head Assembly
HEAD ASSEMBLY (CALIPER)
1. Anchor retaining bolt. 2. Metal backing. 3. Friction pad. 4. Anchor pin. 5. Bleed valves. 6. Piston and seal. 7. Head assembly.Oil flow to the brakes is through lines and drilled passages to all pistons within each head assembly.When an application of the brakes is made, the hydraulic pressure is made the same (balances) the pistons and the force on each side of the disc is the same. The pistons do not have return springs.To make a pad replacement the caliper need not be removed. For replacement of pads, remove the anchor pin and slide the pad out.
Do not make a brake application with pads removed. The pistons must not be permitted to extend out of their bores as the pads are removed. Open the bleed valves on the caliper to release any pressure on the piston. If the pistons extend and let the seals come out, caliper removal will be needed to install the pistons.
Two bleed valves on each caliper are used to let air out of the hydraulic brake system. Let air out of the brakes (bleed) whenever a line is disconnected in the hydraulic brake circuit.Parking Brake
PARKING BRAKEPull on the knob for the parking brake control valve to open the valve and activate the parking brake. Push on the knob to release the parking brake. Air pressure in the line to parking brake control valve must be 50 psi (345 kPa) minimum for the valve to stay closed.The parking brake activates automatically when the air pressure in the line to the parking brake control valve goes below 40 psi (280 kPa).
PARKING BRAKE CONTROL VALVEThe parking brake will not let the output shaft of the transmission turn when the air pressure to the brake chamber is below 40 5 psi (280 35 kPa). The brake drum with shoes inside is on the output shaft of the transmission.The brake chamber activates the shoes. The parking brake is activated by a spring and released by air pressure. Force of the spring moves the rod of the brake chamber and the brake lever is pulled UP by the rod to activate the brake. Air pressure works on the diaphragm to cause compression of the spring and extension of the rod. The rod pushes the brake lever DOWN to RELEASE the brake.Control Valve for Parking Brake
The control valve, which is on the dash, has control over the supply of air that goes to the chamber of the parking brake. With valve knob (1) pulled OUT, the line to the brake chamber is open to the atmosphere and causes the application of the brake. With valve knob (1) pushed IN, air goes from the reservoir into the chamber of the parking brake and releases the brake.
FLOW OF AIR; APPLICATION OF PARKING BRAKE
1. Knob and pin assembly. 2. Valve body. 3. Spring. 4. Orifice. 5. Outlet (to chamber of