HARNESS GP-WIRING 4P2451 - Caterpillar

Illustration 1 g01098687
Typical Air Start System
(1) Relay valve
(2) Air start control valve
(3) Air start motor
(4) Oiler The air start motor (2) can be mounted on either side of the engine. Air is normally contained in a storage tank. The storage tank must hold this volume of air at 1720 kPa (250 psi) when the storage tank is filled.The regulator setting is approximately 690 kPa (100 psi) for engines which do not have heavy loads when the engine is started. This setting is a favorable compromise between the following conditions:
The engine cranking speeds that are needed to start the engine
Volume of air in the storage tankIf the engine has a heavy load which can not be disconnected during starting, the setting of the air pressure regulating valve needs to be higher in order to get high enough speed for easy starting.This system is designed to operate between 640 kPa (93 psi) and 1034 kPa (150 psi). A pressure regulator must be used for pressures above 1034 kPa (150 psi).The air consumption is directly related to speed. Also, the air pressure is related to the force that is needed to turn the engine flywheel. If necessary, the air pressure regulator can be adjusted to 1034 kPa (150 psi) in order to produce the correct cranking speed for a heavily loaded engine. With the correct setting, the air start motor can turn the excessively loaded engine as fast as an engine that does not have an excessive load.Other air supplies can be used with the correct pressure and volume. For good life of the air start motor, the supply should be free of dirt and water. The maximum pressure for use in the air start motor is 1030 kPa (150 psi).
Illustration 2 g01098688
Air Start Motor
(5) Air inlet
(6) Vanes
(7) Rotor
(8) Pinion
(9) Gears
(10) Piston
(11) Piston spring The air from the supply goes to relay valve (3). The air start control valve (1) is connected to the line before the relay valve. The flow of air is stopped by the relay valve until air start control valve (1) is activated. Then, air from the control valve goes to piston (10) and behind pinion (8) for the air start motor. The air pressure on piston (10) compresses piston spring (11). Also, the air pressure on piston (10) engages pinion (8) with the flywheel gear. When the pinion is in engagement, air can go out through another line to the relay valve. The air activates the relay valve which opens the supply line to the air start motor.The flow of air goes through the oiler (4) in order to pick up lubrication oil for the air start motor.The air with lubrication goes into the air start motor through air inlet (5). The pressure of the air pushes vanes (6) in rotor (7). This turns the rotor which is connected by gears (9) and a drive shaft to starter pinion (8) which turns the engine flywheel.When the engine starts running, the flywheel will start to turn faster than pinion