DOWEL 8H5244 - Caterpillar

An air starting motor is used to turn the engine flywheel with enough rpm in order to start the engine. Operation of the air starting motor is controlled by the engine's control system. The air starting motor will engage when the requirements for prelube have been met.The air starting motor is usually mounted on the left side of the engine. Air is normally contained in a storage tank. The duration for rotation of the flywheel is determined by the tank's volume, air pressure, and air restriction.For starting the engines which do not have heavy loads, the air pressure is approximately 1034 kPa (150 psi). This pressure provides a good relationship between the duration of the flywheel's rotation and the cranking speed.Note: Minimum recommended cranking speed for start-up is 80 rpm. The fuel system and the ignition system are activated at engine speeds above 50 rpm. The maximum cranking speed of the air starting motor is 150 rpm.If the engine has a heavy load which cannot be disconnected during starting, the air pressure regulator must be adjusted in order to provide enough speed for easy starting.The air consumption is directly related to speed. The air pressure is related to the effort that is necessary in order to turn the engine flywheel. The maximum pressure for use in the air starting motor is 1723 kPa (250 psi). This will provide sufficient cranking speed for a heavily loaded engine. With the correct air pressure, the air starting motor can turn the heavily loaded engine at the same speed and for the same duration as the air starting motor can turn a lightly loaded engine.For good life of the air starting motor, ensure that the air supply is free of dirt and water. Use a lubricator with "SAE 10W" nondetergent oil for temperature above 0 °C (32 °F). Use air tool oil for temperatures below 0 °C (32 °F).