The D9R can also be equipped with an optional engine prelubrication starting system. A prelubrication starting system will prime the engine with oil before the starter begins to crank the engine. This system reduces engine component wear that usually occurs during start-up. The prelubrication starter is located on the left side of the engine toward the rear of the engine compartment.
Prelubrication of the engine is achieved by the use of a modified engine starter that is equipped with a gear-type pump. When the starter turns, the gear pump draws oil through a suction line from the engine sump and directs the flow through a one-way check valve into the lubrication system of the engine.
An oil pressure switch is located on the left side of the engine just above the starter. This oil pressure switch is used to send a signal to the prelubrication timer/solenoid when the oil pressure in the system reaches 28 kPa (4 psi).
To start the machine using the prelubrication system, the operator must turn the key start switch to the START position. The key start switch energizes the master relay and sends current to the prelubrication timer/solenoid through wire 307 OR.
As the operator holds the key start switch in the START position, the prelubrication timer/solenoid directs the current through wire 301 BU to the opposite end of the starter motor coil. This current closes the starter relay and connects a path for battery current to turn the starter motor.
However, the current does not energize the solenoid which engages the starter pinion with the engine flywheel.
The spinning starter motor drives the gear pump on the end of the motor. The gear pump draws oil from the engine oil sump and directs the oil into the lubrication system to prelubricate the engine. A check valve is located in the pressure line to prevent the back flow of oil from the engine after it is started and the engine oil pump starts to produce flow.
When the pressure in the oil galley increases to 28 kPa (4 psi), an oil pressure switch will open. This condition causes current to the starter motor to stop and the prelubrication timer/solenoid to pause for three seconds. This pause allows the starter motor to slow down before the pinion engages the engine flywheel.
After the pause time, the prelubrication timer/solenoid sends current through wire 337 WH which energizes the starter relay and the normal cycle for engine start-up. The starter motor pinion then engages the flywheel and the starter cranks the engine. When the engine starts, the operator releases the key start switch.