Maintenance - Section 42 07/09 0M4211 Page 42-4 Automatic Lubrication System Solenoid Valve Solenoid valve (19), when energized, allows oil to flow to the hydraulic motor. Unloader Valve Unloader valve (20) is mounted on a tee fitting with pump cutoff pressure switch (21). This valve will relieve grease pressure in the pump if pressure exceeds 27 580 kPa (4,000 psi). This valve has been factory adjusted and is not repairable. Vent Valve With vent valve (1, Figure 42-3) closed, the pump continues to operate until maximum grease pressure is achieved. As this occurs, the vent valve opens and allows the grease pressure to drop to zero, so the injectors can recharge for their next output cycle.
Pressure Switch Pressure switch (15, Figure 42-4) is a normally open switch set at 13 790 kPa (2,000 psi). This switch monitors grease pressure in the injector bank on the rear axle housing. If the appropriate grease pressure is not achieved during the normal pump cycle, the warning system will be activated, turning on warning light to notify operator a problem exists in the lubrica- tion system. 24VDC Lubrication Cycle Timer Lubrication cycle timer (2, Figure 42-11) provides a 24VDC timed-interval signal to operate solenoid valve (19, Figure 42-3), causing the grease pump motor to operate. This timer is mounted in the cab interface compartment.
Pressure Gauge Time Delay Module Pressure gauge (18, Figure 42-3) monitors hydraulic oil pressure to the inlet of the hydraulic motor. Time delay module (7, Figure 42-6), located in the electrical interface cabinet, provides a one minute delay in the low pressure warning light circuit to allow a normally operating system to attain full grease sys- tem pressure without activating the warning light. If the system fails to reach 13 790 kPa (2,000 psi) within this period of time, the timer will apply 24VDC to several relays, which will illuminate the low pres- sure warning light in the overhead panel. An external 604K ohm resistor determines the delay period.
Manual Override Button Manual override button (17, Figure 42-3) is used to actuate the hydraulic motor to manually activate a lubrication cycle. Injectors Injectors deliver a controlled amount of pressurized lubricant to a designated lubrication point. Refer to Figure 42-3 and 42-4 for the locations of each lubri- cated component. Pump Cutoff Pressure Switch Pump cutoff pressure switch (21, Figure 42-3) is a normally open switch set at 20 685 kPa (3,000 psi). This switch de-energizes the pump solenoid relay when the grease line pressure reaches the switch pressure setting, turning off the motor and pump.