Maintenance - Section 42 06/06 0M4206 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 27,600 kPa (4000 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 13789 kPa (2000 psi). This switch mon- itors grease pressure in the injector bank on the rear axle housing. If the proper pressure is not sensed within 60 seconds and the switch contacts do not close, a warning light notifies the operator a problem exists in the lubrication 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 Pressure gauge (18, Figure 42-3) monitors hydraulic oil pressure to the inlet of the hydraulic motor. Time Delay Module 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 13789 kPa (2000 psi) within this period of time, the timer will apply 24VDC to sev- eral relays, which will illuminate the low pressure 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 20685 kPa (3000 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.