OM4033.2 Maintenance - Section 4 Automatic Lubrication System 4-15 SYSTEM COMPONENTS With the vent valve 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 0, so the injectors can recharge for their next output cycle. Vent Valve (7, Figure 4-1) Filter (21, Figure 4-2) A filter assembly mounted on the grease reservoir fil- ters the grease prior to refilling the reservoir from the shop supply. A bypass indicator alerts service person- nel when the filter requires replacement.
Lubrication Cycle Timer (1, Figure 4-4) The rotary hydraulic pump is a fully hydraulically oper- ated grease pump. An integrated pump control mani- fold is incorporated with the motor to control input flow and pressure. Hydraulic Motor and Pump (3 & 9, Figure 4-1) The solid state lubrication cycle timer provides a 24 VDC timed-interval signal to energize the solenoid valve (5, Figure 4-1), providing oil flow to operate the grease pump motor. This timer is mounted in the Elec- trical Interface Cabinet. Note: The pump crankcase oil level must be maintained to the level of the pipe plug port. If necessary, refill with 10W-30 motor oil.
Delay Timer (7, Figure 4-4) The delay timer, located in the Electrical Interface Cab- inet, provides a one minute delay in the low pressure warning lamp circuit to allow a normally operating sys- tem to attain full grease system pressure without acti- vating the warning lamp. If the system fails to reach 2000 psi (13 789 kPa) within this time period, the timer will apply 24VDC to several relays which will illuminate the low pressure warning lamp in the overhead display. An external 604K ohm resistor determines the delay period. Hydraulic oil supply inlet pressure must not exceed 3000 psi (20 685 kPa).
Exceeding the rated pressure may result in damage to the system com- ponents and personal injury. Pump Cutoff Pressure Switch (N.O. 2500 psi [17 237 kPa]) (18, Figure 4-2) Grease Reservoir (12, Figure 4-1) This pressure switch de-energizes the pump solenoid relay when the grease line pressure reaches the switch pressure setting, turning off the motor and pump. The reservoir has an approximate capacity of 90 lbs. (41 kg) of grease. When the grease supply is replen- ished by filling the system at the service center, the grease is passed through the filter to remove contami- nants before it flows into the reservoir. Grease Pressure Failure Switch (N.O.
2000 psi [13 789 kPa]) (24, Figure 4-2) Pressure Reducing Valve (4, Figure 4-1) This pressure switch monitors grease pressure in the injector bank on the rear axle housing. If the proper pressure is not sensed within 60 seconds (switch con- tacts do not close), several relays energize, actuating a warning lamp circuit to notify the operator a problem exists in the lube system. The pressure reducing valve, located on the manifold reduces the hydraulic supply pressure (from the truck steering circuit) to a suitable operating pressure, [325- 350 psi (2 240-2 415 kPa)] for the hydraulic motor used to drive the lubricant pump.
Pressure Gauge (8, Figure 4-1) Flow Control Valve (10, Figure 4-1) The pressure gauge monitors hydraulic oil pressure to the inlet of the hydraulic motor. The flow control valve mounted on the manifold, con- trols the amount of oil flow to the hydraulic motor. The flow control valve has been factory adjusted and the setting should not be disturbed. Injectors (23, Figure 4-2) Each injector delivers a controlled amount of pressur- ized lubricant to a designated lube point. Refer to Fig- ure 4-2 for locations. Solenoid Valve (5, Figure 4-1) The solenoid valve, when energized, allows oil to flow to the hydraulic motor.