System Operation - Komatsu 730E Operation & Maintenance Manual

Maintenance - Section 4
Page 4- 16
Injectors (11, Figure 3-2)
Each injector delivers a controlled amount of pressur-
ized lubricant to a designated lube point. Refer to Figure
3-2 for locations.
Pressure Switch (27, Figure 3-2)
This pressure switch will activate a Lube System Low
Pressure Warning lamp on the overhead display if ade-
quate grease pressure (2000 psi (13790 kPa)) is not
attained within 1 minute. (Note: Warning system is
optional on early model trucks.)

SYSTEM OPERATION

Refer to Figure 3-3 & 3-4:
1. During truck operation, with the pump and timer
systems in a rest state, a preset time interval oc-
curs.
2. The lubrication cycle timer (1, Figure 3-4) provides
a 24 VDC signal through the normally closed relay
(3) used to energize the pump solenoid valve (4),
allowing hydraulic oil provided by the truck steering
pump circuit to flow to the pump motor and initiate
a pumping cycle.
3. The hydraulic oil pressure from the steering circuit
is reduced to 325 to 350 psi (2 240 to 2 413 kPa)
by the pressure reducing valve (4, Figure 3-3)
before entering the motor. In addition, the amount
of oil supplied to the pump is limited by the flow
control valve (6). Pump pressure can be read using
the gauge (5) mounted on the manifold.
1. Hydraulic Oil Return
2. Hydraulic Oil Supply
3. Pump Solenoid Valve
4. Pressure Reducing Valve
5. Motor Pressure Gauge
4. With oil flowing into the hydraulic motor, the grease
pump will operate, pumping grease from the reser-
voir to the injectors (13), and to the vent valve (11)
and the normally open pressure switch (9).
5. During this period, the injectors will meter the ap-
propriate amount of grease to each lubrication
point.
6. When grease pressure reaches the pressure switch
setting, the switch contacts will close and energize
the relay (3, Figure 3-4), removing power from the
hydraulic motor/pump solenoid and the the pump
will stop. The relay will remain energized until
grease pressure drops and the pressure switch
opens again or until the timer turns off.
7. After the pump solenoid valve (3) is de-energized,
hydraulic pressure in the manifold drops and the
vent valve will open, releasing grease pressure in
the lines to the injector banks. When this occurs,
the injectors are then able to recharge for the next
lubrication cycle.
8. The unloader valve (10) prevents excessive grease
pressure if the pressure switch fails to close and
shut off the hydraulic supply to the pump. The
unloader will open at approximately 4000 psi (27.6
MPa).
FIGURE 3-3. HYDRAULIC SCHEMATIC
6. Flow Control Valve
7. Hydraulic Motor
8. Grease Pump
9. Pressure Switch (N.O.)
OM4035.2 02/03
Automatic Lube System
10. Unloader Valve
11. Vent Valve
12. Orifice
13. Injector Bank