Operation 4000 SRM 660
1. LIFT C
YLINDER (2)
2. OUTER WELDMENT
3. INNER WELDMENT
4. CHAIN
SHEAVE
5. LIFT CHAIN (2)
6. CARRIAGE
7. BREATH
ER LINE
8. EXTERNAL LOWERING CONTROL VALVE
9. FROM MAIN CONTROL VALVE
10. TO HYDR
AULIC TANK
Figure
1. Mast Operation
CONTROL VALVE,
CARRIAGE/ATTACHMENT
The hydraulic functions for the carriage and attach-
ment are controlled by the auxiliary control valve.
The operator actuates the auxiliary control valve
with switches in the operator’s compartment. The oil
from the auxiliary control valve is used to move the
auxiliary spool in the main control valve. Oil from
the auxiliary spool flows to the selector valves for the
functions at the carriage, such as fork positioners.
When the operator pushes a switch, one solenoid on
the auxiliary control valve and a solenoid on the se-
lector valve are energized at the same time. The so-
lenoid on the auxiliary control valve opens and lets
oil flow through the pilot line to move the auxiliary
spool. The opposite end of the auxiliary spool is open
to drain through the other solenoid on the auxiliary
control valve. When the auxiliary spool moves, it lets
oil from the hydraulic pump flow to the selector valve
as required.
SELECTOR VALVE
A selector valve opens and closes a hydraulic circuit
for one function. See Figure 2. Each valve has one
solenoid that operates one spool. Selector valves are
mounted on a common hydraulic manifold on the car-
riage. The control valve for the carriage and attach-
ment starts and stops the flow of oil to the manifold.
A selector valve lets the oil flow to the cylinder or
cylinders for a specific function. The operator con-
trols the selector valves with separate switches for
each of the hydraulic functions. Each of the switches
operates the control valve and a selector valve at the
same time.
2
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