Manitowoc Grove 5540F Service Manual

GROVE Published 10-21-2010, Control# 198-04 4-31
5540F/YB5515 SERVICE MANUAL HYDRAULIC SYSTEM
4
System Function
The main control valve sections for the hoist, telescope and
lift functions each have a check valve installed internally.
This check valve is connected to the return passage in the
valve section and to port A (boom lift and telescope) or port B
(Winch) of the valve section. Its primary function is to release
hydraulic oil back to tank whenever the anti-double block
solenoid valves are open (de-energized).
During normal operation the solenoid valves are in the
closed (energized) position Figure 4-34. In the closed
position oil under pressure is stopped by the solenoid valve
from returning to tank. The blocked fluid under pressure
passes through a restriction in the valve section to the check
valve. The check valve is held closed by a combination of the
check valve spring and oil pressure from the closed solenoid
valve. In combination, the oil pressure and spring pressure is
greater than the return oil pressure and the check valve is
kept closed. Return oil is then directed through the valve
spool to the outlet port of the control valve.
When the hoist block comes in contact with the anti-double
blocking bracket at the end of the boom head, the bracket
raises and actuates a switch. This switch, when actuated,
removes the electrical signal to the three solenoid valves
opening them Figure 4-35. With the solenoid valves open, oil
supply to the check valve is reduced. The check valve spring
alone is not enough to hold the check valve closed,
therefore, the check valve opens. With the check valve
opens, hydraulic oil which would normally flow to the lift
cylinder, telescopic cylinder or hoist motor through port A or
port B of the valve section is returned through the check
valve to the outlet of the control valve, or through the open
solenoid valve, back to tank.
Lowering the hoist block will deactivate the switch to close
the solenoid valves and return flow through port A or port B
to the function.
FIGURE 4-32
p1873
p1622
Anti-Double Block Bracket
Anti-Double
Blocking
Solenoids
Valve Location
FIGURE 4-33
p1874
Reference Only

Manitowoc Grove 5540F Specifications

General

Brand	Manitowoc
Model	Grove 5540F
Category	Construction Equipment
Language	English