Counterbalance Valves - Manitowoc Grove CD3340B Service Manual

HYDRAULIC SYSTEM
Table 4-8
Function
Port
(Under High Pressure)
A Left Front Outrigger Up
B Left Front Outrigger Down
C Left Front Outrigger In
D Left Front Outrigger Out
E Right Front Outrigger In
F Right Front Outrigger Out
G Right Front Outrigger Up
H Right Front Outrigger Down
I Left Rear Outrigger Down
J Left Rear Outrigger Up
K Left Rear Outrigger In
L Left Rear Outrigger Out
M Right Rear Outrigger In
N Right Rear Outrigger Out
O Right Rear Outrigger Down
P Right Rear Outrigger Up
a0663
4-28

Counterbalance Valves

The vertical (jack) outrigger cylinders have load-holding
Sol. Wire
(counterbalance) valves installed in the base of the cylinder.
The purpose of these valves is to inhibit the cylinder from
A J21
retracting if a hydraulic hose breaks. The counterbalance
B J4
valve will hold the oil in the base of the cylinder until there is
A J17
sufficient oil and pressure from the pump available to the rod
side of the cylinder.
B J24
A J15
Oil flows freely through the counterbalance valve and into
the cylinder base end when the cylinder is being extended.
B J25
To retract the cylinder, oil is sent to the rod port of the
A J34
cylinder. As the cylinder starts to retract, the piston meets
B J3
resistance from the oil held in the cylinder base end by the
counterbalance valve. Pressure increases as the pump tries
A J20
to overcome the resistance.
B J10
A J32
B J1
A J31
B J18
A J14
B J33
Published 04/07/2015 Control # 569-00
CD3340B/YB4411
FIGURE 4-15