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6
BVD/BVE Series 52 | Counterbalance valve
Functional description
Functional description
Counterbalance valves are designed to reduce the danger of
overspeed and cavitation of axial piston motors in open cir-
cuits. Cavitation occurs if, during braking or load-lowering, the
rotational speed of the motor is greater than it should be for
the given inlet flow, causing the supply pressure to fall
sharply. If the supply pressure drops below the given value
∆p
, the counterbalance spool will move towards the close
K E
position. The cross-sectional area in the counterbalance valve
return channel is then reduced, creating a bottleneck in the
return flow of the hydraulic fluid. The pressure increases and
brakes the motor until the rotational speed of the motor
reaches the specified value for the given inlet flow.
The counterbalance valve is available in two versions.
BVD: Throttling effect in both flow directions, e.g. for moving
forward and backward
BVE: Throttling effect in one flow direction, e.g. for lowering
with pulling loads
See BVE circuit diagram on page 7
Bosch Rexroth AG, RE 95528/05.2016
Brake release
Version S
Counterbalance valve with shuttle valve and port G
(plugged), without brake release valve (pressure reduction).
The respective high pressure is balanced via the shuttle
valve and is available at port G
holding brake. The brake vent function without pressure
reduction via the brake release valve is only employed if the
mechanical holding brake is approved for the maximum
working pressure.
▼ Circuit diagram BVD...S
M
KD
D
2
G´
D´
Motor side
L´
C´
D
2
M
KC
Version L
Counterbalance valve with shuttle valve, brake release valve
for pressure reduction and port Br (plugged).
The respective high pressure is balanced and fed to the
brake release valve (pressure reducing valve) via the shuttle
valve. This opens from approx. 10 bar and reduces the
respective working pressure to approx. 21
vent function is employed when the mechanical brake on the
gear unit cannot handle the full system pressure.
The maximum permissible brake release pressure must be
agreed with the winch or track drive manufacturer.
ext
for venting the mechanical
ext
D
1
D
Port side (on
the pump side)
G
ext
Counterbalance
spool
C
D
1
+4
bar. This brake
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