Bosch Rexroth A7VO 63 Series Manual page 12

12 A7VO Series 63 | Axial piston variable pump
LR – Power controller without power override
LRDS – Power control with pressure cut-off and load
sensing
The load sensing controller works as a load-pressure con-
trolled flow controller and adjusts the displacement of the
pump to the volume required by the consumer. The flow of
the pump is then dependent on the cross section of the
external measuring orifice (1), which is located between
the pump and the consumer. Below the power curve and
the setting of the pressure cut-off and within the control
range of the pump, the flow is independent of the load
pressure.
The measuring orifice is usually a separately located load
sensing directional valve (control block). The position of
the directional valve spool determines the opening cross-
section of the measuring orifice and thus the flow of the
pump.
The load sensing controller compares pressure before and
after the orifice and keeps the pressure drop (differential
pressure Δp) across the orifice – and therefore the
flow – constant.
If the differential pressure ∆p at the measuring orifice rises,
the pump is swiveled back (toward V
pressure Δp drops, the pump is swiveled out (toward
V ) until equilibrium at the measuring orifice is restored.
g max
Δp = p – p
measuring orifice pump
▶ Setting range for Δp 14 to 25 bar
▶ Default setting 18 bar
When ordering, state the setting in plain text.
The stand-by pressure in zero-stroke mode (metering orifice
closed) is slightly higher than the Δp setting.
In an LUDV system, the pressure cut-off is integrated in the
flow sharing control block (LUDV).
Bosch Rexroth AG, RE 92202/02.2015
). If the differential
g min
consumer
▼ Characteristic curve LRDS
max
350
200
min
V displacement
g min
▼ Schematic LRDS
U R
1
V
g min
V
g max
R
2
The measuring orifice (control block) (1) is not included in
the scope of delivery.
V
g max
X
4
B(A)
A
1
1
X
3
T
1
S
M
1