10
Parker Hannifin Manufacturing Germany GmbH & Co. KG
Pump & Motor Division Europe
Chemnitz, Germany
Electro hydraulic proportional controls version 45 for
axial piston pumps, PV series
Bulletin MSG30-3254-INST/UK
Installation and setup manual
As already mentioned in chapter 1, a propor-
tional controlled variable displacement pump
needs always a minimum outlet pressure of ap-
prox. 20bar, to down stroke the pump against
the servo spring force.
In some applications and especially at small
displacement settings that is not always given.
Two possibilities to solve this issue are de-
scribed in the following chapters:
If and external auxiliary pressure is available, this
can be used to control the pump at low outlet
pressure. This method is explained in chapter 6.
The other option is the use of a preload valve
(sequence valve).
Figure 8 is showing the hydraulic circuit of a
pump with ...UPR control, using a preload valve.
The preload valve is oered as a manifold, that
can directly be flanged to the pressure port of
the pump. The ordering code is PVAPVV*. The *
stands for the frame size of the pump, the screw
option and the seal material.
The preload valve is also available as slip in car-
tridge valve according to DIN 24 342.
Because of the pilot valve characteristic the
opening pressure p1 is approx. 20 bar. The port
Mp1 can be used to get under all working con-
ditions a pressure of 20 bar e.g. to pilot valves
with external pilot pressure supply. At approx.
25 bar system pressure the valve is fully open
(pressure drop < 1 bar).
S T
M
P1
AP
T
AP
T
S
U
M
WV
B
D2
A
P TAP
P
T
P
M
p1
p
P
p2
M
p1
X
Q
X
P
I
P
I
Q:A
I
Q:B
W
Q
W
P
preload valve,
Code PVAPVV*
B
P
P
T
T
X
Q
= signal, displacement
I
Q:A
= solenoid current A, displacement control valve
I
Q:B
= solenoid current B, displacement control valve
X
P
= signal, pressure sensor
I
P
= solenoid current, pressure pilot Valve
W
Q
= command, displacement
W
P
= command, pressure
5. Preload valve for proportional controlled pumps, code PVAPVV...
Figure 8: Hydraulic circuit of a pump with ...UDK with preload valve control
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