RE 92202
/02.2015,
Bosch Rexroth AG
Axial piston variable pump |
A7VO Series 63
Shaft seal ring
5
Filtration of the hydraulic fluid
Finer filtration improves the cleanliness level of the hydrau-
lic fluid, which in turn increases the service life of the axial
piston unit.
A cleanliness level of at least 20/18/15 is to be maintained
according to ISO 4406.
At very high hydraulic fluid temperatures (90 °C to maxi-
mum 103 °C, measured at port
R
1
/
R
2
) a cleanliness level is
necessary of at least 19/17/14 according to ISO 4406.
Leakage
The case interior is connected to the suction chamber. A
separate case drain line from the case to the reservoir is
therefore not required (both
R
ports are plugged).
Exception: For versions with pressure controller or pressure
cut-off, a drain line is needed to relieve port
T
1
to the
reservoir.
Shaft seal ring
Permissible pressure loading
The service life of the shaft seal is influenced by the speed
of the axial piston unit and the leakage pressure in the
housing (case pressure). Momentary pressure spikes
(
t
< 0.1 s) up to 10 bar are allowed. The service life of the
shaft seal decreases with increasing frequency of pressure
spikes and increasing mean differential pressure.
The case pressure must be equal to or higher than the
ambient pressure.
0
1
2
3
4
5
2000
0
4000
6000
Differ
ential pr
es
sur
e
∆p
[bar]
Rotational speed
n
[rpm]
NG107
NG160
NG28
NG55
NG80
The FKM shaft seal ring may be used for leakage
temperatures from -25 °C to +115 °C. For application cases
below -25 °C, an NBR shaft seal is required (permissible
temperature range: -40 °C to +90 °C).
Flow direction
Direction of rotation, viewed on drive shaft
clockwise
counter-clockwise
S
to
B
S
to
A