Bosch Rexroth AB, RE 15328/06.2021
24 Hägglunds SP 40 to SP 180 | Axial piston pump
Boost pump and valve technology
(see Fig. 34 for position references)
Boost pump (Pos. 9)
Sizes see Table 1
Control pressure relief valve (for EP and HD) (Pos. 8)
Direct operated, high-pressure-related relief.
At low working pressure, the auxiliary pump pressure is
regulated to the set value (e.g. 32bar). This pressure is
needed by the HD and EP controls to swivel out reliably.
Using this valve saves the use of a separate control pres-
sure pump.
If the working pressure exceeds the pressure of the boost
pump, control is provided by the check valve via the high
pressure. At the same time, the increase in working pres-
sure relieves the control pressure relief valve.
The boost pump pressure is hereby reduced to the set
boost pressure (e.g. 15bar).
This function leads to energy savings, improved efciency
and a longer service life of the auxiliary pump.
For setting values, see Table 6.
Flushing valve (Pos. 4)
To open the ushing valve safely, the pressure differential
between A and B is required, as shown in Fig. 33. The
required pressure at 1500 rpm. The circuit temperature
needs to be monitored to avoid any damage to the system.
Pressure compensator valve (Pos. 2)
The SP pump has one common integrated pressure
compensator relief valve (2) for both sides, A and B.
For different pressure setting between the sides, two
external pressure relief valves must be added. The valves
are connected to XA2 (A-port compensator setting) and
XB2 (B-port compensator setting). The external valves
must be drained to tank.
Observe that relief valve (2) must be set on a higher
pressure level than the two external relief valves.
These relief valves must be ordered separately and must
be installed on site. (They are not mounted on the pump)
(Spare part pump). If pump is in a new manufacturing of
a drive unit then these will of course be mounted in the
drive unit.
Standard value that is set on pressure compensation is
350 bar, if other value is needed add a comment when
ordering the pump.
High-pressure relief valve (Pos. 5)
Two pilot-operated pressure relief valves use pressure
limitation to prevent damage to the hydraulic pump result-
ing from overpressure. A pressure relief valve is assigned
to each pressure side.
Protection is provided by reducing the high pressure to
the low pressure side.
The pressure limitation is set by default to pressure com-
pensator (2) + 40 bar, if another setting is required add
that as a comment when order the pump.
Boost pressure
To prevent damage to the system, low pressure monitoring
is recommended, which monitors the static pressure
component. Port M
K4
are suitable, also M
E3
can be used.
In this datasheet all values for charge pressure monitoring
are refered to M
K4
. For normal operations, 15bar (mea-
sured in M
K4
) charge pressure is set. For operation in
applications where dynamic pressure drops may occur.a
higher charge pressure value must be set.
The lowest allowed value is 8 bar (occuring during 2 sec-
onds).
For shock load applications use an accumulatior in K
4
.
Fig. 33: Cracking pressure differential for ushing valve
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4
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