Variable Flow Pumps
Regulator Valve Adjustment
Note:
If a new regulator valve is fitted, or a valve stripped,
cleaned and rebuilt, then the pressure spool should be
backed off to a low pressure. This will prevent inadvertent
damage to the pump.
Flow Regulator Spool
The pressure in the pump out line (pressure test connector
B
) should be 20 bar (290 lbf/in
2
) greater than the pressure in
the load sense line (pressure test connector
A
). If not adjust
the regulator flow spool as described below:
1
Lower the backhoe bucket and loader shovel to rest on
the ground; stop the engine; operate the control levers
to vent residual hydraulic pressure.
2
Gain access to the regulator valve assembly (mounted
on the pump).
3
Remove cap
C
and loosen locknut
D
.
4
Turn adjusting screw
E
clockwise to increase pressure
setting and anti-clockwise to decrease setting.
5
Rep eat p ressure t est as d et ailed p reviously and
establish valve is set correctly.
6
Tighten locknut, refit cap.
Pressure Regulator Spool
As previously explained, there is no ‘main relief valve’ to
control the system pressure (the pump swashplate angle will
increase or decrease according to pressure demand).
However in situations of maximum hydraulic stall, i.e. ram full
travel, the pressure in the circuit will achieve the setting of
the pressure regulator spool. To adjust the setting:
1
Lower the backhoe bucket and loader shovel to rest on
the ground; stop the engine; operate the control levers
to vent residual hydraulic pressure.
2
Gain access to the regulator valve assembly (mounted
on the pump).
3
Remove cap
F
and loosen locknut
G
.
4
Turn adjusting screw
H
clockwise to increase pressure
setting and anti-clockwise to decrease setting.
5
Rep eat p ressure t est as d et ailed p reviously and
establish valve is set correctly.
6
Tighten locknut, refit cap.
22 - 5
Section E
9803/3280
Section E
22 - 5
Issue 1
Service Procedures
F
G
C
D
H
E
S273100
S273401
A
B
