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Section E
22 - 6
Variable Flow Pumps
Regulator Valve Adjustment (Cont'd)
The load sense system is a dynamic type, which means a
small flow (0.22 t o 1.1 gall/ 1 t o 5 lit re p er minut e) is
circulated through the load sense line.
The flow is available due to a 0.02 in (0.6 mm) orifice in the
flow regulator spool in the pump control housing. This orifice
can be blocked or partially restricted which will give poor
performance, slow operating speed and/or low maximum
stall speed. If completely blocked, margin pressure and
stand-by pressure can be difficult to adjust and the loader
servic es may op erat e int ermit t ent ly even t hough t he
excavator operates correctly.
If any of the above symptoms are experienced carry out the
following:
1
Lower the backhoe bucket and loader shovel to rest
on the ground. Stop the engine and remove the
starter key.
2
Gain access to the regulator valve assembly.
3
Disconnect the load sense line at A. Attach a 0.25
inch (6.35 mm) hose to pump of suitable length to
route to a measuring container.
4
Start the engine and measure the flow which should
be at least 0.22 gall/1 litre per minute at 2200 RPM.
5
If the flow is below 0.22gall/1 litre per minute, remove
spool B and clean/unblock orifice C as required.
Fit spool B and check the flow as described at step 3
6
and 4.
7
If the flow is within limits check the stand-by pressure.
Refer to Flow and Pressure Testing.
9803/3280
Hydraulics
Service Procedures
Purchased from www.WorkshopManuals.co.uk
B
B
C
A
Section E
22 - 6
347850
Issue 1
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