Variable Flow Pumps
Shuttle Valve Signal Network - Testing
The shuttle network can be easily checked. Start the engine
and operate the hydraulic system until the oil is at working
temperature.
With the engine at 1500 revs/min operate each service in the
following order:
1 Bucket
2 Dipper
3 Right Stabiliser
4 Left Stabiliser
5 Boom
6 Slew
7 Extradig
8 Lift
9 Shovel
10 Auxiliary
11 Steering
Note: If your machine is not equipped with these valve
sections, start with the furthest section from the pump and
work back to the nearest section.
If one valve section function either fails to work or is slow to
work in either one or both directions, the primary shuttle in
that section may be at fault.
If two or more valve sections next to each other fail to
operate correctly, check the secondary shuttles. To check
the secondary shuttle operate each service in sequence, the
last correctly functioning service nearest the pump may have
a secondary shuttle in that section at fault.
When a shuttle is suspected of malfunctioning, do the
following check:
Stall any control valve that is near the pump than the
suspected control valve. This should stall the entire system.
While at stall operate the malfunctioning valve section, if the
section operates correctly the shuttle in question is at fault.
If section still malfunctions the shuttle is NOT at fault.
Shuttles may be removed, check the seals and the shuttle
ball. Clean and refit or fit a new shuttle as required.
22 - 8
Section E
Hydraulics
9803/3280
Section E
22 - 8
Issue 1
Service Procedures
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