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9. If using the LT5, LT10 or LT20 positive displacement flow blocks as remote input to
measure case drain leakage, it is recommended that a relief valve or check valve 1 bar (15
psi) is fitted in a tee to protect the pump or motor against excessive pressure in the event
of a surge flow. Consult Sales Office for further information on Tee fittings.
10. An additional gauge may be connected to the tester block using a pressure test point and
micro bore hose. See page 4 for details. Note: Always disconnect the low pressure gauge
for high pressure testing if it is not protected by an automatic cut-out valve.
Trouble Shooting with the Hydraulic Tester
PRELIMINARY: Check oil level in tank, pump drive, valve linkage for damaged parts, external
oil leaks etc
Problem
Excessive pump noise
fluctuating pressure
Low flow under no load
Decreasing performance
as pressure increases on
all circuits
On one circuit
Fails to hold load
The standard Webtec Hydraulic Testers are designed for use with mineral oil having reasonable
lubrication properties. They are not suitable for use with water or fluids with a high water
content. If a tester is used with water it should be flushed immediately after use with white or
methylated spirit or similar and then flushed with mineral oil to minimise any internal corrosion.
This may avoid an expensive repair. Damage to a tester from the use of a non-approved fluid
invalidates our normal warranty.
Possible Cause
Pump cavitation caused by:
a) Clogged suction filter
b) Restricted suction line
c) Air leak in pump suction line,
fittings, shaft seals etc.
d) Pump speed too high
Internal leakage in:
a) Pump
b) Main Relief Valve
c) Directional Control Valve
d) Cylinder or Hydraulic Motor
Directional Control Valve
Cross line Relief Valve
Cylinder
Do not use with Water
2
Suggested Test,
See Paragraph:
3.0; 4.1
3.0; 4.1
4.2; 4.3
4.2; 4.3; 4.4; 5.0
5.1; 5.2
4.2; 4.3; 4.4; 5.0
5.02
5.0; 5.2
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