WEBTEC DHC 51 Operating Manual page 3

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
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
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