HARBEN 4018 US Van Pack, Operation & Maintenance Manual

Page: 32 / 48

31
6.2. Fault Finding - Hydraulic
Problem Possible Cause
Recommended
Action
Low system
pressure

Worn or incorrect size of
cutting nozzle

Engine speed slow

Leaks from hose, pipes,
and connections

Blocked inlet filter

Inlet hose to long

Loss of water through dump
line of selector valve or gun
when high-pressure
selected

Loss of water through dump
line of remote-control kit, if
fitted

Replace the old jetting
Nozzle with a new one

Adjust to correct speed

Check the connections for
tightness, replace if
needed

Clean or replace element

Shorten hose length

Check seats and seals

Check seats and seals
High system
pressure

Blocked nozzle, selector
valve or gun

Incorrect nozzle size

Incorrect bore size

Engine speed high

Crushed delivery hose

Two-gun choke left in gun
when operating as single
gun unit

Clean the items and flush
out the delivery line

Replace the nozzle

Replace the hose

Adjust to correct speed

Replace if necessary

Replace with standard
choke
Low water level

Blocked or dirty pre-filters

Faulty ball valve assembly

Wrong seat in ball valve
assembly

Low inlet pressure

Clean or replace elements

Replace if necessary

Replace the seat if
necessary

Increase pressure
Pump not
running evenly
(also refer to
pump faults) 
Air in water

Air in crankcase oil

Worn drive coupling

Faulty inlet or delivery valve

Valve nut over tightened

Water bleed pump

Oil bleed pump

Replace flexible elements
and examine coupling

Check valve condition

Check tightness of inlet &
delivery nut
Burst disc failure
or safety relief
valve operating
(also refer to
high system
pressure
problem)

Incorrect burst disc

Incorrect valve setting

Faulty valve

Faulty or fatigued burst disc

Replace with correct disc

Check certificate/setting

Repair or replace if
required

Replace with new disc