Malfunctions And Their Causes - Pfeifer HIT Traduction Des Instructions D'utilisation Et D'installation

13. Malfunctions and their causes

Fault
Pumping operation needs unusually
little effort, the jack does not lift the
load.
The piston does not move despite
pumping movements.
Pumping operation needs lot of effort
even without a load; it is not possible
to extend to the full lifting height.
Load is not being held.
Pump does not generate pressure.
Loss of oil in the jack.
Jack does not retract.
CAUTION: Malfunctions may only be
remedied by correspondingly qualified
personnel (see chapter 12 Inspection and
maintenance).
HIT-Hydraulikheber 12/2019 / Änderungen vorbehalten!
12
Cause
Non-return valve between the
pump and the tank is leaky.
The jack is overloaded and the
pressure relief valve was activated.
Too little air in the tank.
Too little oil in the system.
Vacuum in tank.
Oil filler screw is open.
Oil filler screw no longer closes or
the valve seat is leaking, e.g. due
to contamination with oil.
Non-return valve no longer closes
or the valve seat is leaking due to
contamination with oil.
Sealing elements worn.
Overpressure in tank.
Remedial action
Carry out repair work.
Reduce the load!
Actuate aeration valve.
– Top up the oil.
– Actuating the aerating valve.
Close the oil filler screw.
Clean or replace. If working under the load
is unavoidable, first close the oil filler
screw fully and check function, the load
must remain at the same height for 5
minutes. Hydraulic oil may only be topped
up by trained personnel.
Replace sealing elements. Remove leaked
oil immediately. Adhere to the safety
provisions on the data sheet of the
hydraulic oil used.
Actuating the aerating valve.
NOTICE: The jack may not be operated with
defects. Defects must be rectified
immediately by an expert.