Danfoss Vickers VMQ125S, Service Manual

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Single, Double, T riple and Thru-drive Pumps Overhaul Service Manual V-PUVN-TS001-E October 2002 1 3
Section V —
Inspection and
Maintenance
A. Inspection
B. Adding Fluid to the System
Table 4 lists the common
difficulties experienced with
vane pumps and hydraulic
systems. It also indicates the
probable causes and remedies
for each of the troubles listed.
It should al ways be
remembered that many
apparent pump failures are
actually due to the failure of
other parts of the system. The
cause of improper operation is
best diagnosed with adequate
testing equipment and a
thorough under-standing of the
complete hydraulic system.
Periodic inspection of the fluid
condition and tube or piping
connections reduce time
consuming breakdowns
and unnecessary parts
replacement. The following
should be checked regularly.
1. All hydraulic connections
must be kept tight. A loose
connection in a pressure line
will permit the fluid to leak
out. If the fluid level becomes
so low as to uncover the inlet
pipe opening in the reservoir,
extensive damage to the
pump can result. In suction or
return lines, loose connections
permit air to be drawn into the
system, resulting in noisy
and/or erratic operation.
2. Clean fluid is the best
insurance for long service life.
Therefore, the reservoir should
be checked periodically for dirt
or other contaminates. If the
fluid becomes contaminated,
the system should be
thoroughly drained and the
reservoir cleaned before new
fluid is added.
3. Filter elements also should
be checked and replaced
periodically. A clogged filter
element results in a higher
pressure drop. This can force
particles through the filter
which would ordinarily be
trapped, or can cause the
bypass to open, resulting in
a partial or complete loss of
filtration.
4. Air bubbles in the reser voir
can ruin the pump and other
components. If bubbles are
seen, locate the source of the
air and seal the leak. (See
Table 3)
5. A pump whic h is running
excessively hot or noisy is a
potential failure. Should a
pump become noisy or over-
heated, the machine should be
shut down immediately and
the cause of improper
operation corrected.
When hydraulic fluid is added
to replenish the system, it
should al ways be poured
through a fine wire screen
(200 mesh or finer) or
preferably pumped through
a 10 micron (absolute) filter.
It is important that the fluid be
clean and free of any
substance which could cause
improper operation or wear of
the pump or other hydraulic
units. Therefore, the use of
cloth to strain the fluid should
be avoided to prevent lint from
getting into the system.
C. Adjustments
No periodic adjustments are
required, other than to
maintain proper shaft
alignment with the driving
medium.
D . Lubrication
Internal lubrication is pro vided
by the fluid in the system.
Lubrication of the shaft
coupling should be as specified
by their manufacturers.
E. Replacement P arts
Reliable operation throughout
the specified operating range
is assured only if genuine
Vickers parts are used.
Sophisticated design
processes and materials are
used in the manufacture of our
parts. Substitutions may result
in early failure.
F. Product Life
G. Troubleshooting
The longevity of these
products is dependent upon
environment, duty cycle,
operating parameters and
system cleanliness. Since
these parameters vary from
application to application, the
ultimate user must determine
and establish the periodic
maintenance required to
maximize life and detect
potential component failure.