Overload Protection; Port Positions; Start-Up - Danfoss Vickers VMQ125S Service Manual

Section IV —
Installation and Operating
Instructions (cont.)
E. Hy draulic Fluid Recommendations (cont.)
F. Overload Protection
G. P ort Positions
H. Start-Up
1 Single, Double, T riple and Thru-drive Pumps Overhaul Service Manual V-PUVN-TS001-E October 2002
The pump cover can be
assembled in four positions
with respect to the body.
A letter in the model code
identi es the orientation of the
inlet and outlet ports. The cover
position of a VMQ single pump
is shown in Figure 8 as an
example.
Whenever it is possible to do
so, ll the pump ports with
system hydraulic uid. This
will make it easier for the
pump to prime when it is rst
started.
Sound Lev el
Noise is indirectly af fected by
the uid selection, but the
condition of the uid is of
paramount importance in
obtaining optimum reduction
of system sound levels.
Some of the major factors
a ecting uid conditions that
cause the loudest noises in a
hydraulic system are:
1. Very high viscosities at start-
up temperatures can cause
pump noises due to cavitation.
2. R unning with a moderately
high viscosity uid will slow
the release of entrained air. The
uid will not be completely
Relief valves must be installed
in the system as close to the
pump outlets as possible. The
relief valve limits pressure in
each system to a prescribed
maximum and protects
Disassembly and assembly procedures are in Section
Cover (Inlet)
C
D
A
Model
V M Q * 1 * * A * 0 0 3
V M Q * 1 * * B * 0 0 3
VMQ1* *C* * 030
VMQ1* *D* * 030
Figure 8.
Self pr iming: W ith a minimum
drive speed of 600 RPM, a
pump should prime
immediately. Failure to prime
within a short length of time
may result in damage due to
lack of lubrication. Inlet lines
must be tight and free from air
leaks. However, it may be
purged of such air in the time it
remains in the reservoir and air
will be recycled through the
system.
3. Aerated uid can also be
caused by ingestion of air
through the pipe joints of inlet
lines, high velocity discharge
lines, cylinder rod packings, or
by uid discharging above the
uid level in the reservoir. Air in
the uid causes a noise similar
to cavitation.
4. Cont aminated uids can
cause excessive wear of
internal pump parts, which
may result in increased
sound levels.
components from excessive
pressure. Each relief valve
pressure setting depends on
the work requirements of the
circuit being fed.
VI-B and E.
Body (Outlet)
B
I
nlet Cover Positions
(Viewed from cover end)
O p p s o e t i O l t u t e P o t r
0 9 °Clockwise from Outlet
Inline with Outlet
90° Counterclockwise from Outlet
Cover Positions
necessary to loosen a tting on
the outlet side of the pump to
purge entrapped air.
No load star ting: These
pumps are designed to start up
with no load on the pressure
ports. They should never be
started against a load or a
closed center valve.