Inlet
Inlet
Inlet
Shaft
Cam ring
Outlet
Outlet
Outlet
Vane
Pump rotation
Rotor
Section II —
Description (cont.)
B. Assembly and Construction
Section III –
Principles of
Operation
A. Pumping Cartridge
VMQ Pumps can be used in
both industrial and mobile
applications. For pump ratings,
methods of installation or other
application information, refer to
the applicable sales installation
drawing or consult an
application engineer.
Basic Pumps.
The pump
illustrated in Figure 1 is
representative of all single
pumps in this series. The pump
consists principally of an inlet
housing, outlet body, drive
shaft, and pumping cartridge.
The principal components of a
cartridge are an elliptical cam
ring, a slotted rotor splined to
the drive shaft, an inlet and
outlet support plate, two wafer
plates on either side of the
cam ring, and twelve vanes
and under vane pins fitted to
the rotor slots. Fluid enters the
cartridge through the inlet port
in the cover and is discharged
through the outlet wafer plate
and support plate to the outlet
port in the body.
C. Application
As mentioned in Section II,
fluid flow is developed in the
pumping cartridge. The action
of the cartridge is illustrated in
Figure 3. The rotor is driven
within the ring by the
driveshaft, which is coupled to
a power source. As the rotor
turns, centrifugal force on the
vanes, aided by under-vane
pressure fed from the outlet
port, causes the vanes to
follow the elliptical inner
surface of the ring.
Radial movement of the vanes
and turning of the rotor causes
the chamber volume between
the vanes to increase as the
vanes pass the inlet sections
of the ring. This results in a
low pressure condition which
allows atmospheric pressure
to force fluid into the
chambers.
An additional inlet fluid path
exists through a drilled hole in
the cam ring. This hole
connects the inlet port directly
to the inlet areas of the cam
ring and provides an additional
flow path for fluid to get into
the cartridge. See Figure 2.
Fluid is trapped between the
vanes and carried past a
sealing land to the outlet
section of the ring. As the
outlet section is approached,
the chamber volume
decreases and fluid is forced
out into the system. System
pressure is fed under the
vanes via the under vane pins,
assuring their sealing contact
against the ring during normal
operation.
The pin-vane design provides a
means of controlling outward
thrust of the vane against the
ring and maintains tip loads
within reasonable limits. In the
pin-vane cartridge, full system
pressure is continuously
applied only to the cross
sectional area of the pin. This
area is small and thrust is
correspondingly light. This
selective application of
pressure assures that the
vanes will always be in contact
with the cam ring. A detailed
drawing of the VMQ rotating
group can be seen in Figure 4.
B. Vane Pressure Feed
8
EATON Vickers
Single, Double, Triple and Thru-drive Pumps Overhaul Service Manual V-PUVN-TS001-E October 2002
Figure 3
Figure 2
