S30-50C [Americas] [C002]
This section has a description and the repair procedures
for several different types of hydraulic vane pumps.
While the number and type of parts can be different, the
operation of the vane pumps is the same.
DESCRIPTION (See FIGURE 1.)
The vane pump can have one or two pump sections.
The pump or pump sections have a housing, a pressure
plate, a cam ring, a rotor with vanes and a shaft. Some
of the pumps also have a relief valve. The cam ring,
pressure plate, rotor and vanes fit between the hous-
ings. The rotor and vanes rotate within the cam ring.
Pump (See FIGURE 2.)
The pump is driven by an engine or an electric motor.
When the shaft rotates, the rotor turns within the cam
ring. Either the rotor or the surface of the cam ring is
not equally round. As the rotor turns, there is a varia-
tion in volume between the rotor and cam ring. Centri-
fugal force causes the vanes to follow the inside surface
of the cam ring. The pressure from the oil behind the
vanes make the vanes keep a tight fit with the cam ring.
The ports for the inlet and the outlet are on opposite
sides of the cam ring. As the rotor turns past the inlet
port, the volume is increasing between the vanes.
This increase in volume causes a decrease in the pres-
sure or a vacuum at the inlet port. Because of the dif-
ference in the pressures the oil flows into the inlet port.
The oil between the rotating vanes is moved to the out-
let port. The volume between the vanes decreases near
the outlet port and the pressure increases. Oil is dis-
charged into the system at a higher pressure.
FIGURE 1. VANE PUMPS
4. CAM RING
7. PRESSURE PLATE
8. RELIEF VALVE
13. FLEXIBLE PLATE
14. SUPPORT PLATE
15. VANE SUPPORT
FIGURE 2. OPERATION OF THE PUMP
3. CAM RING