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| Illustration 1 | g01621472 |
Some of the hydraulic lines have been removed for photographic purposes. The hydraulic and steering vane pump is mounted to the front side of the transfer gear case. | |
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| Illustration 2 | g01621473 |
(1) The small section of the hydraulic and steering vane pump supplies oil to the control valve. (2) The large section of the hydraulic and steering vane pump supplies oil to the steering control valve. | |
The hydraulic and steering vane pump is a two-section vane pump. The pump draws oil from the hydraulic oil tank.
Note: The large section and the small section of the pump operate similarly. An explanation of the operation of a typical vane pump follows.
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| Illustration 3 | g01621474 |
Schematic of the Carriage Assembly for a Typical Vane Pump (3) Rotor (4) Cam ring (5) Outlet (6) Passage (7) Inlet (8) Inlet (9) Outlet (10) Vane (A through G) Locations of the vanes (AA) Pressure oil (BB) Supply oil | |
The carriage assembly for a typical vane pump is composed of the following components:
- A plate
- An adapter
- Seal packs
- Rotor (3)
- Cam ring (4)
- Vanes (10)
Vanes (10) are pushed outward by centrifugal force. The pressure oil in passages (6) keeps the vanes (10) along the contour of cam ring (4) . Both ends of the vanes are connected by these passages. The oil in these passages keeps the pressure equal on both ends of the vanes. Also, the oil behind the vanes is allowed to escape as the vanes are pushed inward.
As rotor (3) turns clockwise, the vanes in positions (G) and (F) move outward along the contour of cam ring (4) . As the chamber area between the vanes increases, the oil pressure drops and a vacuum is created in the chamber. This pressure difference causes oil to flow from the hydraulic oil tank and through inlet (8) . The oil fills the space between positions (F) and (A) .
Oil between the vanes at positions (F) and (E) will be trapped when the vanes pass the end of inlet (8) . As rotor (3) continues to turn, the vanes are pushed inward by the contour of cam ring (4) . The chamber area between the vanes now decreases. The pressure of the oil increases.
Pressurized oil between the vanes at positions (A) and (B) is pushed into outlet (5) . The oil continues to be pushed through the outlet between positions (B) and (C) . When the vane at position (B) passes the end of outlet (5) , the cycle is complete.
Note: The oil that enters through inlet (7) flows through the cartridge assembly and through outlet (9) similarly.