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| Illustration 1 | g00294545 |
Top View of the Machine (1) Transmission pump. (2) Steering pump. (3) Implement and pilot/brake pump. | |
Implement and pilot/brake pump (3) is located under the cab on the right side of the machine. The pump is mounted in line with steering pump (2) and transmission pump (1). The pumps are driven by a gear in the torque converter housing.
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| Illustration 2 | g00294539 |
Section View of the Implement and Pilot/Brake Pump (4) Outlet for the pilot/brake pump. (5) Pilot/brake pump. (6) Implement pump. (7) Outlet for the implement pump. (8) Inlet for the implement and pilot/brake pump. | |
The implement and pilot/brake pump is a two-section vane pump. The pumps rotate on a common shaft. The pumps draw oil from the hydraulic oil tank through inlet (8) .
Pilot/brake pump (5) supplies the oil for the pilot valve (oil manifold). Pilot pressure oil exits the pilot/brake pump through outlet (4) .
Implement pump (6) supplies the oil that is needed to operate the bucket and any attachments in the implement hydraulic system. High pressure oil exits the implement pump through outlet (7).
Note: The implement pump and the pilot/brake pump operate similarly. An explanation of the operation of a typical vane pump follows.
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| Illustration 3 | g00299780 |
Schematic of the Carriage Assembly for a Typical Vane Pump (9) Rotor. (10) Cam ring. (11) Outlet. (12) Passage. (13) Inlet. (14) Inlet. (15) Outlet. (16) Vane. (AA) Pressure oil. (BB) Supply oil. | |
The components of the carriage assembly for a typical vane pump include a plate, an adapter, seal packs, rotor (9), cam ring (10) and vanes (16) .
Vanes (16) are pushed outward by centrifugal force. The vanes are pushed outward along the contour of cam ring (10) by pressure oil in passages (12). 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 (9) turns clockwise, the vanes in positions (G) and (F) move outward along the contour of the cam ring. 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 (14). 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 (14). As rotor (9) continues to turn, the vanes are pushed inward by the contour of cam ring (10). The chamber area between the vanes now decreases. The pressure of the oil increases.
The pressurized oil that is between the vanes at positions (A) and (B) is pushed into outlet (11). 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 (11), the cycle is complete.
Note: The oil that enters through inlet (13) flows through the cartridge assembly and through outlet (15) similarly.
Reference: For more information on the specifications for the implement and pilot/brake pump, refer to the Service Manual module Specifications, "Vane Pump (Implement, Pilot and Braking)" for the machine that is being serviced.
Reference: For more information about vane pumps, refer to Special Instruction, SMHS7047.