Hydraulic Vane Pumps

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Hydraulic Vane Pumps

In a vane-type pump, a slotted rotor splined to a drive shaft rotates between closely fitted side plates that are inside of an elliptical- or circular-shaped ring. Polished, hardened vanes slide in and out of the rotor slots and follow the ring contour by centrifugal force. Pumping chambers are formed between succeeding vanes, carrying oil …

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Hydraulic Gear Pumps

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Hydraulic Gear Pumps

Gear pumps are external, internal, or lobe types. a. External. Figure 3-6 shows the operating principle of an external gear pump. It consists of a driving gear and a driven gear enclosed in a closely fitted housing. The gears rotate in opposite directions and mesh at a point in the housing between the inlet and …

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Hydraulic Pump Designs

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Hydraulic Pump Designs

In most rotary hydraulic pumps (Figure 3-3), the design is such that the pumping chambers increase in size at the inlet, thereby creating a vacuum. The chambers then decrease in size at the outlet to push fluid into a system. The vacuum at the inlet is used to create a pressure difference so that fluid …

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Hydraulic Pump Slippage

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Slippage is oil leaking from a pressure outlet to a low-pressure area or back to an inlet. A drain passage allows leaking oil to return to an inlet or a reservoir. Some slippage is designed into pumps for lubrication purposes. Slippage will increase with pressure and as a pump begins to wear. Oil flow through …

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Hydraulic Pump Displacement

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Displacement is the amount of liquid transferred from a pump’s inlet to its outlet in one revolution or cycle. In a rotary pump, displacement is expressed in cubic inches per revolution and in a reciprocating pump in cubic inches per cycle. If a pump has more than one pumping chamber, its displacement is equal to …

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Hydraulic Pump Performance

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Pumps are usually rated according to their volumetric output and pressure. Volumetric output (delivery rate or capacity) is the amount of liquid that a pump can deliver at its outlet port per unit of time at a given drive speed, usually expressed in GPM or cubic inches per minute. Because changes in pump drive affect …

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Hydraulic Pump Classifications

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Hydraulic Pump Classifications

All pumps create flow. They operate on the displacement principle. Fluid is taken in and displaced to another point. Pumps that discharge liquid in a continuous flow are nonpositive-displacement type. Pumps that discharge volumes of liquid separated by periods of no discharge are positive-displacement type. Nonpositive-Displacement Pumps. With this pump, the volume of liquid delivered …

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Electro-Hydraulic Stepping Motors

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Electro-Hydraulic Stepping Motors

An electro-hydraulic stepper motor (EHSM) is a device, which uses a small electrical stepper motor to control the huge power available from a hydraulic motor (Figure 4.10). It consists of three components: 1. Electrical stepper motor 2. Hydraulic servo valve 3. Hydraulic motor. These three independent components when integrated in a particular fashion provide a …

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Limited Rotation Hydraulic Motor

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Limited Rotation Hydraulic Motor

A limited rotation hydraulic motor provides a rotary output motion over a finite angle. This device produces a high instantaneous torque in either direction and requires only a small amount of space and simple mountings. Rotary motors consist of a chamber or chambers containing the working fluid and a movable surface against which the fluid …

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