How Many Types of Hydraulic Gear Pumps Are There?

External Gear Pumps: Simple and Reliable

External gear pumps are among the most commonly used hydraulic pumps due to their simplicity and reliable performance. They consist of two meshing gears housed within a pump casing.

Structure: An external gear pump typically includes a driving gear connected to a motor and a driven gear that rotates in the opposite direction. The gears are enclosed in a tight casing that directs the flow of hydraulic fluid. As the gears rotate, fluid is trapped between the gear teeth and the casing, creating a positive displacement effect.

Function: The rotation of the gears moves hydraulic fluid from the inlet to the outlet, generating flow and pressure. Because the gears mesh externally, there is minimal internal leakage, providing steady and predictable flow.

Applications: External gear pumps are widely used in mobile machinery, industrial presses, and hydraulic systems in construction equipment. Their straightforward design makes them easy to maintain and suitable for moderate-pressure operations.

Internal Gear Pumps: Smooth and Quiet Operation

Internal gear pumps offer a different mechanism for moving hydraulic fluid, often preferred when quieter operation or smoother flow is required.

Structure: An internal gear pump consists of a larger internal gear with teeth along its inner circumference and a smaller external gear positioned inside the larger gear. A crescent-shaped partition separates the inlet and outlet chambers within the casing.

Function: As the gears rotate, hydraulic fluid is drawn into the pump through the inlet port, trapped between the gear teeth and the crescent partition, and then forced out through the outlet. This design reduces pulsations and noise while maintaining a consistent flow rate.

Applications: Internal gear pumps are commonly used in machinery that requires precise control of hydraulic fluid, such as in machine tools, plastic injection molding machines, and industrial automation systems. They are suitable for higher-viscosity fluids and moderate to high-pressure applications.

Gerotor Pumps: Compact and Efficient

Gerotor pumps, sometimes considered a variation of internal gear pumps, are compact devices designed for high efficiency and smooth operation.

Structure: A gerotor pump consists of an inner rotor with external teeth and an outer rotor with internal teeth, with the number of teeth differing between the two rotors. The inner rotor is slightly off-center, creating chambers that expand and contract as the rotors rotate.

Function: As the rotors turn, fluid is drawn into the expanding chamber at the inlet and expelled through the contracting chamber at the outlet. This design allows for smooth fluid flow and continuous operation at relatively high speeds.

Applications: Gerotor pumps are often used in automotive power steering systems, small hydraulic circuits, and lubrication systems. Their compact size makes them suitable for applications where space is limited, while providing consistent performance under varying load conditions.

Lobe Gear Pumps: High-Flow and Low-Noise Design

Lobe gear pumps are another type of gear pump, often chosen for applications requiring high flow rates and reduced noise levels.

Structure: Lobe gear pumps feature two or more lobed rotors that rotate in opposite directions within a casing. The lobes do not make direct contact with each other; instead, they create a close-clearance seal to move fluid efficiently.

Function: As the lobes rotate, they trap fluid between the lobes and the pump casing, transporting it from the inlet to the outlet. Because there is no direct metal-to-metal contact between the lobes, lobe gear pumps generate less noise and wear compared to traditional external gear pumps.

Applications: These pumps are used in chemical processing, food production, and pharmaceutical industries where smooth, consistent flow and low noise are essential. Lobe gear pumps can handle higher flow rates and operate effectively with viscous or shear-sensitive fluids.