Various categories of hydraulic pumps exist, each possessing distinct capabilities and constraints. Determining the appropriate pump type for a hydraulic system application can pose a challenge, yet a fundamental grasp of the prevalent hydraulic pump varieties serves as a solid foundation.

Fundamentals of Hydraulic Pumps

The primary objective of a Car Lift Repair Near Me hydraulic pump is to propel hydraulic fluid throughout a hydraulic system, akin to the core of its functionality. Common traits shared by all hydraulic pumps include their provision of hydraulic flow to other system components (such as rams, hydraulic motors, cylinders) and their generation of pressure when encountering resistance to flow. Additionally, most hydraulic pumps are motor-driven and incorporate a pressure relief valve for overpressure safeguarding. Presently, the three predominant types of hydraulic pumps are gear, piston, and vane pumps.

Gear Pumps

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In a gear pump, hydraulic fluid gets confined between the pump’s body and the spaces amidst the teeth of its interlocking gears. One gear is powered by the driveshaft while the other remains stationary until meshing with the driving gear. These pumps are identified as fixed displacement or positive displacement, as each shaft rotation displaces a consistent volume of hydraulic fluid at a consistent pressure. There are two primary variants of gear pumps—external and internal, which we’ll explore shortly.

Gear pumps boast a compact design, rendering them suitable for applications with spatial limitations. Their simplicity facilitates maintenance and repair. It’s noteworthy that gear pumps typically exhibit optimal efficiency at maximum speed. Generally, external gear pumps can achieve higher pressure levels (up to 3,000 psi) and greater throughput than vane pumps.

External Gear Pumps

External gear pumps are often encountered in closely integrated designs, where the pump and hydraulic motor share the same mounting and shaft. In this configuration, fluid flow occurs around a pair of meshed external spur gears. Hydraulic fluid movement between the pump’s housing and the gears facilitates the alternating suction and discharge required for fluid flow.

However, when engineered to handle even higher pressures and speeds, they can become notably noisy, necessitating special precautions.

Internal Gear Pumps

In an internal gear pump, the interaction between external and internal gears, along with a crescent-shaped sector element, facilitates fluid flow generation. The outer gear features inward-pointing teeth, while the inner gear sports outward-pointing teeth. As these gears rotate and engage and disengage, they create suction and discharge zones, with the sector serving as a barrier between these zones. A special type of internal gear pump called a gerotor eliminates the need for a sector element by utilizing trochoidal gears to establish suction and discharge zones.

Unlike external gear pumps, internal gear pumps aren’t suited for high-pressure applications; however, they generate flow with minimal pulsation. While less common in hydraulic systems compared to external gear pumps, they find utility in applications involving lube oils, fuel oils, and metering.

Piston Pumps

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Piston pumps employ reciprocating pistons to alternately generate suction and discharge. These pumps can be categorized based on whether their pistons are axially or radially mounted, as well as whether their displacement is fixed or variable.

Car Lift Repair Near Me Piston pumps can withstand higher pressures than gear or vane pumps of comparable displacement; however, they tend to incur higher initial costs. They are also more vulnerable to contamination, necessitating adherence to strict hydraulic cleanliness standards and thorough filtration of any introduced hydraulic fluid.

Axial Piston Pump

In a Car Lift Repair Near Me axial piston pump, also referred to as an inline axial pump, pistons align with the pump’s axis within a circular cylinder block. Inlet and outlet ports reside on one side of the cylinder block, while an angled swashplate occupies the opposite side. 

Axial piston pumps excel in high-pressure, high-volume applications and are commonly employed in critical hydraulic systems such as those found in jet aircraft.

Bent-Axis Pumps

Bent-axis piston pumps, considered a subtype of axial piston pumps, feature a pump composed of two sides meeting at an angle. On one side, the drive shaft rotates the cylinder block containing pistons, which correspond to bores on the opposite side of the pump. As the cylinder block rotates, the distances between the pistons and the valving surface vary, thereby facilitating suction and discharge.

These pumps are engineered for heavy-duty operational cycles, including hydrostatic transmissions and power machinery.

Radial Piston Pump

Car Lift Repair Near Me Radial piston pumps feature pistons arranged radially, perpendicular to the pump’s axis, resembling spokes on a wheel around an eccentrically placed cam. Upon rotation of the drive shaft, the cam displaces and compresses the spring-loaded pistons inward as it passes them. Each piston possesses its own inlet and outlet ports leading to a chamber, within which valves regulate hydraulic fluid release and intake.

Radial piston pumps find application in machine tools and serve as power sources for hydraulic systems such as cylinders.

Fixed Displacement vs. Variable Displacement

In fixed displacement pumps, each reciprocation discharges a consistent volume of fluid. Conversely, variable displacement pumps permit adjustment of the swashplate angle to increase or decrease fluid volume discharged. This design flexibility enables system speed variation without altering engine speed.

Vane Pumps

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In vane pumps, rigid vanes mounted on an eccentric rotor pick up hydraulic fluid upon rotation of the input shaft, transporting it to the pump’s outlet. The space between vanes increases on the inlet side, drawing hydraulic fluid into the pump, and decreases on the outlet side, expelling hydraulic fluid through the output port. Vane pumps may feature either fixed or variable displacement, similar to piston pumps.

While Car Lift Repair Near Me vane pumps have historically found use in utility vehicles, their prevalence has diminished with the rise of compact, robust gear pumps. However, they still serve in various applications, excelling at generating effective vacuums and sustaining operation even in dry conditions for brief periods.

Pump Selection

Choosing the appropriate hydraulic pump entails considering factors beyond pump type, including the hydraulic fluid type, operating speed, maximum pressure, displacement type, flow rate, torque ratings, and power curves. Nevertheless, determining the required pump type constitutes a pivotal starting point.