Piston pumps are one example of positive displacement pumps, and they are frequently used in various applications where there is a need to move fluids under pressure. The two major types of piston pumps are axial and radial which differ in the way pistons are arranged and generate pressure.
Axial Piston Pumps: In axial piston pumps, the pistons are disposed radially about a cylinder block moving in the direction parallel with respect to the drive shaft. For such kind of a pump to run, either a swash plate or a bent axis design is used so as to change rotary motion from the drive shaft into linear motion for moving the pistons.
- Swashplate Design: In this system, an inclined non-rotating swashplate is applied. As it rotates, cylinders push pistons against the swashplate to displace them back and forth. The angle of inclination of swashplate determines stroke length of the pistons hence changing it will change pump displacement.
- Bent Axis Design: Bent axis version has its pistons dislocated at an angle relative to that of connected drive shafts. When rotating, these angles make each piston reciprocate within its respective cylinder chambers. Often this design results in higher pressures and efficiencies but possibly more complex designs can be obtained.
For their efficiency and the ability to alter the displacement during operation, axial piston pumps are frequently used. They can be used in marine hydraulics, as well as industrial and mobile applications.
In Radial Piston Pumps: Radial piston pumps have pistons that are arranged at right angles to the drive shaft. Usually, this is through use of an eccentrically rotating cam or similar mechanism which as it spins round forces the pistons to move inside and outside of their respective cylinders situated in a radial manner around the shaft.
- Just One Stroke: These pumps usually have pistons that are actuated only once per cam revolution limiting maximum speed but simplifying design.
- Multiple Strokes: Some radial piston pumps are designed so that each piston is actuated several times within one cam revolution, thus making it possible for higher speeds and smoother operation of the pump.
Because they can generate extremely high pressures and last long, radial piston pumps enjoy reputation. Precise control of fluid movement is often required in applications such as hydraulic presses, high pressure washers and precise hydraulic controls.
Both types of piston pumps can be adapted to deal with different fluids. Additionally, these can be scaled from smaller machines up to huge industrial systems. The decision between using an axial or a radial piston pump is typically based on factors such as required pressure, flow rate, efficiency, cost and specific application needs.
