This concise guide briefly outlines some of the main types of hydraulic pumps and their various uses across different industries and applications. It includes whether the hydraulic pump is fixed or variable displacement and other helpful infomation such as expected noise levels, ease of maintenance and other features.
Gear Hydraulic pump
This is the most common type of hydraulic pump and one of the easiest to service and cheapest to replace. These fixed displacement hydraulic pumps and are usually used in open centre hydraulic systems. Gear pumps come in two varieties; internal and external and subvarieties include straight cut and helical spur gears which are commonly used where noise reduction is necessary. If increased pressure is required (these are usually around the 250bar mark) then cast iron can increase up to around 320bar.
Gerotor/Internal Hydraulic Pump
These quiet hydraulic pumps are often used in the automotive industry. They have one external gear rotor and one internal gear which is sealed to the off-centre rotor making the volume change constantly. This is not a hydraulic pump for high pressure applications.
Screw Hydraulic Pumps
Another quiet type of hydraulic pump, the screw pump, consists of 2 helical screws one of which drives at one end. They share common housing in which the fluid passes through only one way. It is therefore a fixed displacement output hydraulic pump. A reliable although low-efficiency pump when used with a high viscosity fluid.
Bent Axis Hydraulic Pump
Commonly found in mobile applications such as plant machinery. Bent axis pumps can be fixed or variable displacement hydraulic pumps thanks to the thrust plate which has a variable angle. This makes the pistons that are attached to the rotating cylinder variable as well and therefore can vary the amount of fluid that is moved during each turn.
Axial Piston Pumps
Similar to the bent axis pump but more compact the axial piston hydraulic pump is highly efficient and economical to produce and therefore maintain. There are a wide variety of options when it comes to the ability to have control over the power, pressure and flow making it suitable for a huge variety of machines and applications.
Radial Piston Pumps
Commonly used in high-pressure hydraulic systems radial piston pumps can be either fixed or variable displacement pumps. When it is variable this is often achieved with adjustment screws or a piston which alters the eccentricity of the ring. The distance between the eccentric ring and the centre line of the shaft changes as the central shaft rotates therefore the radial pistons, of which there is an odd number, are taken through a cycle of pressure and suction.
Vane Pumps
Another hydraulic pump uses an eccentric ring but this time instead of pistons sliding vanes are arranged around the central rotating shaft. The vanes then create the seal required. Often used in hydraulic tools which don’t require much pressure (140bar maximum) they are both reliable and quiet.
If you need more information about the different types of hydraulic pumps that we offer and service please contact us at MCH Hydraulics and our team of friendly and experienced hydraulic engineers will be happy to offer their expert advice or book you in for a service.