Hydraulic pump provides pressure and volume flow

The hydraulic pump is the core component of a hydraulic system. It ensures the circulation of the hydraulic fluid. In doing so, it generates the pressure in the hydraulic system and drives the volume flow. Hydraulic pumps are available in a wide variety. Their design is crucial for the desired pressure.

Manual Hydraulic Pumps

Manual hydraulic pumps are designed as piston pumps. They are found in the following applications:

• Car jacks
• Pallet trucks
• Engine cranes and transmission jacks
• Manual hydraulic cylinders

With their help, the user can increase their force many times over. However, manual hydraulic pumps are only used in these small applications. In larger hydraulic systems, manual hydraulic pumps may be installed as an emergency backup system.

Electrically Driven Hydraulic Pumps

In demanding hydraulic systems, the motor-driven hydraulic pump is without alternative. For reasons of controllability and energy efficiency, electric motors are usually used for the drive. The design of the hydraulic pump determines its applicability. The following pressure-pump combinations are common:

• Vane pump: 70-175 bar
• Gear pump: 200-300 bar
• Piston pumps: up to 700 bar, in some cases even up to 1000 bar

Vane pumps consist of a housing in which two vane rotors rotate. They are driven by an external gearbox and synchronized with each other. Despite their simple design, they can already develop considerable pressures. However, vane pumps are susceptible to cavitation. For large volume flows, gear pumps are therefore frequently used, even at comparatively low pressures.

The gear pump consists of two eponymous gears that propel the hydraulic fluid. The gear pump is widely used in agriculture and construction. It serves as a pressure source for hydraulically operated equipment such as harvesters, rotary harrows, and similar devices.

Piston pumps generate the highest pressures. A distinction is made between radial and axial piston pumps. They are similar in performance. Their difference lies in their size. The radial piston pump is short but has a large diameter. With the axial piston pump, it is exactly the opposite.

Drives for Hydraulic Pumps

With increasing pump capacity and pressure, a correspondingly powerful drive is required. The motors flanged to hydraulic pumps can therefore assume considerable dimensions. This in turn brings with it a number of technical challenges.

With increasing power, disturbance variables such as temperature and cavitation also grow in a hydraulic system. Both must be actively and passively controlled, otherwise the system will destroy itself in a very short time.

Suitable components include, for example, cooling and filtration systems that keep the hydraulic oil cool and clean. With higher hydraulic pump performance, the design of the entire system becomes increasingly demanding. Highly developed hydraulic systems, such as those used in heavy excavators, are therefore extremely complex and can only be controlled with complex sensor technology.