Fluidlexikon

Hydraulic power pack

A hydraulic power pack is a stand-alone assembly consisting of a drive motor, hydraulic pump and hydraulic fluid tank. The drive motor is connected to the hydraulic pump via a shaft and drives this. The motor and pump can be installed on the tank, as well as inside the tank in oil. The tank size, withdrawal, feed and critical flow speeds depend on the task and application, and must be configured accordingly. The extracted volume is determined in accordance with the size of the consumers and thus the overall need for fluid in the hydraulic system. The warming of the fluid, as well as potential leakages must be taken into consideration here. The critical flow speed occurs at the smallest diameter. The pump is driven by the electric drive and converts the electrical energy into hydraulic energy. This is also referred to as hydraulic pressure being created and a flow rate being provided. Using connections enables this to be used for drive in machines.

Further components can also be installed directly on the power pack:

Depending on the design, a distinction is made between standard hydraulic power packs, oil immersed hydraulic power packs and compact hydraulic power packs (also mini power packs). In the case of oil immersed hydraulic power packs, the electric drive is integrated directly in the tank (Submerged motor). This enables particularly small exterior dimensions to be achieved for the power pack. As the electric drive is in the hydraulic oil, the lost heat from the motor is transferred to the oil. If the switch-on duration is too long, this could result in an impermissibly high oil temperature. In the case of a compact hydraulic power pack, the electric drive is mostly flange-mounted on the outside of the tank.

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Standard hydraulic power pack (source: HAWE Hydraulik SE)

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Oil immersed hydraulic power pack (source: HAWE Hydraulik SE)

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Compact hydraulic power pack (source: HAWE Hydraulik SE)

To optimise energy efficiency, it is worth considering the relative switch-on duration (duty type) and therefore the number and duration of switching cycles per time unit in a specific application case. This loading is described as Nominal mode of operation in the international standard IEC 60034-1. It will be familiar from selecting appropriate motors and can also be applied when choosing hydraulic power packs.