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Variable Speed Pumps, Servo Pumps

Variable speed pumps in their simplest version are frequency-controlled.
They consist of three main components:

  • Variable frequency drive (VFD)
  • Asynchronous motor
  • Voith internal gear pump

For hydraulic systems that place high demands on control engineering, servo pumps are the perfect solution. The basic version of these pump systems also consists of three main components:

  • Servo inverter
  • Synchronous servo motor
  • Voith internal gear pump

The future of hydraulics has arrived with variable speed pump systems. With these pumps, hydraulic systems are achieving a functionality never seen before. You save up to 70% more energy over conventional hydraulic systems. Noise emissions are also lower, in many cases by up to 20 db(A).

Servo pumps control the pressure or the volume flow. They precisely convert electrical energy into the hydraulic energy that is currently needed in the system.
The classic use of valves for control can be either completely or partially omitted. This considerably simplifies every hydraulic system.

We make using variable speed pump systems extremely simple. You give us all the cycle data for your machine or system. We then use this information to determine the necessary pressures and volume flows, and design the pump systems based on that. In the end, you get a complete solution – customized, ready to run, and all from a single source.


Voith GmbH & Co. KGaA
Schuckertstr. 15
71277 Rutesheim, Germany

Tel. +49 7152 992-3
Fax +49 7152 992-400

Technical data

Maximum power per drive 250 kW
Maximum volume flow per pump 625 l/min
Maximum operating pressure 345 bar
Pump type Internal gear pumps with radial and axial gap compensation
Control modes
  • Volume-flow control for speed or position
  • Pressure control for force
  • Possible to superimpose volume-flow and pressure control
Maximum accuracy of pressure control ± 1 bar
  • Conventional field buses
  • Analog standard signals

Typical applications

  • Plastics processing machines
  • Die casting machines
  • Presses
  • Machine tools
  • General mechanical engineering
  • Retrofit of existing hydraulic systems and hydraulic power packs

Advantages and benefits

Features Advantages Benefits
  • Reduced pump speed in the part load range and outside the machine cycle.
  • Up to 70% potential energy savings in hydraulic systems.
  • With considerably lower energy costs, you reduce the total cost of ownership (TCO) for your machine
    or system.
  • Noise emissions are reduced by up to 20 dB(A).
  • Reduced cost and effort for noise abatement. Workplace guidelines can often be met without the need for additional measures.
  • Volume-flow or pressure control directly via the pump system –
    not using valves.
  • Hydraulic power loss in the system is lower.
  • Your cooling system is simpler, saving you investment costs.
  • The level of heat introduced into the hydraulic system is lower.
  • Lower cooling power results in lower operating costs.
  • Components have a longer service life.
  • Reduced oil management costs thanks to lower load on the pressure fluid.
  • Controlling the system requires fewer classic valves or none at all.
  • The system is less complex.
  • Your hydraulic system has a characteristically high reliability and availability.
  • The productivity of your machine or system is high.
  • Highly dynamic control using servo pumps.
  • Low mass moment of inertia of the internal gear pump.
  • Actuator cycle times can be shortened by up to 50%.
  • The productivity of your machine or system improves considerably.
  • Control parameters of the servo pump integrated into the servo inverter.
  • Voith servo pumps are delivered ready to go.
  • This reduces the development times and costs associated with your machine or system.
  • Integration into existing control concepts is easy.
  • Our servo pump systems are ideal for retrofit solutions.

Technical information

Total Cost of Ownership (TCO)

  • Conventional hydraulic systems usually have constant volume flows. As a result, these systems have virtually constant energy consumption.
  • Using servo pumps makes it possible to vary the volume flows in hydraulic systems. In the part load range and outside the machine cycle, the servo pumps operate at lower speeds or stop altogether. Servo pumps reduce the energy consumption by up to 70%.
  • Using servo pumps can reduce the total cost of ownership (TCO) for the hydraulic system by up to 35%.
  • Systems with variable speed servo pumps are amortized in a short time – in most cases, within 1 to 2 years.

Energy Efficiency

Comparison of plastics injection molding machines with different hydraulic systems

Cycle of a plastics
injection molding machine:


Standard machine
Optimized machine
Optimized machine with maximum energy efficiency


Pump Fixed displacement pump
Drive motor Constant speed asynchronous motor
Control modes Using classic valves only
Energy consumption 100%




Variable displacement pump
Drive motor Constant speed asynchronous motor
Control modes Partial use of classic valves
Energy consumption 70%




Voith servo pump
Drive motor Variable speed synchronous servo motor
Control modes Partial or total servo pump control
Energy consumption 30%



  • By many criteria, a drive with Voith servo pumps is better than other drive types.
  • Injection molding machines using Voith servo-pump drives feature low total cost of ownership (TCO), reliable processes and high productivity.