Motor Pump Unit Generation Two

The Next Level of Engineering
RAPA Motor Pump Unit Gen II

The Core of Fully Active Suspensions Systems

Under the motto “We make good things even better,” we provide an insight into our development activities for the next generation of the motor pump unit, or MPU for short. We were honored with the Daimler Innovation Award in 2019 for this technology development. The MPU is in use in the Mercedes GLE and the new S-Class and is designed for a 48-Volt electrical system. Developed by RAPA engineers specifically for premium vehicles and luxury SUVs, the electrohydraulic motor-pump system, is a CAN-connected unit for fully active damper systems, which can actively introduce forces into the chassis in addition to controlled damping.

Looking ahead to future high-voltage applications, RAPA already has solutions up its sleeve: in the future, electric cars and “real” hybrids that have a high-voltage electrical system (400-800 volt) can also be equipped with them.

In the new fully active chassis, the motor pump unit makes a significant contribution to achieving a new level of driving experience, with high comfort on the one hand and gripping dynamics on the other. The new active suspensions of the future are fully active suspension systems that stimulate each wheel individually on the basis of dampers and thus adapt to the road surface. Each wheel is controlled selectively according to the driving situation and the body is thus horizontalized.


  • For Premium Vehicles and Luxury SUVs
  • Fully Electric & Hybrid Vehicle 400 to 800-Volt System
  • Available for Internal Combustion Engine (ICE) and Hybrid 48-Volt Electrical System
  • Features

  • Independent Control on all four Wheels
  • Active Roll Stabilization
  • Equalization of Pitch & Lifting Movements
  • Ground Clearance Control | Easy Entre
  • High Efficiency Recuperation
  • NVH optimized

Product DescriptionSystemHighlightsApplication
The Motor Pump Unit (MPU) is an intelligent hydraulic power unit with electric motor – especially for fully active chassis, and combines innovative concepts from electronics and control technology in a compact and robust electro-hydraulic machine. The system consists of a hydraulic 4-quadrant internal gear machine, permanently excited synchronous machine and a directly integrated control unit including software.

The motor pump system, developed by RAPA engineers specifically for premium vehicles and luxury SUVs, supplements the air suspension system with a partially load-bearing hydraulic system. At each wheel, the damper is connected to the engine-pump unit in the vehicle electrical system via hydraulic lines and thus acts as an actuator. This allows the system to actively and individually control the spring and damper forces at each wheel. Damping and level control are adjusted separately for each wheel and effectively compensate not only roll, but also pitch and lift movements. At the same time, it allows the vehicle to be raised or lowered as required to increase or reduce ground clearance, or keeps the vehicle level constant regardless of the load. In addition, the system can even recover electrical energy and actively introduce forces into the chassis. The engine-pump unit is coordinated via a central control unit including software, which also controls the valves and the compressor for the air spring and thus always controls the entire chassis. Ride comfort and driving dynamics thus reach an unprecedented level – the vehicle floats over the asphalt like a flying carpet.

    Motor Pump Unit Generation Two

  • Pump: 4-quadrant internal gear hydraulic machine
  • Motor: Permanent Magnet Synchronous Machine
  • Control Unit: 400 or 800 Volt
  • Hydraulic Power: 1800 Watt
  • Available as a single component as well as an axle kit
  • Space-optimised | Extremely compact
  • High-voltage technology for integration into the high-voltage electrical system of electric and hybrid vehicles
  • Modular system: 400 volts or 800 volts
  • Electrical energy can be fed back into the vehicle’s electrical system via the generator function of the motor pump unit
  • Integrated pressure sensors to detect actual pressure at the two hydraulic interfaces of the MPU
  • Integrated electronic unit for controlling the MPE, setpoint is simply specified via CAN
  • Addition to the air suspension to increase the function of shock absorbers and independent level control and regulation of damping forces on all four wheels and to compensate for roll, pitch and lift movements. The system represents a solution for applications from the field of comfort & driving dynamics as well as comfort systems.
  • Electrification of hydraulic systems, such as roll stabilizers

Product Lines

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