Hydraulic Mechanical Energy Storage


Hybridization of the traction drive on a hydrostatic counterbalance truck



This project included investigation of the potential fuel savings due to the hybridization of a hydrostatic counterbalance truck with mechanical energy storage and the hybrid vehicle as a functional model. Test drives demonstrated that all of the required system functions can be realized using the drivetrain concept. Fuel savings of up to 10 percent could be determined subject to the dynamics of the driving cycle.

  forklift truck Copyright: © MSE


The frequent acceleration and deceleration phases mean that the potential for fuel savings through recuperation is particularly high in mobile work machines such as counterbalance trucks. Intermediate storage is required to be able to fully recuperate the energy. This combines the advantages of high power and energy density. A flywheel accumulator is suitable for this, which also offers the option of substituting the counterweight and thus actively exploiting the mass that is required in any event.

Research objectives

The objective of this project was to develop hydraulic-mechanical storage in a forklift truck for exemplary purpose, to construct it, and finally to implement and test it in a customary vehicle.

  • Development and construction of a hydraulic-mechanical energy storage system
  • Testing of the flywheel accumulator
  • Integration of the storage system within a test vehicle
  • Development of an operating strategy and implementation on the test vehicle's control unit
  • Determination of the potential fuel savings

Research and project partners


Promoted by

MWEBWV NRW EU Logo Ziel2.nrw Logo    PTJ Logo Copyright: © PTJ

Project sponsor