Electrohydraulic thruster ELDRO® DC unit

The latest high quality industrial brakes

All ELDRO® electrohydraulic thrusters are characterized by the highest operational safety and longevity through a wear-resistant operating principle. The hydraulic system provides soft, shock-free operation and short positioning times. An intelligent device design allows easier handling during installation and removal.


The basic components of the ELDRO® Thruster, i.e. electric motor and closed hydraulic system are coaxially assembled to form a functional unit. The working fluid of the hydraulic system serves as the operating medium for the generation of thrust.

Method of Operation

In the switched-off state (de-energised), the hydraulic piston with the piston rod is at its lower limit. In the switched-on state, the centrifugal pump delivers the working fluid under the piston and produces there hydraulic pressure, i.e. the thrust of the ELDRO® unit. As a result of this pressure, the piston travels along its path against the internally fitted braking or re-setting spring or against an external load. The work resulting from the product of 'force x distance' is transmitted via the piston rod and the pressure lug to the device to be operated. Thus, the piston can either travel the total stroke distance or the externally reduced stroke lengths.

In accordance with the hydraulic transmission principle, at each end position of the piston, motor power consumption decreases relative to power intake for lifting action. Simultaneously the pressure within the thruster reaches its maximum value. The driving motor is therefore less loaded when the piston is at rest. In that way the ELDRO® Thruster becomes insensitive to mechanical overloads e.g. blocking of the brake. The result of all these factors is that electrical thermal protection is unnecessary. The thrusters are equipped with asynchronous motors.

Mains voltage fluctuations therefore have minimum influence only on the function of the thrusters as the motor speed is primarily frequency dependent, and less voltage dependent. When the thruster is in the isconnected state the piston returns to its original position under the impact of the external force (braking spring or weight). Except for the starting and running down phases of the motor, the lifting and lowering speeds are linear. The response times obtained depend on the magnitude of the load as well as on the viscosity of the working fluid injected, which in turn is effected by the ambient temperature.