Electrohydraulic Thrusters

EMG Automation GmbH (Germany)

EMG is a specialist when it comes to intelligent and complex automation solutions and as a technological leader, we are the supplier of choice for many customers.

The main areas of application for series products, individual components and complex system solutions from the EMG group include continuous production processes in the metal, paper and plastic sectors, as well as in the foil and tyre industries.

Products and solutions

The ELDRO® and ELHY® electrohydraulic thrusters from EMG ensure a safe and "gentle" braking process in combination with modern drum and disk brakes. In addition, they ensure personal safety and the safety of machines.

Alongside our decades of experience in the production of brake thrusters, EMG's quality is also ensured by:

  • Consistent compliance with our quality assurance system in accordance with DIN EN ISO 9001 and the legal requirements
  • Verification and validation of the prototypes
  • One-Piece-Flow assembly concept
  • Menu-controlled filling of operating media with an automated test routine
  • 100 % testing of all series devices from the ELDRO® and ELHY® range, including
    • High voltage insulation test
    • Functional test
    ——• 12 hour endurance test
    ——• Test data acquisition and evaluation
    ——• Traceability of the test data for each brake thruster
  • Continuous Improvement Processes (CIP)

Electrohydraulic thrusters ELDROclassic®

Highest quality – Maximum safety

All elements of a hydraulic actuation system are combined in the electrohydraulic thrusters from EMG to produce a compact assembly. When switched off, the hydraulic piston with the piston rod is located in its lower end position. When switched on, the hydraulic pump pumps the operating fluid beneath the piston and, in doing so, generates the hydraulic pressure here. This moves the piston up to the maximum stroke path. When doing this, the counterforce – which is generated through an integrated brake or return spring, or an external load (e.g. a brake) – must be safely overcome.

The maximum stroke path of the devices can be externally arbitrarily limited. This can be the case if the brake to be actuated only requires a reduced stroke path for complete opening. In the respective piston end position, the power consumption of the motor reduces in comparison to the power consumed during the lifting process due to the laws of hydraulics. The pressure in the device reaches its maximum value here. The drive motor is therefore relieved in the resting position of the piston. Mechanical overloading of the devices is not possible.



  • Use of robust asynchronous motors
  • Use of high quality materials
  • Use of the proven hydrodynamic principle
  • Broad standard temperature range from –25 °C to +50 °C, expandable to –45 °C to +80 °C with additional equipment, e.g. heating and use of special operating media
  • Mains voltage fluctuations only have a limited influence on the function of the devices, because the motor speed is predominantly dependent on frequency and less on voltage.
  • No thermal protective circuit required
  • Automatic driving back of the piston to the default position when switched off
  • Linear lifting and lowering speeds (exception: motor start-up and run-down range)
  • No sensitive electronic and sensory installation parts needed for the operating principle
  • Long service intervals

ELDROclassic® Standard series

The electrohydraulic system used by the ELDRO devices, in conjunction with the straightforward integration in brake systems and the simple electrical commissioning process, result in the following features for the diverse operating conditions:

  • High operational reliability
  • Long service life thanks to wear-free operation with permanent self-lubrication
  • Soft and impact-free operation as a systemic result of the hydraulic operating principle
  • Short regulating times
  • Approved continuous operation S1
  • High switching frequency of up to 2000 cycles per hour in switching mode S3
  • Reversing operation without any restrictions
  • Easy installation and removal
  • Arbitrary direction of motor rotation, therefore no changeover contactors required
  • Overloading is not possible during Operation
  • Arbitrary external limitation of the stroke path
  • Stepless extension of the lifting and/or lowering times through the installation of valves
  • The fill level of the operating medium is optimised according to the operating conditions and requires no further inspection.

ELDROclassic® Direct current series

ELDROclassic DC devices are used in systems with an existing direct current power supply. The devices must be connected electrically in parallel to the motors. An electrical connection of the ELDRO motors in series is not possible.

The ELDROclassic DC series is also used to open brakes in the event of a voltage breakdown of the three-phase supply. In this case, these devices are installed in the brake as an additional brake thruster. These devices can then be supplied with a direct current voltage, for example, from a battery. This, for example, enables loads in the lifting unit to be lowered and set down safely.


ELDROclassic® Explosion-proof series

Gases, vapours, fumes and dust are generated or escape during the production, processing, transport and storage of combustible substances in many industrial sectors. When combined with oxygen, an explosive atmosphere can develop. If this ignites, it can result in explosions and cause serious personal injury and material damage. The sectors concerned include, for example, the chemical and petrochemical industries, pharmaceuticals, oil and gas production, mining, as well as the food industry, the biofuel industry and the wastewater sector.´

Explosion-protected ELDROclassic devices are ideal for these areas of application. They comply with current regulations and standards and can be used in a variety of ways.

Hazardous area:

  • I M2 (Mining)
  • II 2G for zone 1 and 2 (above ground)
  • II 2D for zone 21 and 22 (above ground)

Certificate of conformity:

  • ATEX - BVS 05 ATEX E 074 X
  • IECEx - IECEx BVS 12.0014X
  • TP TC - RU C-DE.ГБ04.В.00477


Due to its easy integration into braking systems and simple electrical commissioning, the electro-hydraulic system of the ELDROdynamic® thrusters offers a wide range of possible applications. Typical performance features include:

  • Lower power consumption and self-heating through the use of IE3 efficiency class motors and optimised pump geometry
  • Closing times ≤ 200 ms and stroke times ≤ 700 ms are achieved with the ELDROdynamic® (determined at 80 mm stroke)
  • Stroke lengths up to 500 mm can be realised (deviating requirements on request)

ELDRO® Series ED

The electro-hydraulic system of the EMG ELDRO® thrusters, in combination with the easy integration into brake systems and simple electrical commissioning, provide:

  • Long service life due to wear-free operation with constant self-lubrication
  • Soft and shock-free operation, system-related by the hydraulic operating principle
  • Short setting times
  • Approved continuous operation S1 in the standard temperature range -25°C to +50°C
  • High switching frequency of up to 2,000 switching cycles per hour in switching mode S3
  • Reversing operation without restriction
  • Overloading during operation is not possible
  • External limitation of the stroke as required
eldro series ED

ELHY® Electrohydraulic thruster

The ELHY® devices are available in three different series, all of which exhibit the same functional principle, the same internal design and the same external shape.

The motor housing accommodates the stator of the drive motor, which is designed as a three-phase asynchronous squirrel cage motor. The motor runs in the operating fluid.

The electrical connection is established via the terminal box, which tightly seals the motor housing. The cast feet on the motor housing are used to secure the ELHY® device in place. The impeller of the pump is attached to the motor shaft.

The guide cylinder with the axially movable piston is located above the impeller. The interior of the device is filled with hydraulic fluid up to the level of the filler hole.



The electro-hydraulic system of the ELDROdynamic® thrusters in conjunction with their easy integration into brake systems and the simple electrical commissioning result in the following features for a wide range of application conditions:

  • Lower power consumption and self-heating due to the use of efficiency class IE3 motors and optimised pump geometry
  • Closing times ≤ 200 ms and stroke times ≤ 700 ms are achieved with ELDROdynamic® (determined at 80 mm stroke)
  • Maintenance and service friendly due to modular design
  • Stroke lengths up to 500 mm are possible, differing requirements on request
  • High operational reliability (failsafe)
  • Long service life due to wear-free operation
  • Soft and shock-free operation, due to the hydro-dynamic mode of operation
  • Approved continuous operation S1 and switching operation S3 up to 2,000 operations per hour
  • Any motor rotation direction
  • Overloading during operation is not possible
  • Continuous adjustment of lifting and/or lowering times by installing valves


If required, the ELDROdigital® electrohydraulic thruster can be equipped with sensors of different types as well as an IO-Link-compatible evaluation electronics to record and evaluate sensor and operating data for connection to a condition monitoring system.

Possible additional equipment:

  • pressure sensor
  • analogue displacement transducer
  • temperature sensor
  • force sensor
  • end position sensing