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 thrusters 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 thruster reaches its maximum value here. The drive motor is therefore relieved in the resting position of the piston. Mechanical overloading of the thrusters is not possible.
The electrohydraulic system used by the ELDRO® thrusters, 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