Actuators electrohydraulic

Electrohydraulic actuators have similar performance characteristics and cost/maintenance ramifications. The main difference is that they contain their own electric-powered hydraulic pump. The pump may run continuously or be switched on when a change in position is required. Their main application is remote sites without an air supply when a fail-safe spring return is needed. 

Some lifts use electrohydraulic actuators to hft and fold, with valves and gravity used to lower the lift. Crane lifts may swing out from a post at the front or rear of the side door. Interlocking mechanisms are available with some lifts to prevent the lift from being operated while the door is closed. The Society of Automotive Engineers (SAE) has developed guidelines for the testing of wheelchair lift devices for entry and exit from a personal vehicle. The standards are intended to set an acceptable level of reliability and performance for van hfts. 

Electrohydraulic actuators are among the more common varieties of actuators in the process plant market and are also more accurate in terms of position control. These components have very specific (to a particular manufactiuer) design components. Therefore, terminology in the detailed descriptions that follow is specific to the information source, J.M. Voith GmbH in this case. In the case of requesting competitive bids, the end user should consider requesting similar or alternate features. 

Computer numerical control (CNC) means the digital control of machine tool units that consist of series of integrated mechanical actuators, electrical or electrohydraulic servomotors, power amplifiers, position and velocity sensors, and a dedicated computer running under a real-time operating system. 

The flow of main steam entering the high-pressure turbine is controlled by four control valves. The turbine control valves are adjusted automatically by electrohydraulic servo actuators. These actuators control the turbine speed when it is starting up, and for load control after the turbine-generator unit is synchronised. In series with each control valve is a stop valve, whose function is to shut off and isolate the steam flow to the turbine when required. 

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