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Construction and principle of operation
The centrifugal pump impeller coupled to the motor shaft sets up a hydraulic pressure under the piston causing its movement upwards against the external load or against the built-in brake springs.
The oil above the piston is pressed again to the impeller inlet hole through the bypass port. When the motor is switched off, the piston will travel back by effect of external load or inside brake springs. The hydraulic force is nearly independent of piston position into cylinder. The outer load doesn't affect the strain of the motor. If the lifting load overcomes the hydraulic force the piston will not move up, but the electric motor will not suffer any damages. That is a considerable advantage in comparison with magnetic brake thrustor. At lower load the lifting movement becomes quicker and the downward movement becomes slower. The time-load curves are related to rated lifting force.
Applications
ELCO are mainly employed to operate drum and disc brakes. Nevertheless, they might be used in whatever application requiring a straight-line movement.
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