| 摘要 |
The invention relates to an apparatus for the exact position feedback of a double-acting power piston in a hydraulic power cylinder subjected to extreme environmental conditions, especially high temperatures, comprising a likewise double-acting detecting (measuring) or follower cylinder having a volume equivalent to that of said power cylinder and including a detecting piston the position of which can be sensed by electric means, wherein a pair of working spaces of power and detecting cylinders are in fluid communication with each other via a connecting pipe, while the respective other working spaces are adapted to be connected to a (pressurized) fluid pump or a reservoir through a control valve. This apparatus comprises pressure limiting switches which are each positioned in said connecting pipe as well as in the fluid line extending between said power cylinder and said control valve; and both said power piston and said detecting piston each include a valve-controlled acknowledgement passage by means of which fluid communication can be established between said two working spaces or of said power and detecting cylinders. |
