Actuator with approach pre-stroke and working stroke for operating a tool

摘要

In the present invention, there is disclosed an actuator effecting an approach pre-stroke and a working stroke for maneuvering a tool, comprising an actuator body (21) in which at least two pistons (26, 31) are mounted so as to be able to slide in the actuator body, either in the same direction or in opposite directions, when extracted from the actuator body, namely a pre-stroke piston (26) and at least one working piston (31) actuating the tool. Said actuator further comprising locking means disposed between said actuator body (21) and the pre-stroke rod joined to said pre-stroke piston (26), these locking means operating at least in the retraction direction thereof, characterized in that they comprise at least one lock (43') designed to slide transversely in a front cylinder head of said actuator body (21), this lock (43') being provided in the form of a small piston and being biased, by an external pressure, so as to lock in a pocket (45') of said pre-stroke rod, by compressing a return spring in the unlocking position. Said locking means operate between the pre-stroke piston (26) and the actuator body (21) and the pre-stroke rod (29) is coupled with said pre-stroke piston (26). Both, a working rod (34) and said pre-stroke rod (29) are displaced in the same direction between their retracted position inside said actuator body (21) and their extracted position, wherein the working rod (34) is slidably mounted in an axial bush inside said pre-stroke rod (29).