Control device for power tools

A movement control device for power tools comprising

• (a) a housing providing a pair of axially aligned independent cylinders,
• (b) a first piston in one cylinder and having an elongated piston rod extending from one side thereof and out of one end of said housing,
• (c) a second piston in the second cylinder mounted upon an elongated piston rod intermediate its ends, with said rod disposed in both cylinders and having one end extending out of the other end of said housing,
• (d) a source of driving medium having communication with said one cylinder for moving said first piston in the direction of said second piston and into contact therewith for correspondingly moving said second piston in one direction in said second cylinder,
• (e) resilient means exteriorly of said housing and connected to said one end of said second piston rod for moving the same in an opposite direction through said second cylinder,
• (f) a hydraulic system in connection with said second cylinder and having open communication to both sides of said second piston therein,
• (g) valve means in said hydraulic system restrictively regulating the flow of fluid from said second cylinder through said hydraulic system so as to regulate the speed of movement of said second piston in one direction by corresponding movement of said first piston through said first cylinder, and
• (h) an electrically controlled flow valve connected in parallel to said valve means in said hydraulic system and having an open and a closed position and adapted to permit, in its open position, free flow of hydraulic fluid therethrough in either direction by movement of said second piston as said said second piston is moved by said first piston and said resilient means, said resilient means comprising a coil spring engaging a spring retainer at one end of said second piston rod exteriorly of said housing so as to move the same in one direction through said second cylinder.