Patent ID: 6073441
Filing Date: 2000-06-13
Classification: F15B

Abstract:
Pneumatic piston-cylinder apparatus of single acting type which performs a working stroke in one working direction, and which is returned to its initial position without any external supply of compressed air, and comprising a cylinder part with a cylinder jacket (1), a front end (2) and a rear end (3), and a piston (5) which is reciprocatable in said cylinder, and further comprising means (39), connected only to the rear end (3) for supply of compressed air, and in which the cylinder (1, 2, 3) is formed with means (10, 25, 4) for draining the air from the unloading side (26) of the piston (5) during the working stroke of the piston, and means (9, 26, 29, 30) for building up a reserve amount of compressed air at the unloading side (26) of the piston (5) which reserve amount of compressed air is utilized for returning the piston to its initial position for the working stroke, characterized in that the means (9, 26, 29, 30) for building up a reserve amount of compressed air at the unloading side (26) of the piston (5) at the end of the working stroke comprises a valve rod (27) which is connected to the piston and which has a tubular valve slide (32) reciprocateable thereon, and whereby the valve slide (32) is normally kept in a position spaced from the piston (5) actuated by a spring (33), and in which the valve slide (32), close to the end of the working stroke of the piston, is forced in the direction towards the piston (5), whereby one or more channels (35, 36) are opened between the pressure chamber (23) of the apparatus and one or more draining tanks (9, 29, 30) in which tanks there is created a pressure which is used for returning the piston (5) to its initial position for the working stroke.