GB940166A - Improvements in or relating to pneumatic motors - Google Patents

Abstract

940,166. Fluid pressure apparatus. ETABLISSEMENTS L. FAIVELEY. April 11, 1961, No. 13036/61. Heading F1P. A pneumatic motor for controlling a sliding door comprises a first cylinder 1 in which operates a hollow floating piston 16 forming a second cylinder having slidingly disposed therein a motor piston 26 which is attached to the door by a piston rod 31, chambers 32 and 43 within the floating piston 16 being in respective communication with chambers 33 and 42 in the first cylinder 1 by means of orifices 24 and 25 controlled by valves 22 and 23; compressed air from a feed pipe 35 is selectively fed under the control of electro-valves 34 and 38 to the chambers 33 and 42 in the first cylinder 1, the valves alternatively being used to connect the. chambers 33 and 42 to pipes 37 and 39 leading to the atmosphere. The supply of compressed air to and exhaust of the air from the chambers 33 and 42 are respectively controlled by adjustable needle valves 5 and 10 and ball valves 4 and 9. When the rod 31 is to be moved from the retracted position thereof, shown in Fig. 1, to its extended position, valves 34 and 38 are operated so as to put the chamber 33 in communication with the compressed air feed pipe 35, and the chamber 42 in communication with the pipe 39 leading to the atmosphere. Compressed air in the chamber 43 of the floating piston 16 is trapped therein by the valve 23 so that both the floating piston 16 and the motor piston 26 move as a unit towards the right hand end of the first cylinder 1 at a speed determined by the setting of the needle valve 5. When the floating piston 16 reaches the end of cylinder 1 the valve 23 is opened allowing the piston 26 to move further to the right relative to the piston 16 at a speed determined by size of the orifices 24 and 25. A similar operation takes place when the piston rod is retracted. In a second embodiment, Figs. 3 and 4. (not shown), each pair of the valves 4 and 5 and 9 and 10, respectively, are replaced by a single valve having a small orifice in the centre thereof, exhaust of air from the cylinder 1 taking place by the lifting of the single valves from their seatings and supply of compressed air to the cylinder 1 taking place through the central orifices, and valves 22 and 23 are dispensed with, the orifices 24 and 25 being of smaller size.