Patent GB-1352068-A (GB)
Title: Compressed gas operated thrust piston motors
IPC: F01B17/00
Filed: 1971-03-31
Abstract: 1352068 Pneumatic scribe stroke motor HARRY KRUGER GmbH 31 March 1971 [1 April 1970] 8276/71 Headings F1M and F1P A compressed air operated thrust piston motor is controlled to perform an outward and inward stroke after which the piston is pneumatically held in its retracted position by means of an external manually operated normally closed valve 3, a similarly constructed normally closed valve 4 mounted in the outer end cap 1b of the motor cylinder and opened by the piston 2 at the end of the outward position of its stroke and a main valve 6 comprising a double ended airactuated control piston 21 carrying a slide 28 and a sleeve 27 whereby opposite ends of the motor cylinder are connected to a compressed air supply duct 23 and to an exhaust outlet 29 according to the end position of control piston 21 and hence of slide 28; control chambers 20, 26 for control piston 21 being connected by ducts 19, 34 to valves 4, 3 respectively and being connectable through piston bores 24, 25 and the sleeve 27 to an annular pressure slave 22 of the main valve and an adjustable stop 9 mounted on end cap 1a serves to limit the inward position of the stroke of piston 2. Duct 34 includes a manually operated 3-way cock 7 which in the position shown connects control chamber 26 to valve 3. To initiate the motor stroke valve 3 is momentarily opened by pushing a pin 3a which thus vents duct 34 and hence control chamber 26 and results in piston 21 assuming the upper end position shown, in which the pressure supply duct 23 is connected by a port 15 and a duct 14 to the upper end of the motor cylinder; the lower end of the cylinder being connected through a duct 17, a port 16 and slide 28 to the exhaust outlet 29. The piston 2 on reaching the bottom of the cylinder opens valve 4 and thus connects control pressure chamber 20 to the exhaust outlet 29, supply pressure in control chamber 26 then snaps piston 21 and slide 28 to its lower position in which supply pressure is connected through port 16 and duct 17 to the lower end of the motor cylinder whilst the upper end thereof is connected to exhaust. The piston 2 on being stopped by bush 9 opens a further normally closed valve 5 of similar construction to valves 3, 4 and mounted in said bush but since connection between valve 5 and control chamber 26 is blocked by valve 7 said opening of valve 5 has no effect and the piston is held in its retracted position by pressure below it. A further stroke is initiated by opening valve 3 thus relieving pressure in control chamber 26 which results in control piston 21 assuming the position shown. Continuous reciprocation of the motor piston 2 is effected by switching cock 7 to the position shown in Fig.2 whereof valve 5 is in conduit connection with control chamber 26. In a modification cock (307) Fig.3 (not shown) is located so as to block valve (304) at the bottom of the cylinder  whereof the piston is held in the extended position In a further modification the stop combining the lower end of an axially adjustable spindle (444) Fig.4 (not shown) held by a clamp screw (450).