| 摘要 |
518,888. Pneumatic single-stroke apparatus. NATIONAL PNEUMATIC CO. Sept. 6, 1938, No. 26083. Convention date, Sept. 30, 1937. [Class 8 (ii)] [Also in Group XXV] Doors 2, 3 are operated by means of a pneumatic motor comprising cylinders 4, 5 the opening and closing movements of the doors being effected by communicating the cylinder 4 either to air pressure or to exhaust by means of an electromagnetically actuated valve 7. A common piston rod 8 is coupled to a lever 9 which is connected to a member 15 pivoted to an arm 16 coupled to the door shaft. The member 15 constitutes a switch housing having a tubular extension 21 containing a spring 23 which is held at one end by a plug 22 and at the other bears against a washer 24. An insulating bushing 26 bears at one end against a washer 25 next to the washer 24 and at the other end a washer 28 is fitted to hold a contact ring 27 in place. The end of the switch housing remote from the tabular portion is bifurcated and in elongated holes 32 accommodates a pin 31 on the end of the lever 16. The sides of the switch housing contain spring pressed contact plugs 37 which normally rest on the insulating bushing 26. While the door is being closed the arm 16 is held by the spring 23 with the pin 31 at one end of the slots 32, but if an obstruction is met the spring 23 gives and the bushing 26 is moved so that the contact 27 bridges the contacts 37, and the valve 7 is operated to open the cylinder 4 to exhaust. Thus the motor reverses the movemnt of the doors. In a modification, Fig. 8 (not shown), the housing for the spring is connected to the piston of the motor by a pin-and-slot connection and the switching operation is effected by pivoted movement of contacts actuated by a plunger within the housing. |
