| 摘要 |
PCT No. PCT/GB95/02208 Sec. 371 Date Aug. 16, 1996 Sec. 102(e) Date Aug. 16, 1996 PCT Filed Sep. 18, 1995 PCT Pub. No. WO96/08657 PCT Pub. Date Mar. 21, 1996A pneumatic device 10 comprises a piston 12 moveable along a cylinder 10. The piston has opposite ends 18, 26 defining a space 30 therebetween. The space is divided into two chambers 30a, 30b by a housing 40 fixed relative to the cylinder and having a fluid flow control passageway 42 therethrough. The space 30 is filled with fluid, such as oil. The piston 12 is arranged such that movement thereof against a spring 16 causes the fluid to be displaced from one chamber 30a of the space 30 to the other chamber 30b through the passageway 42. The spring 16 is arranged to apply a return force to the piston 12 and the rate of return of the piston 12 is controlled by the return flow of fluid through the passageway 42. A pneumatic system 100 includes a device 10 connected between first and second members 58, 58a of a building, such as a door and door frame. The pneumatic system comprises a source of compressed gas C for operating the device 10 to enable the device 10 to move the first member 58 relative to the second member 58a, ie to open and close the door. A switching device 72 controls the supply of compressed gas to the device 10. |
