| 摘要 |
A spring assembly for manoeuvring a garage door or the like comprises a helical spring 8 and a rigid pull rod 11 cooperating with the latter and extending through it, which pull rod 11 is mounted securely on and projects from an attachment 6 and at its free end has a first holder 10 against which one end of the spring 8 is in contact. The spring 8 is enclosed for reasons of protection in a tube 9 which is coupled to a link mechanism 15 which in turn is coupled to the door. In the tube 9 there is a second holder 12 against which the other end of the spring 8 is in contact and which, upon compression of the spring 8, is driven in the direction towards the holder 10 of the pull rod 11 by longitudinal displacement of the casing 9. Both holders 10, 12 and the spring 8 tensioned between them are at all times located inside the tube 9, even upon full compression or full extension of the spring 8, as a result of which the risk of jamming is avoided. For the purpose of counteracting friction, the cross sectional diameter d of the pull rod 11 is considerably smaller than the internal diameter D of the helical spring 8. A plastic sleeve 16 is preferably inserted into the tube 9 in order to counteract friction between the inside of the tube 9 and the outside of the spring 8. <IMAGE> |
