| 摘要 |
A door-closer comprises a piston 14 connected by a rod 16 with a cam mechanism 17 to 22 for converting reciprocation of the piston to rotary motion of a door-pivoting shaft 11. At one end, the rod 16 has a valve element 33 which is normally urged onto a seat 34 in the piston by the retain spring 13. If an unusually high pressure is established at one side 26 of the piston, for example by unusually rapid closing movement of an associated door, the pressure can prevent the piston moving with the valve element 33 and the rod so that the passage 32 through the piston is opened to relieve the pressure. Alternatively (Fig. 3, not shown) the piston is connected directly to carrier 17, and piston rod 16 extends to a spring abutting nut at the opposite closer end, the nut being adjustable from outside the closer to adjust spring tension and thus the pressure at which valve 34 lifts. The spring abutment on the closer housing may also be adjustable. <IMAGE> |
