| 摘要 |
427,474. Counterbalanced supporting mechanism. PIEPER, A. F., 404, West Avenue, Rochester, New York, U.S.A. Oct. 11, 1933, No. 28060. Convention date, Nov. 10, 1932. [Class 52 (v)] [See also Groups XX and XXX] In counterbalancing mechanism comprising an arm mounted to swing vertically on a support and resilient means connected between the arm and the support, one of the tensioning members for the resilient means is moved by engagement with a cam on the support during downward movement of the arm to increase the tension in proportion to the moment of the load at different angular positions of the arm. As shown applied to a bracket for supporting X-ray apparatus the counterbalanced support comprises parallel links 10, 11 pivoted to connecting members 12, 13 the member 13 carrying rotatably the X-ray apparatus 14. The member 12 is rotatably connected to the fixed support 29 by parallelogram linkages 15 .. 18 with connecting members 20, 26 and a link 24 connected between extensions 23, 25 of the links 18, 15. The counterbalancing means comprises compression springs 33 in tubes 32 disposed on opposite sides of the links 10, 11. Rods 34 extending through the springs are provided with nuts 35 for adjusting the tension and have their outer ends pivoted at 36 to the member 13. Collars 40 on the tubes 32 have inwardly-extending pivot members 41 journalled in a bearing 42 connected by a chain 44 with a yoke 43 pivoted a 45 to the member 12. As the links 10, 11 are swung downwardly the chain 44 becomes wrapped round a cam 46 on the member 12 so that the spring tubes 32 are swung successively about the links of the chain and the tension of the spring varied to counterbalance the mechanism in all positions. When the links 10, 11 reach the substantially horizontal position shown in Fig. 7 the bearing 42 is arrested by a stop 47 on the member 12, to prevent the spring passing to a dead centre position across the axis of the link 11. The sections 15 .. 18 of the bracket are locked in any position by a clamp screw 49 extending through the link 17 and engaging a lug 50 on the member 12. Downward movement of the links may be limited by a lug 53 on the link 11 engaging a spring 54 on the holder 13. The X-ray apparatus 14 is mounted on a plate 57 fixed to a hollow rotary member 58, Fig. 3, mounted in a housing 13<a> and provided with slip rings 60 for supplying the current. |
