| 摘要 |
700,104. Jib cranes. BRITISH HOIST & CRANE CO., Ltd., and EVANS, P. N. Dec. 5, 1951 [Dec. 5, 1950], No. 29752/50. Class 78 (4). A jib crane comprises a post-like support carrying a winch and a motor forming a unit slueable about a vertical fixed post whilst supported by the post only intermediate its ends. The jib arms 25, Fig. 1, are pivoted to plates 17 welded to a horizontal bar 12 welded to a support 13, and to tie bars 28 having holes 30 for adjustably bolting to a head piece 16. Clamps 14, 15 with closure stops 37 are provided at the bottom and top of the support 13 for securing to an upright post 36 which may be secured to scaffolding, the clamp 14 resting on a clamp 35 on the upright post. The plates 17 are connected by a cross bar 18 which has a handle 20 for slueing. The bar 18 carries two vertical plates 19 which are also connected by a shaft 21 having lugs 22 bolted to plates 17. A motor 43 is mounted between the plates 19 and provides an adjustable drive for friction pinions which can engage friction rollers 41 on the shaft of the winch 23 which is mounted on eccentric bearings. A lever 40 is operated to engage the friction rollers with the friction pinions against the action of a spring which urges the rollers to engage stationary brake shoes. |
