| 摘要 |
<p>1. A lifting device, especially a pulley block composed of a shell (102; 202) provided, in its upper part, with a hanging element (107; 207) and made of two parallel wings (103, 104; 203, 204) one of which (104; 204) has a notch (115) ; an axis (108; 208) ; a sheave (109; 209) movable on said axis (108; 208) and situated between the two wings (103, 104; 203, 204) of the shell (102; 202) ; and at least two fixed sheaves (1141 , 1142 ; 2141 , 2142 ) placed on an end of the axis (108; 208) projecting with respect to the wing (104; 204) of the shell (102; 202) in which the notch (115) is realized, fixed sheaves on which one of the tackle-falls (123) of the rope (113) wound about the movable sheave (109; 209) is apt to be wound after passage through the notch (115) made in the wing (104) of the shell (102) interposed between the movable sheave (109; 209) and the fixed sheaves (1141 , 1142 ; 2141 , 2142 ), characterized in that it comprises a shoe (131; 231) co-operating with the movable sheave (109; 209) in order to be able to immobilize the latter, the shoe (131; 231) being mounted on a sliding plate (132; 232) brought back toward the centre of the movable sheave (109; 209) by the tackle-fall (123) of the rope (113) passed, in downward step, on the lower part (135; 235) of the shoe (131; 231) before to be passed on the fixed sheaves (1141 , 1142 ; 2141 , 2142 ).</p> |
