| 摘要 |
A lifting device for massive precast concrete wall units having spaced parallel front and rear wall panels and spaced apart lateral connecting arms therebetween. The device comprises a pair of pivotally connected lifting legs swingable between retracted and expanded positions. The legs have a spreader element pivotally connected therebetween intermediate their ends. At upper ends a pair of connecting links are respectively connected pivotally at lower ends with the legs and pivotally connected together at upper ends. A lift attachment is also pivotally connected at upper ends of the connecting links. At lower ends the legs have fixed or pivotal shoes with outwardly projecting toes which engage beneath the bottom surfaces of the arms of the wall units with the legs expanded. With the legs retracted the legs and shoes are freely moveable vertically between the arms of the wall units. Shoes are selectively mountable on the legs in pairs with horizontal and at least one other toe angle. A manually operable locking mechanism secures the legs in retracted position in an overcenter position and, when released, the legs assume their expanded position at the urging of gravity.
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