Chain lifting device having a safe descent stroke

摘要

The present invention provides a chain lifter with safe descending stroke, which comprises: a lifting body, a motor, a driving sprocket group, a linkage mechanism, a first safe switch and a second safe switch. The linkage mechanism is composed of a first rocking rod, a second rocking rod, a first connecting rod, a second connecting rod and an elastic resetting mechanism which are in the same plane. The first end of the first rocking rod is connected with a first adjusting wheel, the first end of a second rocking rod is connected with a second adjusting wheel. In the present invention, the lifting body is provided with a linkage mechanism which can reset automatically by collaborating with the rocking rod, the linkage crank and the adjusting wheel to change the wrap angle of the chain on the wheel and automatically adjust the looseness of the loose edge of the chain, so as to ensure the lifter to be provided with enough descending stroke when the lifter touches the ground, to prevent from operation fault and accidents caused by the over-loosening or over-tightening of the chain, and to increase the operation reliability and safety of the lifter observably.