Crane limiting device

A crane limiting device comprises a limiting switch box, a variable-amplitude transmission device, a lifting transmission device, a first chain tensioner, a second chain tensioner, a variable-amplitude chain, a lifting chain and a winch rack. The limit switch box is a hollow box body, and a box inner cavity is formed in the limit switch box; a variable-amplitude limiting shaft and a lifting limiting shaft are arranged in the inner cavity of the box; a variable-amplitude collision block and a lifting collision block are respectively arranged on the variable-amplitude limiting shaft and the lifting limiting shaft; a variable-amplitude microswitch and a lifting microswitch are arranged on the two sides of the variable-amplitude microswitch; a variable-amplitude limiting chain wheel and a lifting limiting chain wheel are arranged outside the inner cavity of the box; the variable-amplitude chain is wound on the variable-amplitude transmission chain wheel, the first tensioning wheel and the variable-amplitude limit