Patent ID: 7396057
Filing Date: 2008-07-08
Classification: B66C

Abstract:
1. A lifting magnet comprising a housing; a rotary magnet unit rotatably accommodated in the housing and comprising a pair of permanent magnets having opposite magnetic poles and a rotational shaft; a stationary magnet unit comprising a pair of permanent magnets surrounding the rotary magnet unit and facing each other across the rotary magnet unit and determining a magnetization state and a demagnetization state according to rotated positions of the rotary magnet unit, the lifting magnet further comprising: a pinion coupled to the rotational shaft; a socket moving up and down within a predetermined lifting stroke with respect to the housing; a slider comprising a toothed rack portion to be engaged with the pinion, moving up and down within the lifting stroke, and rotating the pinion to set the magnetization state at a top dead point and set the demagnetization state at a bottom dead point; a locking part provided in one of the socket and the slider; a locking unit provided in the other of the socket and the slider, comprising a locker to be locked to and released from the locking part, and moving both the socket and the slider up and down in the state that the locker is locked to the locking part; and a locking unit driver alternately driving the locking unit to release the locker from the locking part at a first moving operation of the socket, and to lock the locker to the locking part at a second moving operation of the socket.