| 摘要 |
<p>A hoist limiting system (15) comprising a frame (16), a hoist drum or sprocket (17) supported by the frame and rotatable about a hoist axis ( x-x ), a hoist driver configured to rotate the hoist drum, a hoist line (18) in engagement with the hoist drum, at least one gear (20) mechanically coupling the hoist driver and hoist drum and configured to rotate about a gear axis ( x-x ), the gear having a face (21) that rotates about the gear axis, a first proximity limit switch (26) adjacent the rotating face such that the rotating face moves relative to the proximity switch and a second proximity limit switch (28) adjacent the rotating face such that the rotating face moves relative to the second proximity switch, the first and second proximity switches configured to sense the presence or absence of the face and communicating with a controller (29), the first and second proximity switches, the control unit, and the hoist driver configured to prevent the hoist drum from rotating in the upward direction and in the downward direction as a function of the signals from the first and the second proximity switches. The gear has four elongated slots (22-25) arranged around the gear axis, the switches being arranged to sense the slots.</p> |
