| 摘要 |
<p>A hoist system includes a winch drum and an air motor coupled to the winch drum. The hoist system further includes a brake coupled to the winch drum and operable to stop rotation of the winch drum and an over-speed sensing device configured to sense a speed of the winch drum. The over-speed sensing device includes a pneumatic switch operable to disconnect an air supply from the air motor and engage the brake to stop rotation of the winch drum and a centrifugal clutch coupled to the winch drum and configured to rotate at a rotational speed proportional to the speed of the winch drum. The centrifugal clutch operates the pneumatic switch when the rotational speed of the centrifugal clutch reaches or exceeds a threshold rotational speed.</p> |
