| 摘要 |
Apparatus for unloading a top unloading mine car that is mounted to pivot about a horizontal axis extending along one side of the base of the mine car includes a hoist chain detachably connected to the mine car at the side opposite the pivotal axis. The hoist chain extends upwardly over a pulley mounted on a positioning crank arm. The pulley moves on rotation of the crank arm from a position substantially vertically above the connection means when the mine car is in an upright position to a position above the pivotal axis. The hoist chain continues around a pulley mounted on a drive crank arm and then to an attachment of restricted mobility. The drive crank arm and the positioning crank arm are rotated in a single direction by drive means which are adapted to rotate the drive crank arm at twice the angular velocity of the positioning crank arm. On rotation of the crank arms the hoist chain rotates the top unloading car past the axis of rotation to dump the contents of the car and returns the car to the upright position. In a preferred embodiment, the attachment of restricted mobility of the hoist chain is a differential pulley. A compensating chain runs from the differential pulley over an idler pulley to a connection on the positioning arm to adjust the effective length of the hoist chain.
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