| 摘要 |
PURPOSE:To prevent contact of an unloader with the bottom of hold, by providing a U-shaped core wound with exciting and detecting coils on one scratching vane of the unloader while forming a magnetic path for passing magnetic flux through the core and the bottom of hold when the vane has approached the bottom of the hold. CONSTITUTION:A scratching vane 26 is fixed rotatably by means of a sprocket 24 and a chain 27 through a tubular member 25 at the lower end of an elevator frame 20 for mounting a bucket elevator. A U-shaped core 30 is provided on one vane 29 of the scratching vanes 26 then wound with an exciting coil 31 and a detecting coil 32. When the vane 29 faces the bottom of hold, a magnetic circuit 33 is formed between the core 30 and the bottom of hold 12 but when the elevator lowers excessively and the vane 29 approaches excessively to the bottom of the hold, the flux in the magnetic circuit 33 will increase to increase the output voltage at the detection coil side 32 thereby the prevention of contact is facilitated. |
