| 摘要 |
In the instrument (1) the permanents magnets (4), magnetic yokes (5), polar shoes (5 a ) and sensors (6) are all symmetrically positioned around a cable (2) under control, the sensors (6) being movable from a first closed position in which they slide along the free cable (2), a second open position in which they travel on an obstacle (11) associated to the cable (2) and a third position identical with the first one after overcoming the obstacle (11), the magnetic yokes (5) being removable from the respective instrument seats (13 a ) by means of guiding elements (12, 13) allowing the magnetic yokes (5) to be assembled on and removed from the respective seats (13 a )-( Fig. 3 ). |
