| 摘要 |
PURPOSE:To facilitate mounting and demounting and to enable prevention of fall-off due to vibration and a wind pressure, by a method wherein a marker plate is mounted to a mounting device which is forced into contact with the retainer part and the engaging part of a coupler and has a side plate with a thumbscrew with a control plate and a top plate being forced into contact with the upper surface of a projection. CONSTITUTION:Mounting of a mounting device 15, to which a reflection marker plate 3 is secured, to a coupler 2 is such that, when, with a thumbscrew 23 unscrewed, the mounting device 15 is lowered from the upper part of a nuckle 5, the mounting device 15 is lowered in a condition in which a side plate 17 is brought into slide contact with the outer surface of the nuckle 5, and a top plate 20 is forced into contact with the upper surface of a projection 13. This causes engagement of the mounting device 15 with the nuckle 5, prevents the mounting device 15 from falling off in a horizontal direction from the nuckle 5, and also prevents the occurrence of downward fall-off with the aid of the top plate 20. In which case, a projection 22 is engaged with a recess 14, and prevents relative rotational motion between the mounting device 15 and the nuckle 5. When the top plate 20 is forced into contact with the projection 13, with the control plate 24 sprung up, the thumbscrew 23 is screwed in, and in this case, it is thrust into a recess 12. This prevents vertical movement of the mounting device 15, and with the control plate 24 lowered, the thumbscrew 23 is prevented from unscrewing. |
