To reduce the load to a pinion or the like and to surely prevent the drop and descent of a spud by making a deterrent rod bittern into a tooth space of a rack rod by means of the operation of a handle rod at a time when the spud is clamped tight in a state that this spud is made to go up to the optional position.

A deterrent rod 3 consists of a steel pipe or the like with a diameter of the same degree as a size of a tooth space of a rack rod 2 and being longer than the length of wall thickness of this rack rod 2. Both ends are secured to both tip parts of two turning rods 7 and 7 locked with a bast to both ends of a fulcrum shaft 6 free of rotation. This fulcrum shaft 6 is rotatably inserted into a gap between two support plates 5 and 5, and the deterrent rod 3 is turned round to the side of the rack rod 2 and it is capable of bitting into the tooth space of the rack rod 2. An upper side of the support plate 5 is formed into corrugation, supporting each load of a spud 1 and the rack rod 2. A turning rod 7 is rotated by a turning operation by manual operation of a handle rod 9, thereby making the controlling rod 3 slide on the upper side of the support plate 5 and getting it bitten into the tooth space of the rack rod 2, and thus the spud 1 is made supportable so as not be dropped down.