formed on and projecting from the end of the reinforcing plate for engagement with a hole formed in an end wall of the slot the hook engaging the hole by a slight clockwise rotation of the reinforcing plate as it is inserted into the slot in the direction of the arrow of fig6 the more important advantages of the invention may be summarized as follows since the diameter of the through hole bored in the reinforcing plate is larger than that of the mounting hole in the guide body when the reinforcing plate is situated in the slot of the guide body and guide is supported on a shaft extending through the holes of both parts the shaft is not contacted by the inner periphery of the reinforcing plate consequently objectionable metallic noise is avoided and the noise due to the pivoting motion of the guide is remarkably reduced furthermore wear in the through hole portion of the reinforcing plate is avoided so that it is not necessary to subject the reinforcing plate to a strengthening process such as heat treatment or the like consequently the production cost of the guide can be reduced additionally distortion due to heat treatment and the like is also avoided and efficient insertion of the reinforcing plate into the slot of the movable guide in the assembly process is also improved since the shaft supports the inner walls of the two parts of the mounting hole transverse vibration due to pivoting of.