A linear conveying unit comprises a rail and a saddle movable therealong. The rail includes two pairs of tracks, with the tracks of each pair being convergent. The saddle carries front and rear groups of wheels for engaging the tracks. Each wheel group includes two pairs of wheels, each pair of wheels having convergent axes of rotation. To adjust the saddle in order to eliminate any gaps between the wheels and tracks, only one wheel of each wheel group is made to be radially adjustable. That adjustment is effected by means of an eccentric sleeve surrounding the wheel axle. The saddle is moved by a drive belt, the ends of which are connected to the saddle by quick-release couplings. The saddle includes a recess which is covered by a metallic tape that is magnetically attracted to a pair of magnetic rims. <IMAGE>
