of the two longitudinal directions of the facility for the purposes hereof it will be assumed that each motor 18 when on is energized to drive such portions in fig1 in the direction indicated by arrow 19 seated on belts 16 and 17 are laterally opposite edges of an article in the form of a printed wiring board pwb 20 supported above plate 11 to be transversely spaced therefrom and to straddle the gap between the two belts the lateral edges of the pwb are disposed adjacent to and are guided by portions of assemblies 12 13 which define for the pwb a longitudinal path 21 of travel in the direction of arrow 19 or in the opposite direction depending on how motors 18 are energized on its upper face the pwb 20 has mounted thereon numerous electrical components 24 and at its far edge the board includes a narrow strip 25 extending along the board 39 s margin and having formed therein aligning holes 26 27 above the path of travel of board 20 are a pair of aligners 28 only one shown adapted when activated to insert tooling pins not shown into holes 26 27 in the board 20 and other boards also above such path are a pair of side clamps 30 31 adapted when activated to clamp down on the laterally opposite sides of a board beneath them positioned adjacent to the rear or trailing.