Abstract: A spray gun reciprocating device has a pair of tracks which are parallel to one another, each track comprises the surfaces of a square tube which are engaged by independently rotatable rollers of each of at least three roller assemblies, the rollers of each assembly having track engaging surfaces which converge towards one another, and the rollers are freely rotatable so that if one roller engages a track surface closely to its axis of rotation with the other roller, there is no skidding of the engaging surfaces.

Abstract: A reciprocating mechanism for applying a reciprocating action to a spray gun comprising a chain multiplier wherein a chain has two ends secured to respective chain anchors and extending over sprockets to have a portion extending between those sprockets, and spray gun mounting means secured to said portion, the chain multiplier being actuated by a ram, so arranged that upon tensioning of the chain, the spray gun mounting means is caused to move even when there is only minute movement of the chain, this being effective to greatly reduce the tendency of the chain to shudder.