Selective delivery arrangement for self propelled pallet vehicles

Self propelled pallet vehicles (12a) are guided along a track network (10) by downwardly projecting guide pins (350, 352) carried by each pallet vehicle (12) which engage slots (354, 358) in the track network and steer the pallet vehicle (12) along the track network (10). The track network has main (20) and branch (22) track sections, and selective delivery of the vehicles to various destinations along the track network (10) is achieved by controlling the position of the guide pins (350, 352) between alternate rotated raised and lowered positions. In the lowered position the guide pins (350, 352) interact with the track network (10) to guide the pallet vehicle (12) into a branch section (20) of the track. In the raised position, the guide pins (350, 352) cause continued movement of the vehicle (12) along the main track section (22) and past a junction (38). The guide pin position may be controlled by a photoemitter (364) at the junction (38), or by various other alternatives.