Abstract: A variable height workstation includes a trolley delivery apparatus for controllably moving a rail section from a gap formed in a subsidiary loop rail to a workstation located remotely from the loop. A pivotal cam is controllably rotated by an actuator and moves with the rail section and arrests travel of a trolley on the moveable rail section so that rail section may be removed toward the workstation while carrying the trolley. The pivotal cam is also capable of accelerating a trolley off the rail section either after the rail returns to its normal bridging position or from the rail section without it being lowered. The trolley delivery apparatus is employed in a subsidiary loop system whereby a preworkstation indexer is located upstream of it to advance individual diverted trolleys onto the moveable rail section.