Industrial Grade Conveyor Trolley for I-Beams and Chain Hoists. 4.9 out of 5 stars. 17. $205.00. on-rail transfer trolleys in stock 120 tons-Perfect Transfer 2019/6/1 · An electric monorail conveyor (EMS) is an ground-free, rail-bound conveyor with individually driven trolleys that move independently on a rail system.