An over/under monorail system for longwall mining operations can have a single overhead rail mounted trolley system with a pair of over/under mounted trolleys. Upper trolleys can be carried by the overhead rail, and can typically carry hydraulic pipes. A lower rail can be carried by the upper trolleys, and lower trolleys can be carried by the lower rail. The lower trolleys can typically carry electric cables. Some trolleys can be adapted to carry both flexible hydraulic hoses and electric cables, and such trolleys can be carried by either the upper or lower rails, depending upon the design of the overall system.