The Dolly Master™ is a fast and economical way to spot converter dollies in the yard. The Dolly Master is an air-operated, all steel, truck-mounted system featuring a vertical slide with 1.75˝ coupling pin. A double-acting air cylinder, using the trucks air supply, moves the slide up and down. The pneumatic control switch is located inside the cab for driver convenience. The Dolly Master is not intended for use in trailer coupling or trailer spotting.