Apparatus for moving vehicles such as caravans and trailers

Apparatus for moving a trailer comprising a pair of drive units (10,11) which are mounted or mountable on a trailer and comprise drive motors (20) having friction rollers (22) movable into and out of driving engagement with the respective wheels, the apparatus having a control system for controlling the operation of the drive units (10,11) which is operable to cause any selected one of the drive units to operate in steps interrupted by periods of braking each followed by a period of no operation of the unit. The driving and braking periods are shorter than period of no operation. The control system is also operable to cause the drive units to operate at different speeds.