Track assembly for a storage system

A system for guiding the movement of one or more load handling devices in operation, the system comprising:

• a) a first set of parallel tracks and a second set of parallel tracks, the first and second sets of parallel tracks sharing a common track, each track of the first and second sets of parallel tracks providing a track surface;
• and
• b) a first load handling device and a second load handling device, each of the first and second load handling devices comprises a vehicle body, and including a wheel assembly said wheel assembly having a first set of wheels at the front and back of the vehicle body and a second set of wheels at the sides of the vehicle body such that at least one wheel either side of the vehicle body, the first and second sets of wheels being movable vertically for respectively engaging with the track surface of the first and second sets of parallel tracks such that the wheel assembly of the first and of the second load handling devices is configured for engaging with the track surface of the common track;
• wherein each track of the first and of the second sets of parallel tracks include only two guide surfaces extending from the track surface for guiding the first and second load handing devices along their respective first and second sets of parallel tracks,
• the only two guide surfaces of each of the first and second set of parallel tracks being configured to guide the first load handling device along a first path of the common track and the second load handling device along a second path of the common track, said only two guide surfaces are provided by a single lip either side of the track surface, such that the track surface extends continuously between the single lip either side of the track;
• the first set of parallel tracks includes a first track disposed laterally on one side of the common track and the second set of parallel tracks includes a second track disposed laterally on the other side of the common track such that the first load handling device is constrained to move along the first path of the common track and the second load handling device is constrained to move along the second path of the common track.