The chassis 2 comprises first and second chassis members 4, 6 with two spaced apart wheels 10 mounted on each, and a mechanical linkage 8 connecting the chassis members which holds them in parallel planes and enables them to pivot within the planes relative to each other. The linkage may be attached to the chassis at two spaced locations on each chassis member, and have an first operational configuration and a second storage configuration in which the lateral spacing between chassis members is reduced. The linkage may have two cross-members 20 extending laterally from the first to the second chassis member, each end of the cross-members being rotarily coupled to the chassis members. Each chassis member may have a vertical post 14 to which the linkage is coupled by a vertically extending linear sliding bearing 22. Also claimed is a vehicle comprising the chassis and a carriage. The vehicle may be a wheelchair.
