Foldable wheelchairs

A foldable wheelchair comprising two side frame assemblies connected together by a foldable link to which a flexible seat panel is secured extending between said two side frame assemblies, said two side frame assemblies each having a rear upright frame member to which a flexible back panel is secured also extending between said two side frame assemblies, each said side frame assembly mounting a front castor wheel, a rear castor wheel and a further rear wheel positioned outboard and adjacent to said rear castor wheel, each said rear castor wheel being slidably supported on the respective rear upright frame member for vertical movement relative to said adjacent further rear wheel between a raised position and a lowered position, respective spring means biassing each said rear castor wheel to said raised position, a respective manually operable control mechanism for each said rear castor wheel, each said control meachanism including a handle located relative to the respective rear upright frame member for accessbile actuation by the user seated on the wheelchair, each said handle being mounted for swinging movement from a first postion to a second position and being operatively connected to a respective control rod to move the respective rear castor wheel to the lowered position against said spring means on actuation of said handle and, a respective releasable mounting for each said further rear wheel whereby, in said raised position, each said rear castor wheel is clear of the ground and each said adjacent further rear wheel engages the ground for manual self-propulsion of the wheelchair by the user seated on the wheelchair and, in said lowered position, each said rear castor wheel engages the ground and each said adjacent further rear wheel is raised clear of the ground to permit removal of said further rear wheel from the respective mounting with subsequent advancement of the wheelchair being achieved on said front and said rear castor wheels.