A wheelchair base, said wheelchair base being usable with first and second drive wheels, first end first and second auxiliary wheels and second end first and second auxiliary wheels, said wheelchair base comprising:
- a base frame;
- a first pivot arm assembly, said first pivot arm assembly including a first assembly first pivot arm and a first assembly second pivot arm, said first assembly first and second pivot arms being pivotally coupled to each other for pivotal movement about a first assembly transverse pivot axis, said first assembly first and second pivot arms defining respectively first assembly first and second auxiliary wheel attachments substantially opposed to said first assembly transverse pivot axis for attaching respectively said first and second end first auxiliary wheels thereto, said first pivot arm assembly further including a first assembly link pivotally coupled to said first assembly second pivot arm at a location intermediate said first assembly transverse pivot axis and said first assembly second auxiliary wheel attachment for pivotal movement about a first assembly link axis substantially parallel to said first assembly transverse pivot axis, said first pivot arm assembly further defining a first drive wheel attachment at a location intermediate said first assembly first and second auxiliary wheel attachments for attaching said first drive wheel thereto;
- and
- a second pivot arm assembly, said second pivot arm assembly including a second assembly first pivot arm and a second assembly second pivot arm, said second assembly first and second pivot arms being pivotally coupled to each other for pivotal movement about a second assembly transverse pivot axis, said second assembly first and second pivot arms defining respectively second assembly first and second auxiliary wheel attachments substantially opposed to said second assembly transverse pivot axis for attaching respectively said first and second end second auxiliary wheels thereto, said second pivot arm assembly further including a second assembly link pivotally coupled to said second assembly second pivot arm at a location intermediate said second assembly transverse pivot axis and said second assembly second auxiliary wheel attachment for pivotal movement about a second assembly link axis substantially parallel to said second assembly transverse pivot axis, said second pivot arm assembly further defining a second drive wheel attachment at a location intermediate said second assembly first and second auxiliary wheel attachments for attaching said second drive wheel thereto;
- said first and second pivot arm assemblies being mounted to said base frame substantially laterally opposed to each other with
- said first and second assembly transverse pivot axes substantially parallel to each other;
- said first and second assembly first pivot arms pivotally coupled to said base frame for pivotal movement respectively about a first and a second assembly first arm axis, said first and second assembly first arm axes being substantially parallel to said first assembly transverse pivot axis;
- and
- said first and second assembly links pivotally coupled to said base frame for pivotal movement respectively about a first and a second assembly link-to-frame axis, said first and second assembly link-to-frame axes being substantially parallel to said first assembly transverse pivot axis;
- said first pivot arm assembly being pivotable relative to said base frame independently of said second pivot arm assembly.