A pneumatic wheelchair cushion system has an air cushion with adjoining separate chambers for cushioning a user's coccyx, ischial tuberosities, greater trochanters and thighs. The chambers are pneumatically interconnected with each other such that pressure on one or more of the chambers is transmitted...http://www.google.co.uk/patents/US5487197?utm_source=gb-gplus-sharePatent US5487197 - Pneumatic wheelchair cushion
