An undercarriage, particularly for stretchers, which has multi-height adjustment and does not need to be manually raised or lowered by the attendant when being loaded into, or unloaded from, an ambulance. The undercarriage includes a rectangular support structure, a wheeled height adjustable framework...http://www.google.ca/patents/US5509159?utm_source=gb-gplus-sharePatent US5509159 - Undercarriage
