US Patent 7503439 Retractable wheel assembly

A retractable wheel assembly (110) for a carrier (100) is disclosed wherein the wheels (120) are rotatably mounted in cowls (130), which are pivotably disposed in wheel wells (116L, 116R) on a housing. The cowls are connected with a cowl axle assembly (140) that includes a coil spring, preferably a constant force spring (150) that biases the cowls towards a retracted position. The constant force spring is connected to a retractable handle (104), preferably with a spring engagement member (160), such that extending the retractable handle will bias the cowls towards an extended position, wherein the wheels extend out of the wheel wells for use.