Fifth wheel assembly for bed

摘要

A wheeled carriage for supporting a patient includes a patient support with head and foot ends and a wheeled base supported by castered wheels. An auxiliary wheel assembly is secured to the wheeled base and includes a rotatable support shaft with an axis and a drive pin locked in a keyed surface of the support shaft. A wheel stowing spring is located at an end of the rotatable support shaft to continually urge an auxiliary wheel mounted at one end of an auxiliary wheel support bracket to a stowed position. The auxiliary wheel support bracket is rotatably connected to the support shaft at an opposing end and has a stop mounted thereon. An auxiliary wheel support spring continually urges the auxiliary wheel support bracket in a first direction about the axis of the support shaft so that the stop on the auxiliary wheel support bracket engages a stop element integral with the drive pin. This arrangement maintains the support spring in a pretensioned state. A cam apparatus rotates the support shaft in the first direction against the force of the wheel stowing spring to deploy the auxiliary wheel. In the deployed position, the mass of the wheeled carriage applies a force against the auxiliary wheel support spring that separates the stop from the stop element and pivots the auxiliary wheel support bracket about the axis of the support shaft to maintain the castered wheels and the auxiliary wheel in contact with the floor surface.