US Patent 8662217 Additional roller in a fixed frame

A hospital bed with a chassis and with four rollers arranged on the chassis has at least one further auxiliary roller that can be brought into contact with the floor or that can alternatively be driven. The auxiliary roller is mounted on a rigid frame and, together with the frame, can be raised or lowered relative to the chassis by pivoting. A drive motor is secured on the frame and drives the auxiliary roller. A separate pivot drive is provided for raising and lowering the auxiliary roller. The separate pivot drive is secured entirely on the frame and pivots with the frame.