Steerable ultra-low patient bed

摘要

A steerable ultra-low patient bed that incorporates a planetary gear arrangement for maintaining verticality of the caster stem at all height positions of the bed. The bed has legs 30 that are pivotally and translatably attached at their upper end to a frame of the bed and caster support members 33 that are longitudinally aligned with the bed pivotally attached to the lower end of each leg 30 at 39. The caster support members 33 each have a single caster assembly 34 attached thereto. A planetary gear arrangement urges the caster support member 33 to rotate in an opposite direction to the leg 30 when the bed is raised and lowered to maintain the caster stem in a vertical orientation. The gear arrangement preferable comprises a gear 32 fixedly attached to the leg 30 at 39, a ring gear 37 concentric with gear 32 and fixedly attached to the caster support 33, and a support gear 31 rotatably attached to caster support member 33. A caster locking means may also be provided for selectively locking the caster assemblies which may be actuated from either end of the bed using a central actuation mechanism.