A bed structure includes a frame 28, a deck framework 50 moveably connected to the frame, a panel 72 moveably connected to the deck framework, and a motion converter 100. The motion converter translates the panel relative to the deck framework in response to either or both of a) relative translation between the deck framework and the frame, and b) relative rotation of the deck framework and the frame. In one detailed embodiment the motion converter includes a rack 102 secured to the frame, a primary gear 124 meshing with the rack, a panel drive sprocket 170 rotatably mounted on the deck framework coaxially with the primary gear, an idler sprocket 192 rotatably mounted on the deck framework remote from the panel drive sprocket, a slider connected to the panel, and a chain 220 engaged with the panel drive sprocket and the idler and connected to the slider.
