Abstract: A bed includes a base, a frame supported on the base for relative movement about a horizontal pivot axis between raised and lowered positions, and a drive assembly for driving movement of the frame. The drive assembly includes a drive box supported on the base for pivotal movement about a horizontal axis parallel to the pivot axis of the frame, a motor supported in the drive box, a pair of laterally spaced sleeves supported in the drive box for rotation about horizontal axes that are perpendicular to the pivot axis of the frame, a pair of transmission elements connected between an output shaft of the motor and the sleeves for rotating the sleeves in unison with one another when the motor is operated, and a pair of screws supported in the sleeves for relative rotational movement.