A table assembly for a patient transfer device has upper and lower tables surrounded by belts which counter-rotate as the table assembly moves between a patient and a supporting surface such as a bed. The table assembly includes integrated means for laterally retracting side plates of the upper table while adjusting incident angles of the side plates and vertically separating the upper table from the lower table. Guide slots in end plates fixed to a slide assembly retain positioning posts attached to ends of the side plates. The slots are inclined upwardly toward a centerline of the table assembly at different angles. A crank moves the side plates using a rotating disk attached to a central frame of the upper table and linkage arms with one end pivotally attached to a peripheral region of the disk and another end pivotally attached to one of the positioning posts.