A bed frame assembly includes a base frame 32, an elevatable frame 40 and a lift system 80. The lift system includes a carriage 82 longitudinally translatably mounted on the base frame and a lift arm 84 having a crank end 86 and a remote end 88. The crank end of the lift arm is mounted to the carriage at a pivotable joint A for pivoting about a laterally extending crank axis 100. The remote end of the lift arm is connected to the elevatable frame by a lift arm connector 102, which may take various forms. The lift system also includes an actuator 120 mounted on the carriage at a juncture B and connected to the lift arm such that operation of the actuator rotates the lift arm about the crank axis. The lift system also includes a part span connector 130 pivotably connected to the lift arm at a joint D and pivotably connected to the base frame at a joint C. In one embodiment the lift arm connector is a single link 132. In another embodiment the lift arm connector comprises multiple links such as first and second links 144, 146.
