Patent ID: 8657246

Claim:
A base assembly comprising: a load-bearing base comprising one or more downward-facing recesses; one or more wheels rotatably mounted within the load-bearing base and movable between a first wheel position within the one or more downward-facing recesses and a second wheel position extending out of the one or more downward-facing recesses, an actuating member movably coupled to the base; a transmission rod coupled to the actuating member such that actuation of the actuating member causes the transmission rod to translate relative to the load-bearing base; a pin mounted to the transmission rod; a control plate rotatably mounted to the load-bearing base, the control plate comprising a countoured surface substantially defining a pin path wherein the pin can move from a first stable position and enter into a second stable position along the path upon a first actuation of the actuating member, and the pin can exit the second stable position and return to the first stable position along the path upon a second actuation of the actuating member; and wherein motion of the transmission rod causes the pin to move between the first and second plate positions and the wheels to simultaneously move between the first and second wheel positions.