US Patent 7517029 Extension and retraction arrangements with control systems

An extension and retraction arrangement with a trolley structure retained for axial extension and retraction relative to a rail arrangement and a control system with an actuating arrangement and a mechanism for selectively controlling a travel of the trolley structure. In a manual control system, the trolley structure can be mechanically engaged and disengaged in extended and retracted configurations by first and second locking projections respectively. An actuating rod can be actuated by a trigger to pivot the locking projections into and out of engagement with the trolley structure. The trigger can additionally enable a selective release of first and second doors from closed positions. A motorized control system can propel the trolley structure and open and close the doors. A lock and key, an access card and access card reader, or a remote control and remote control receiver can selectively enable operation of the control system.