Freight transportation systems

Claim 1

A FREIGHT TRANSPORTATION UNIT COMPRISING, A VEHICLE INCLUDING A LONGITUDINALLY EXTENDING NARROW RIGID FRAME, THE UPPER SIDE EDGES OF SAID FRAME CONSTITUTING RAILS PROVIDING A LATERALLY EXTENDING TRACK ON THE TOP SIDE THEREOF, A FREIGHT CARRIER INCLUDING A LONGITUDINALLY EXTENDING RIGID FRAME PROVIDED WITH A NARROW SUBSTANTIALLY CENTRALLY DISPOSED AND LONGITUDINALLY EXTENDING SADDLE IN THE BOTTOM THEREOF, SAID SADDLE HAVING A WIDTH ONLY SOMEWHAT GREATER THAN THAT OF SAID VEHICLE FRAME BETWEEN THE UPPER SIDE EDGES THEREOF AND ADAPTED TO STRADDLE LATERALLY THE SAME WITH THE BOTTOM OF SAID SADDLE SUPPORTED ON THE TOPS OF SAID UPPER SIDE EDGES SO AS TO MOUNT SAID FREIGHT CARRIER FRAME UPON SAID TRACK ON THE TOP OF SAID VEHICLE FRAME, SAID SADDLE STRADDLING LATERALLY THE TOPS OF SAID UPPER SIDE EDGES ACCOMMODATING GUIDE LONGITUDINAL MOVEMENTS OF SAID FREIGHT CARRIER FRAME UPON THE TOP OF SAID VEHICLE FRAME INCIDENT TO PLACEMENT AND TO REMOVAL OF SAID FREIGHT CARRIER FRAME WITH RESPECT TO SAID VEHICLE FRAME, AND MECHANISM CARRIED BY SAID VEHICLE FRAME AND SELECTIVELY OPERATIVE BETWEEN ACTIVE AND INACTIVE POSITIONS WITH RESPECT TO SAID FREIGHT CARRIER FRAME WHEN IT IS MOUNTED UPON THE TOP OF SAID VEHICLE FRAME, SAID MECHANISM IN ITS ACTIVE POSITION ENGAGING SAID FREIGHT CARRIER FRAME SO AS TO HOLD IT IN PLACE IN ITS MOUNTED POSITION UPON THE TOP OF SAID VEHICLE FRAME AND IN ITS INACTIVE POSITION DISENGAGING SAID FREIGHT CARRIER FRAME SO AS TO RELEASE IT IN ORDER TO ACCOMMODATE THE ROMOVAL THEREOF FROM SAID VEHICLE FRAME.