Self-loading flat-bed truck

Claim 1

IN COMBINATION WITH A WHEELED VEHICLE HAVING A LOADRECEIVING FLAT BED EXTENDING BETWEEN OUTWARDLY FACING LONGITUDINAL CHANNEL MEMBERS OF A VEHICLE FRAME, A RESPECTIVE RAIL EXTENDING LONGITUDINALLY OF THE BED IN SURMOUNTING RELATION TO SAID CHANNEL MEMBER, A RESPECTIVE CARRIAGE PROVIDING WHEELS AT THE FRONT AND REAR ENDS RIDING UPON EACH OF SAID RAILS, ROLLERS JOURNALED FROM EACH OF THE CARRIAGES BEARING UPON THE UNDERSIDE OF THE UPPER FLANGE OF THE RELATED CHANNEL TO COUNTER FORCES IMPOSED UPON THE CARRIAGES TENDING TO UP-END THE SAME, A RESPECTIVE SET OF FRONT AND REAR SPROCKET WHEELS JOURNALED AT EACH SIDE OF THE BED FOR ROTATION ABOUT TRANSVERSE HORIZONTAL AXES WHICH COINCIDE AS BETWEEN THE TWO SETS, A RESPECTIVE CHAIN FOR EACH OF SAID SETS TRAINED ABOUT THE SPROCKET WHEELS AND DEAD-ENDED TO THE RELATED CARRIAGE, SAID CHAINS AND THE SPROCKET WHEELS ABOUT WHICH THEY ARE TRAINED BEING WHOLLY HOUSED BY THE RELATED CHANNEL MEMBER OF THE FRAME IN THE SPACE BETWEEN THE CHANNEL FLANGES, POWER-DRIVEN MEANS FOR TURNING SAID TWO SETS OF SPROCKET WHEELS IN UNISON IN EITHER DIRECTION SELECTIVELY FOR MOVING THE CARRIAGES ALONG THE RAILS, A UNITARY SWING-FRAME FORMED TO A YOKE SHAPE SO AS TO PROVIDE UPRIGHT SIDE ARMS CONNECTED ACROSS THE TOP BY A BRIDGING CROSS-ARM AND HAVING THE LOWER ENDS OF SAID SIDE ARMS CO-AXIALLY PIVOTED ONE TO ONE AND THE OTHER TO THE OTHER OF THE TWO CARRIAGES FOR FORE-ANDAFT SWING MOVEMENT ABOUT A TRANSVERSE HORIZONTAL AXIS, HOIST MEANS CARRIED BY THE CROSS-ARM OF THE SWING-FRAME, AND POWER-OPERATED MEANS FOR MOVING SAID SWING-FRAME IN ITS SAID SWING MOVEMENT.