Truck tarpaulin and drainage mechanism

Claim 1

IN A VEHICLE HAVING A FREIGHT CARRYING PLATFORM, A TRAVELLING BRIDGE SPACED FROM THE PLATFORM GUIDE MEANS FOR SUPPORTING AND GUIDING SAID BRIDGE TO MOVE ACROSS SAID PLATFORM, DRIVE MEANS COOPERATIVELY COUPLED TO SAID BRIDGE FOR MOVING THE BRIDGE, A ROLLER MOUNTED ABOVE THE PLATFORM, A TARPAULIN WOUND UPON SAID ROLLER, THE FREE END OF THE TARPAULIN BEING AFFIXED TO SAID TRAVELLING BRIDGE, WHEREBY MOVEMENT OF SAID BRIDGE AWAY FROM THE ROLLER DRAWS SAID TARPAULIN OVER SAID PLATFORM TO PROVIDE A PROTECTED FREIGHT CARRYING SPACE BETWEEN SAID PLATFORM AND SAID TARPAULIN, AND SLIP CLUTCH COUPLING MEANS CONNECTING SAID ROLLER TO SAID DRIVE MEANS TO ROTATE SAID ROLLER TO WIND UP SAID TARPAULIN WHEN SAID DRIVE MEANS MOVES SAID BRIDGE TOWARDS SAID ROLLER, SAID SLIP-CLUTCH BEING SO CONSTRUCTED AND ARRANGED TO SLIP AND LIMIT CONNECTION BETWEEN THE DRIVE MEANS AND THE ROLLER WHEN SAID TARPAULIN TENDS TO BE DRAWN ONTO SAID ROLLER AT A SPEED FASTER THAN THAT OF TRAVEL OF SAID BRIDGE TOWARDS SAID ROLLER, WHEREBY A LIMITING TENSION IS ESTABLISHED IN SAID TARPAULIN.