19 TRAILERS PROVIDED WITH ONE OR TWO OR THREE PAIRS OF WHEELS OR TRACK LAYING WHEEL UNITS WHICH SUITABLY AND USUALLY BUT NOT INVARIABLY ARE DRAWN BY TRACTORS OR TRUCKS-NAMELY, 2-WAY DUMP TRAILERS, SIDE DUMP TRAILERS, BOTTOM DUMP TRAILERS, STAKE PLATFORM TRAILERS, TRAILERS WITH LOAD-ENGAGING BUNKS, TRACTOR WAGONS, AND QUARRY TRAILERS