Unlike equipment that carried a variety of loads, like boxcars, flatcars, and gondolas, this four-bay hopper was designed specifically for one cargo: bituminous coal. Its capacity matched the volume of coal that a pair of typical 70-ton freight trucks could carry. And its slope sheets - the angled floors at either end of the car - were set at precisely the angle at which coal would flow easily from its bottom doors. (Covered grain hoppers, for example, require much steeper slope sheets.)
