| 摘要 |
<p>Rectangular plates in the forms of gratings are butted together and fixed using grooves in the undersides of the webs to a network of longitudinal and cross reinforcing members, the plates being of rubber or plastic as in parent patent but at the intersections of the webs are bosses with sloping faces leading down to the riddle openings defined by the webs, whose major dimension is a little less than the diagonal from the corners of adjacent holes in the plate. The floor is free from clogging.</p> |
