involving a rigid member, e.g. pressure bar, table, pressing or supporting the belt over substantially its whole span

Full Title

Machines or devices using grinding or polishing belts (for sharpening cutting edges of tools B24B3/00; portable belt-grinding machines B24B23/06); Accessories therefor > for grinding plane surfaces > involving a rigid member, e.g. pressure bar, table, pressing or supporting the belt over substantially its whole span