Brush pressure calibration apparatus and method

A method of correlating a frictional force of a pair of scrubber brushes with a gap distance between the brushes, comprising the steps of:

• providing at least one test plate;
• placing said at least one test plate between the brushes;
• rotating the brushes against said at least one test plate;
• measuring the frictional force exerted by the brushes against said at least one test plate;
• and
• correlating the frictional force with the gap distance between the brushes.

A method of correlating frictional forces between a pair of scrubber brushes with a gap distance between the brushes and determining a degree of parallelism between the brushes, comprising the steps of:

• providing a pair of test plates;
• placing said pair of test plates between the brushes;
• rotating the brushes against said pair of test plates;
• measuring the frictional forces exerted by the brushes against said pair of test plates, respectively;
• and
• correlating the frictional forces with the gap distance and the degree of parallelism between the brushes.