The development of compact motors and cleaning tools has increased the use of floor polishers both in industry and in the household. The cleaning part of these appliances consists of two or three brushes or pads for functions including:

> Polishing/buffing hardwood floors and other materials.
> Removing stains from carpets.
> Stripping floors and applying wax.

The brush and pad rotation is achieved by universal motors. These motors can be placed either in the machining or brush cases. Motor power varies between 0.5-1.5 KW giving a rotor speed of approximately 1000 rpm.

HCH bearings for rotor movement
The rotor of the universal motor is supported by two single row deep groove ball bearings. To ensure good protection against ingress of dust and other particles whilst cleaning, the bearings need to be fitted with contact rubber seals. The internal radial clearance is optimized to meet the machine design and to achieve a good compromise between noise and temperature rise. The bearings are charged with the optimum quantity of the appropriate grease to ensure good lubrication for the machine' s service life.

Improved service life can be achieved for HCH bearings due to:

> Extended grease life
> Good performance in air-streams and condensation
> High wear resistance against particulate contamination (sand, pigments, abrasives, steel, iron oxides etc.)
> Resistance to electric current

● The radial clearances of bearings with electric motor quality

Tolerance in μm.

Bore				CM
Over		Including		Min.	Max.
mm	Inch	mm	Inch	μm	μm
10	0.3937	18	0.7087	4	11
18	0.7087	24	0.9449	5	12
24	0.9449	30	1.1811	5	12
30	1.1811	40	1.5748	9	17
40	1.5748	50	1.9685	9	17
50	1.9685	65	2.5591	12	22