Bearing Torque - Dynaroll

Bearing Torque - Small diameter (<20mm O.D.) deep groove ball bearings have extremely low and uniform bearing torque characteristics. Even when preloaded as part of an assembly, average bearing torque levels of less than 0.5 gm-cm (0.007 oz-in) are common. Typically, torque is dependent on many factors, including ball size, number of balls, retainer type and looseness, radial play, lubricant type and fill percentage, and applied load.

BEARING TORQUE FACTORS

FACTOR	TORQUE EFFECT
Ball size	Smaller gives lower torque
Number of balls	Fewer gives lower torque
Retainer	Crown gives lower torque, loose clinch for ribbon type gives lower torque
Radial play	Higher gives lower torque
Lubricant	Higher viscosity gives higher torque
Lubricant fill	Higher percentage gives higher torque
Applied load	Higher load gives higher torque

The chart below can be used as a simple guide to expected average torque levels for individual bearings with oil lubricant, however, the user must be cautioned that real-life torque values will vary considerably according to the application.

AVERAGE BEARING TORQUE (GM-CM)

DYNAROLL BEARING SIZE (Inches Series)	RETAINER TYPE	BALL SIZE Inch (mm)	# BALLS	THRUST LOAD (gm)	MAX. AVG. TORQUE (gm-cm), OIL LUBE @ INDICATED THRUST
					RADIAL PLAY Inches (mm)
					MC2 .0001-.0003 .002-.008	MC3 .0002-.0004 .005-.010	MC5 .0005-.0008 .013-.020
09,0,1,1-4, 1-5 144, 155, 156, 168	Crown (W)	<1/16	<13	75	.18	.15	.14
2-5	Ribbon (J)	1/16	6	75	.18	.15	.14
2-6, 2, 166	Ribbon (J)	1/16	<8	75	.2	.16	.15
188	Ribbon (J)	2	8	400	.63	.54	.49
3	Ribbon (J)	3/32	7	400	.65	.55	.5
4	Ribbon (J)	3/32	8	400	.7	.6	.55

For more information and discussion on bearing torque and torque analysis, see Assembly Characteristics section.

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Bearing Torque Dynaroll 2003