The basic dynamic load rating is an expression of the load capacity of a bearing based on a constant load which the bearing can sustain for 1,000,000 revolutions (the basic rating life). For radial bearings this rating applies to pure radial loads. The common measurement is “L₁₀” life, defined as the number of revolutions before metal fatigue first appears on 10% of a large group of like bearings. This is referred to as basic rating life of fatigue life.The relationship between the basic rating life, the basic dynamic load rating and the bearing load is given in following formula:

If the speed is constant, the basic rating life can also be expressed in terms of hours of operation (revolution), and is calculated as shown in the formula below:

The relationship between rotational speed “n” and speed factor as well as the relation between the basic rating life and the life factor is shown as following:

Example 1: What is the rating life in hours of operation (L_10h) for deep groove ball bearing 6208 operating at 650 r/min, with a radial load Fr of 3.2 kN?

● Correlation of bearing basic rating life, life factor and speed factor (Ball bearing)

	n	fn	n	fn		L10h	fh	L10h	fh
	10 12 14	1.49 1.41 1.34	600 700 800	0.382 0.362 0.347		100 120 140	0.585 0.621 0.654	2800 3000 4000	1.78 1.82 2
	16 18 20	1.28 1.23 1.19	900 1000 1200	0.333 0.322 0.303		160 180 200	0.684 0.711 0.737	5000 6000 7000	2.15 2.29 2.41
	30 40 50	1.04 0.941 0.874	1400 1600 1800	0.288 0.275 0.265		220 240 260	0.761 0.783 0.804	8000 9000 10000	2.52 2.62 2.71
	60 70 80	0.822 0.781 0.747	2000 3000 4000	0.255 0.223 0.203		280 300 400	0.824 0.843 0.928	12000 14000 16000	2.88 3.04 3.17
	90 100 120	0.718 0.693 0.652	5000 6000 7000	0.188 0.177 0.168		500 600 700	1 1.06 1.12	18000 20000 22000	3.3 3.42 3.53
	140 160 180	0.62 0.593 0.57	8000 9000 10000	0.161 0.155 0.149		800 900 1000	1.17 1.22 1.26	24000 26000 28000	3.63 3.73 3.83
	200 220 240	0.55 0.533 0.518	12000 14000 16000	0.141 0.134 0.128		1200 1400 1600	1.34 1.41 1.47	30000 40000 50000	3.91 4.31 4.64
	260 280 300	0.504 0.492 0.481	18000 20000 30000	0.123 0.119 0.104		1800 2000 2200	1.53 1.59 1.64	60000 70000 80000	4.93 5.19 5.43
	400 500	0.437 0.405	40000 50000	0.0941 0.0874		2400 2600	1.69 1.73	90000 100000	5.65 5.85

● Correlation of bearing basic rating life, life factor and speed factor (Roller bearing)

	n	fn	n	fn		L10h	fh	L10h	fh
	10 12 14	1.44 1.36 1.3	600 700 800	0.42 0.401 0.385		100 120 140	0.617 0.652 0.683	2800 3000 4000	1.68 1.71 1.87
	16 18 20	1.25 1.2 1.17	900 1000 1200	0.372 0.36 0.341		160 180 200	0.71 0.736 0.76	5000 6000 7000	2 2.11 2.21
	30 40 50	1.03 0.947 0.885	1400 1600 1800	0.326 0.313 0.302		220 240 260	0.782 0.802 0.822	8000 9000 10000	2.3 2.38 2.46
	60 70 80	0.838 0.8 0.769	2000 3000 4000	0.293 0.259 0.238		280 300 400	0.84 0.858 0.935	12000 14000 16000	2.59 2.72 2.83
	90 100 120	0.742 0.719 0.681	5000 6000 7000	0.222 0.211 0.201		500 600 700	1 1.06 1.11	18000 20000 22000	2.93 3.02 3.11
	140 160 180	0.65 0.625 0.603	8000 9000 10000	0.193 0.186 0.181		800 900 1000	1.15 1.19 1.23	24000 26000 28000	3.19 3.27 3.35
	200 220 240	0.584 0.568 0.553	12000 14000 16000	0.171 0.163 0.157		1200 1400 1600	1.3 1.36 1.42	30000 40000 50000	3.42 4.72 4.98
	260 280 300	0.54 0.528 0.517	18000 20000 30000	0.151 0.147 0.13		1800 2000 2200	1.47 1.52 1.56	60000 70000 80000	4.42 4.4 4.58
	400 500	0.475 0.444	40000 50000	0.119 0.111		2400 2600	1.6 1.64	90000 100000	4.75 4.9