DGBB belongs to non-separated bearing features with simple structure, low friction co-efficient and high limit speed. DGBB is the most widely used. This kind of bearing mainly take radial load and certain amount of axial load. When increase radial clearance, then can function as ACBB and take more axial load. Misalignment permitted For DGBB, this capability is limited. The permitted angular displacement between inner ring and outer ring (which means will not result in high load due to this angular displacement) determined by: radial clearance, dimension, structure and all kinds of force and moment. We cannot offer specific data because of the complexity among these above factors. But we can give it is between 2~10 Arcminute considering these factors effect. We should note any misalignment will increase bearing noise and shorten bearing life.  Minimum load  To achieve satisfactory running performance, for DGBB, the others ball bearing and all roller bearing, they must run with given minimum load especially under high speed, high acceleration or frequent changing load direction. Under above situation, ball and cage inertia force plus lubrication friction force may cause bad effect to bearing running and possibly result in damaging sliding between ball and raceway.

The formula to calculate minimum force as below:

Which

Frm = minimum radial load, KN

kr = minimum load co-efficient (table 2，Kr will be doubled if bearing use in pair. ）

V= viscosity under working temperature, mm2/S

n= speed, r/min

dm= average diameter=0.5(d+D), mm

、

When cold start or high lubrication viscosity, may need bigger minimum load. Normally bearing supports weight and external load will be bigger than minimum load. If this is not the case, we have to add axial load or radial load additionally to DGBB. For the application of DGBB, we can add axial pre-load by adjusting inner ring, outer ring or add spring component.

Axial load capability

If DGBB is under purely axial load, then this load should not be over 0.5 C0 value. For miniature bearing (ID is less than 12mm) and light series bearing (diameter series 8, 9, 0 and 1) should not take axial load more than 0.25 times C0. If axial load is big, this will shorten bearing life dramatically.

Bearing equivalent static load

Fa/ Fr≤0.8 时 P0 = Fr ( kN)

Fa/ Fr＞0.8 时 P0 = 0,6 Fr + 0,5 Fa ( kN)

Bearing equivalent dynamic load

P = XFr + YFa

which：

Fr---radial load ( kN)

Fa---axial load ( kN)

X---radial co-efficient

Y---axial co-efficient

Table 1 is only for normal (C0) radial clearance DGBB.

Radial clearance

Radial internal clearance value in table 2. These values follows TB/T4604-1993/ISO5753(R2001)-1991, clearance is before installation without load.