Dimensions and Load Ratings for Single-Row 02-Series Deep-Groove and Angular-Con

Question

Dimensions and Load Ratings for Single-Row 02-Series Deep-Groove and Angular-Contact Ball Bearings The bevel pinion drives the bevel gear. The free body diagram of gear shaft is shown. The thrust load is supported by a deep-groove ball bearing at C. The gear shaft diameter is 25 mm. The shaft rotates at 300 rpm with no impact. The desired life is 4000 hours and the bearing set reliability is 95%. Select an appropriate deep-groove bearing at C from Table 11-2. Comment on the selected bearing for its desired application.

Explanation / Answer

Part a:

Assumptions:

1) Considering steady loads i.e. S=1

2) Considering Inner race rotation factor i.e. V=1

Given:

Fx = 1.5 KN

Fy = 1 KN

Fz = 5.3 KN

N = 300 rpm

Solution:

Step-1 : Find the equivalent load as follows

We know,

P = S[X.V.Fr + Y.Fa]

Here,

S, X, Y and V = 1 as per our assumption

and, Fr = [ (Fy)2 + (Fz)2 ]1/2

putting values, Fr = [ (1)2 + (5.3)2 ]1/2 = 5.39 KN

and we already know that Fa = Fx = 1.5 KN

So, P = [5.39 + 1.5] = 6.89 KN

Step-2: Calculate life at 90% reliability

We know that in order to find out the dynamic load capacity we have to use the following formula:

L90 = [C/P]k

where,

L90 is life of bearing at 90 percent reliability

C is dynamic load capacity

P is equivalent load

and K = 3

Now to find L90 following formula is to be used:

L95/L90 = [ ln(1/R95)/ln(1/R90) ]1/1.17

here R95 = 0.95 and R90 = 0.90

therefore

L95/L90 = 0.54

So, L90 = L95 / 0.54

But L95 = 4000 * 60 * 300 = 72 * 106 revolutions = 72 MR

So, L90 = 72/.54 = 133.33 MR

Now put all these values in above equation:

L90 = [C/P]k

C = P(L90)1/k = 6.89(133.33)1/3

C = 35.19 KN

So by using thisvalue of dynamic load capacity we can see in the table that appropriate bearing can be selected as given in the eleventh row from the top.

Part b:

The selected bearing is deep groove ball bearing. This bearing can be used for high radial and low axial loads.

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