Race support, deep ball bearing? 2

[Mandrill22]

Do the inner ring and outer ring BOTH need to be supported on a deep groove ball bearing to support axial load?

The outer ring will be axially supported with a shoulder and the outer ring is press fit. Does the inner ring need to rotate against something, causing friction? Is the blue support needed? It's a 15 lb load, 24 mm OD, 8mm shaft, moving very slowly by hand.

 

[BrianE22]

As long as the bearing can handle the axial load then, no, you do not have to support the inner race.

You've probably just left it off the drawing, but how is the inner race held to the shaft? Generally there would be a press fit so the inner race doesn't turn relative to the shaft. You'd probably also want either a shoulder or retaining rings to provide positive axial retention between the inner race and the shaft.

 

[Mandrill22]

The shaft is press fit and there will only be axial force in the direction of the thrust arrows. there is a seat where the red arrows are and the outer race is pressed in,held in the housing. does that clarify it, or would a sketch help?

 

[electricpete]

inner ring need to rotate against something, causing friction?

No. the blue arrow would represent a support like a shaft shoulder or shaft lock nut. When properly designed and assembled, there should be no relative motion between inner ring, shaft and shaft shoulder/lockout. Hence no friction at the inner ring face.

Is the inner ring rotating or outer ring rotating?

For typical inner-ring-rotating, outer-ring-stationary configuration, there should be a proper interference between inner ring and shaft (which helps prevent relative motion). Assuming the thrust load is applied to the shaft, the thrust load would be transferred from shaft to inner ring to rolling elements to outer ring to housing. And with same assumption, the more important inner ring axial support for the thrust load direction shown would be on the right side of the figure (to help prevent thrust load from causing relative axial movement between shaft and inner ring.). For a thrust bearing application, typically there are axial supports on both sides of inner ring (shaft shoulder on one side and locknut on the other)

Did you draw the colored arrows, or they came out of a reference? Either way, clarify which race is rotating and where the thrust load is applied (inner or outer ring)

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(2B)+(2B)' ?

 

[Mandrill22]

@electricpete @BrieanE22
1. The inner ring is rotating, the outer is fixed (pressed into housing).
2. I just grabbed this image online and added the COLORED notes and arrows.
3. This is actually oriented in the vertical direction. The only load is gravitational from the weight of the hanging components. Roughly 15 lbs. There should be no load in the opposite direction "up". Certainly not enough load to overcome the press fit of the shaft-bearing or bearing-housing.
4. The rotational speed is VERY low. It's just a mechanical system being turned by hand. Thus, to save money, I am using an off-the-shelf H7 tolerance shoulder bolt with a flat on it to turn a clutch device. The flat is NOT on the part of the shoulder that contacts the bearing.
5. The shaft has the D shape to turn a clutch device that provides 2-N-m of rotational resistance to keep the hanging component in place (yaw). The clutch can NOT support axial load, hence the bearing.

 

[tbuelna]

Mandrill22,

Be careful about how much interference your press fits have. With an interference fit on both inner and outer races, your deep groove ball bearing's internal clearance will be reduced. Press fits with excessive interference can even produce sufficient static preload in the bearing to cause brinelling damage. Normal internal radial clearance for an 8mm x 24mm deep groove ball bearing is something like 2-13 micrometer. So control your shaft and housing tolerances accordingly.

 

[geesamand]

Be careful about how much interference your press fits have. With an interference fit on both inner and outer races, your deep groove ball bearing's internal clearance will be reduced. Press fits with excessive interference can even produce sufficient static preload in the bearing to cause brinelling damage. Normal internal radial clearance for an 8mm x 24mm deep groove ball bearing is something like 2-13 micrometer. So control your shaft and housing tolerances accordingly.

C3 clearance bearings are very helpful in managing this issue. I'm told the industry manufactures more C3 than normal clearance. Normal clearance bearings are really only suitable for lightly loaded bearings and ground shaft/housing bore tolerances.

To the original question, I always ensure some kind of shoulder is present to support the thrust load both on the inner and outer race. Even if the shrink fit handles the force, the shoulder helps maintain race alignment. Having snap rings or shoulders on the non-loaded side is optional in my opinion.

 

[electricpete]

Circling back on the original question with the benefit of the figure. It appears your only load is downthrust on the shaft. In that case it is sufficient to have an axial support face above the inner ring (transferring load from shaft to bearing) and below the outer ring (transferring load from bearing to outer ring) as is shown in your newer figure.

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(2B)+(2B)' ?