ME359 HW04 Machine Elements I

Page 1 of 1

The bearing shown in the figure below is being used in a simple idler pulley application. The

load from the belt, transmitted through the pulley, acts on the bearing as shown.

The bearing currently in the system is SKF Part Number RLS 8 (www.skf.com).

Recommended resource: Machinery’s Handbook

1. Static Load 1. What is the maximum allowable static load on the bearing? Assume normal loading, quiet

operation.

2. What is the Equivalent Static Load on the bearing?

3. Does the bearing meet the requirements for static load?

2. Bearing life 1. What is the Equivalent Dynamic Load, P, on the bearing? Calculate to one decimal.

2. What percentage of the Dynamic Load Rating is the Equivalent Dynamic Load on the bearing?

3. What is the maximum allowable rotation speed of the bearing, in rad/s, if the required life is

3,000hrs (intermittent house hold use)? Round to the nearest full rad/s.

4. What is life of the bearing, in rad/s, if the average speed of the bearing is 500rad/s during its

life? Round to the nearest full hour.

5. What type of life does calculated life time correspond to, e.g. intermittent house hold use?

3. Shaft sizing 1. Use the tables provided on the SKF site through the RLS 8 product data page. Use the “Radial

Bearings with Cylindrical Bore” under the Recommended Fits. A drawing is not necessary. State

the internal diameter of the bearing (in mm) and the tolerance class. Also state the numerical

value of the tolerance class in mm (it should be in the form of +.XXX/-.YYY).

39°

428N Bearing

RLS 8