EXAMPLE 12-6

Selection of Cam-Roller for a Designed Cam.

Problem: Select a suitable cam follower for a cam with the following loading.

Given: The maximum dynamic load on the cam is 400 lb. The camshaft speed is 18.85 rad/sec (180 rpm or 3 rps). Minimum radius of curvature of the cam is

1.7 in.

Assumptions: Thrust loads are negligible. The machine operates 24 hrs/day, 365 days/year.

Find: The projected bearing L 10 fatigue life in years.

Solution:

1 From Figure 12-29, choose a 1.5-in-dia #CCFH- 1 1/2-SB cam follower, which is 1/2.26 the radius of the cam’s minimum ñ . This is an acceptable ratio. Its dynamic load rating factor is C = 4 840 lb.

2 The static load rating C 0 = 11 280 lb. The static applied load of 400 lb is obviously well below the bearing’s static rating.

3 Calculate the projected life using equation 12.27b, since it is a roller bearing.

4 Calculate the projected life in years

5 This bearing is obviously very lightly loaded and should outlast the machine.

Copyright 2004, Industrial Press, Inc., New York, NY