Motion Without Limits - Bishop-Wisecarver Corp.
Motion Without Limits - Bishop-Wisecarver Corp.
Motion Without Limits - Bishop-Wisecarver Corp.
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COMPONENTS<br />
TECHNICAL REFERENCE<br />
Load/Life Equation – Sizing and Selection<br />
Step 1: Calculate loads on each bearing<br />
Given below are force equations for some common configurations.<br />
F A = Axial Force, F R = Radial Force<br />
Scenario 1<br />
F A1 = F(x-a)<br />
x<br />
F A2 = Fa<br />
x<br />
a<br />
F<br />
Scenario 2<br />
F A1 = F(x+a)<br />
x<br />
F A2 = -Fa<br />
x<br />
Scenario 3<br />
F A1 = Fx<br />
y<br />
F A2 = -Fx<br />
y<br />
F R1 = F<br />
*Note: Since carriages use 4 wheels, 2 wheels<br />
absorb the load at both points 1 & 2, divide the<br />
calculated load by 2 to obtain the load on each wheel.<br />
Example: Scenario 3<br />
F = 200 lbs<br />
x = 15 inches<br />
y = 5 inches<br />
F A1 = 200(15) = 600 lbs, or 300 lbs per wheel<br />
5<br />
F A2 = -200(15) = -600 lbs, or -300 lbs per wheel<br />
5<br />
F R1 = 200 lbs, or 100 lbs per wheel<br />
F<br />
1 x<br />
2<br />
a<br />
Scenario 1<br />
1 x<br />
2<br />
Scenario 2<br />
1<br />
F<br />
y<br />
Step 2: Calculate the load factor L F for the most heavily loaded<br />
bearing using the above example with size W4X guide wheel, F A(max)<br />
and F R(max) from load rating chart pg 6.<br />
L F<br />
= F A<br />
/ F A(max)<br />
+ F R<br />
/ F R(max)<br />
L F<br />
= 300 / 900 + 100 / 2181 = 0.38<br />
Step 3: Calculate life estimate<br />
See page 23 for life constants, A F assumed at 1<br />
Life = [L C<br />
/ (L F<br />
) 3 ] A F<br />
= [6.84 x 10 6 / (0.38) 3 ] x 1 = 124.7 x 10 6 inches<br />
x<br />
Scenario 3<br />
2<br />
24<br />
© <strong>Bishop</strong>-<strong>Wisecarver</strong> <strong>Corp</strong>oration 2010. All rights reserved www.bwc.com 888.580.8272
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