The caster wheel is subjected to the two couples. Determine the forces F that the bearings exert on the shaft so that the resultant couple moment on the caster is zero.
Image from: Hibbeler, R. C., S. C. Fan, Kai Beng. Yap, and Peter Schiavone. Statics: Mechanics for Engineers. Singapore: Pearson, 2013.
Solution:
Let us write a moment equation assuming clockwise rotation is positive.
\circlearrowright^+ \sum M_A=0;
0=(-500)(50)+(F)(40)
0=(-500)(50)+(F)(40)
(Remember that our resultant couple moment on the caster should be zero, so our net moment is 0. Also, note that we did not convert mm to m as this was not necessary.)
F=625 N
Where you not suppose to convert mm to m?
It is not necessary.