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GEOMETRY OF PLANAR CAM PROFILES 215

It is apparent that having e > a would lead to more unbalance, since this would be
equivalent to adding material to the cams, a minimum value of e being preferred in this
case. Choosing e = a and using the maximum value of t cw, we minimize the counterweight
size; in other words, we minimize the radius of the counterweight. With these constraints,
the value of f can be readily computed.
For the case of a speed reduction of 8:1, we computed the counterweight and created
a solid model in Pro/Engineer, as displayed in Fig. 7.26, with the parameters t 2 = 5mm,
a = e = 9.5mm, b = 23.5mm, c = 12.5mm, d 2 = 9.85mm, d 3 = 27mm, t cam = 6mm, t cw =
2
6
8mm, c cam = 9.8235mm, A cam = 1.6253 ¥ 10 mm , and f = 8.7866mm.

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