STRAIGHT-LINE CIRCULAR ARC CURVE (DWELL-RISE-DWELL CAM)

To improve the poor condition of sharp bumps on straight-line cams, we can smooth out the junction between the dwells and the rise. This is often achieved by employing circular arcs tangent to both straight-line rise and dwell curves .Usually, the circular arc is formed by a radius equal to the rise h. The shorter the radius, the nearer is the approach to the undesirable condition of the straight-line curve. A longer radius produces a more gradual action at the beginning and at the end of the curve. Although such a curve is an improvement over the straight line curves, it can be applied for low speeds only, since large accelerations exist at the beginning an at the end of the stroke.