![]() ![]() If the profile is treated as a large base circle and a small tip circle, joined by a common tangent, giving lift L, the relationship can be calculated, given the angle φ between one tangent and the axis of symmetry ( φ being π / 2 − θ / 2), while C is the distance between the centres of the circles (required), and R is the radius of the base (given) and r that of the tip circle (required):Ĭ = L / 1 − sin φ and r = R − L sin φ / 1 − sin φįig. In designing the cam, the lift and the dwell angle θ are given. This is continuous with a tangent to the tip circle. ![]() Thus, in practice, the points at which lift begins and ends mean that a tangent to the base circle appears on the profile. Ideally, a convex curve between the onset and maximum position of lift reduces acceleration, but this requires impractically large shaft diameters relative to lift. Here, the cam profile is commonly symmetric and at rotational speeds generally met with, very high acceleration forces develop. A common type is in the valve actuators in internal combustion engines. ![]()
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