Theory of Machine
The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω₁ rad/s in the clockwise direction and the link OB turns with angular velocity ω₂ rad/s in the anticlockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)

(ω₁ + ω₂) r
(ω₁ - ω₂) r
ω₁.ω₂.r
(ω₁ - ω₂) 2r

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Theory of Machine
In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon

Radius of circular arc, cam speed, location of centre of circular arc and roller diameter
Mass of cam follower linkage, spring stiffness and cam speed
Total lift, centre of gravity of the cam and cam speed
Total lift, total angle of lift, minimum radius of cam and cam speed

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