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# Note for Kinematics of Machinery - KM By Dhanen Thiran

• Kinematics of Machinery - KM
• Note
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Dhanenthiran M
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SRMTRPEC DEPARTMENT OF MECHANICAL ENGINEERING which are connected by pin joints, multiplied by the radius of the pin  Rubbing velocity of pin = ( ωA + ωB ) * r (links moves in Opposite direction)  Rubbing velocity of pin = ( ωA - ωB ) * r (links moves in Same direction) 8 Define Velocity ratio theorem.  The magnitude of the velocities of the points on a link is directly proportional to their distance from the instantaneous centre. The direction of their velocities is perpendicular to the line joining them with the instantaneous centre 9 Explain the radial component of acceleration  Radial component of acceleration is perpendicular to the velocity of the particle at the given instant.  The magnitude is given by arBA= ω2 . AB = v2BA/AB 10 What is the objective of Kinematic analysis?  The objective of Kinematic analysis is to determine the Kinematic quantities such as displacement, velocity and acceleration of the element in a mechanism TWO MARKS ME8492-KINEMATICS OF MACHINARY

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SRMTRPEC DEPARTMENT OF MECHANICAL ENGINEERING Unit 3- KINEMATICS OF CAM MECHANISMS 1 State the expression for maximum acceleration of a follower moving with cycloidal motion.  Maximum acceleration of a follower moving with cycloidal motion is a = 2πω2s / θ2 where a=acceleration, ω=angular velocity of cam, s= stroke of follower, θ=angle moved 2 Why sometimes the axes of translating roller followers in cam follower mechanisms are offset from the axis of rotation of cam?  When the motion of the follower is required away from the cam axis then it is offset from the axis of cam. Specially used in translating followers where the follower is required to move fast and to very less distances. 3 Define Pressure angle  It is the angle between the direction of the follower motion and a normal to the pitch curve. This angle is very important in designing a cam profile. If the pressure angle is too large, a reciprocating follower will jam in its bearings. 4 What is a tangent cam?  When the flanks of the cam are straight and tangential to the base circle and nose circle, the cam is known as tangent cam. 5 Define undercutting in cam. How it occurs.  The cam profile must be a continuous curve without any loop. If the curvature of the pitch curve is too sharp, then a part of the cam shape would be lost and thereafter the intended cam motion would not be achieved. Such a cam is called an undercut cam.  Undercutting occurs in the cam because of attempting to achieve too great a follower lift with very small cam rotation, with a smaller cam. 6 What are the classifications of follower according to follower shape and different motion of the follower?  According to follower shape Knife edge follower , Roller follower , Mushroom or flat faced follower, Spherical faced or curved shoe follower  Different motion of the follower Uniform velocity, Simple harmonic motion, Uniform acceleration and retardation, Cycloidal motion 7 Why a roller follower preferred to that of a knife-edged follower?  A roller follower is preferred to that of a knife edge follower because the end of the follower is sharp in knife edge follower and roller in roller follower.  The rate of wear is high in knife edge follower to reduce the rate of wear the roller followers are extensively used. TWO MARKS ME8492-KINEMATICS OF MACHINARY