KINEMATIC MECHANISM
 What is a Mechanism?
 In mechanical arena, these so called Mechanisms are used to produce certain desired
motions in order to produce Work. It can be defined as - The assembly of Links in which
motion to one of the links produces (or) transmits motion to other links.
 What is Kinematic Chain?
 In this, the pairs are so connected that the last link is joined to the first to transmit a
definite complete (or) successful motion - this forms a kinematic chain.
KINEMATIC CHAIN (4 LINK)
 One of the classification of the 4 link kinematic chain mechanism is the Slider – Crank
chain mechanism in which we are going to discuss about the QUICK RETURN
MECHANISM consisting of 3 turning and 1 sliding parts. This can be further classified
into  1) Crank and Slotted Lever type
 2) Whitworth Mechanism
WHITWORTH MECHANISM
Description and Working:In general, these mechanical mechanisms are used to perform certain desired work. These
mechanisms have a wide use in the machines used in the Production Industry. As the
name suggests, the Quick Return Mechanism has its importance in its timing of the linear
motion of the tool fixed to it. It consists of the Rotating Wheel that is fixed to the gear
system and then the Motor. The Wheel consists of a small extension as a rod to the wheel
which slides in the hollow connecting rod (Slider Element). The connecting rod is fixed at
one end at A and the other end is connected to the link 2 which makes the tool slide. This
link slides on the horizontal line of axis of the tool application which can be considered as
a passage (or) a limited runway. The link 2 is connected to the tool with a pin. As this
mechanism has a wide use in Slotting machine and Shaper machine – which creates linear
slots on the work pieces, the feed of the tool is given a precise timing to obtain the perfect
motion to remove the metal without any damage to the tool. Here, the speed is controlled
by the gear mechanism. But when returning, the tool is lifted and is brought back to its
initial position in almost double the speed used during feeding. This speed is achieved
because the end point – A of the connecting rod being fixed and the other freely linked to
transmit motion. During the start of feeding, the Slider element of the wheel in the
connecting rod moves from top side to the bottom. But, during the return as the point – A
is fixed, for a small angle of rotation of the wheel there is double the movement of the rod
as there is less scope for the Slider to move in the Connecting rod.
APPLICATION
Above is a Slotter machine in which the tool is shown which can remove about 2 – 4
millimetres of metal at one stroke. During the return stroke the tool is lifted and is returned
back as mentioned above.