Theory Of Machine

• Branch : Mechanical Engineering
• Semester : 4^th Sem
• Chapter : 01 Simple Mechanism
• Topic : Fundamentals & types of mechanism
• Faculty : Er. Malabika Nayak

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Theory Of Machine

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Dynamics

Kinetics

Statics

Kinematics

energy it to

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• The Machine receives

in some

do some

available form and uses

particular type of work

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STATICS

• It deals with the study the forces acting on machine in rest.

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DYNAMICS

• It deals with the study the forces acting on various parts of a machine

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KINEMATICS

• It is the study of motion, quite apart from the forces which produce that motion.
• It is the study of position, displacement, rotation, speed, velocity and acceleration.

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KINETICS

• It is the study of inertia force which arries due to combined effect

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• It is defined as the combination of rigid or resistance bodies assembled they having no relative motion in between them and transmit only forces

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 An assembly of moving parts performing a complete functional motion.

A mechanism is a device designed to transform input forces and movement into a desired set of output forces and movement.

Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam and follower mechanisms, and linkages as well as friction devices such as brakes and clutches, and structural components such as the frame, fasteners, bearings, springs, lubricants and seals, as well as a variety of specialized machine elements such as splines, pins and keys.

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• It is defined as a device which receives energy and transforms it into some useful work.
• If the mechanism is used to transmit power (or) to do work, then it is known as machine.
• We can define machine as a device for transferring and transforming motion and force or power from the input that is, the source to the output that is the load

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• It is a resistant body or assembly of resistant body of a machine connecting other parts of the machine with relative motion between them.
• There are three types of links available in order to transmit motion. They are as follows:

» Rigid link

» Flexible link

» Fluid link

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Rigid link

A rigid link is one which does not undergo any deformation while transmitting motion. Practically rigid link does not exists. Ex : crank shaft, piston etc.,

Flexible link

A flexible link is one which undergoes partial deformation without affecting the transfer motion. Ex : ropes, belts, chains, springs etc.,

Fluid link

A fluid link is a link which has fluid inside the container and motion is transmitted through the fluid by pressure or compression. Ex: fluids used in hydraulic press, hydraulic jack, hydraulic crane etc.,

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• A joint of two links that permits relative motion is called pair.

Types of kinematic pair

1. Nature of relative motion between the links.
2. Nature of contact between the links.
3. Nature of mechanical arrangement.

Nature of relative motion

• » Sliding pair
• » Turning pair
• » Cylindrical pair
• » Rolling pair
• » Spherical pair
• » Helical pair
• Nature of contact
• » Lower pair
• » Higher pair
• Nature of mechanical constraint
• » Closed pair
• » Unclosed pair

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Sliding pair

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Turning pair

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Cylindrical pair

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Rolling pair

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Spherical pair

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Helical pair or screw pair

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Lower pair

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Higher pair

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Closed pair

• When two elements of a pair are held together mechanically, they constitute a closed pair.

Ex : All pair

Un closed pair

• When two elements of a pair are not held together mechanically, they constitute a unclosed pair.

Ex : cam and follower

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• If the last link is joined to first link to transmit definite motion, then it is known as kinematic chain.
• To determine the given assemblage of links form the kinematic chain or not:
• The two equations are: l = 2p – 4

j = (3/2) * l – 2

Where, l = number of links p = number of pairs j = number of joints

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Constrained Motions

Completely Constrained Motion

Uncompletely Constrained Motion

Successfully Constrained Motion

• Completely Constrained Motion

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Successfully Constrained Pair

Unconstrained Pair

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• The method of obtaining different mechanisms by fixing different links in a kinematic chain, is known as inversion of the mechanism.

Kinematic Chain

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Four bar chain

Slider crank chain

Double crank chain

Inversion Of Four Bar Chain

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Beam Engine

Coupled Locomotive Wheels

Watt’s Indicator Mechanism

Pantograph

First Inversion

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Second Inversion

Third Inversion

BEAM ENGINE

Coupling rod of locomotive

Watt’s Indicator Mechanism

Pantograph

Beam engine

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Coupling rod of a locomotive

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Watt’s indicator mechanism

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Pantograph

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Reciprocating engine

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1/7/2017

SINGLE SLIDER CRANK CHAIN

Whitworth quick return mechanism

Rotary or Gnome engine

Crank and slotted lever mechanism

Oscillating cylinder engine

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Bull engine

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First Inversion

Reciprocating engine

Third

Inversion

Whitworth quick return mechanism

Second

Inversion

Rotary engine

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Oscillating cylinder engine

Crank and slotted lever mechanism

Fourth Inversion

Bull Engine

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• Reciprocating engine

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• Whitworth Quick Return Mechanism

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• Rotary Engine

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• Oscillating Cylinder Engine

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• Crank and Slotted lever Quick return Mechanism

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• Pendulum pump or bull engine

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Double Slider Crank Chain

Elliptical Trammel

Scotch Yoke Mechanism

Oldham Coupling

Elliptical Trammel

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Scotch Yoke Mechanism

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Oldham's Coupling

By - Mr. H.J.Ahire

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• Oldham's Coupling

Geneva Mechanism

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COMMON MECHANISM

Ackermann Steering Mechanism

Bicycle rear wheel sprocket mechanism Foot operated air pump mechanism

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Application of the Geneva drive

• One is movie projectors : the film does not run continuously through the projector. Instead, the film is advanced frame by frame, each frame standing still in front of the lens for 1/24 of a second

ACKERMANN STEERING

By - Mr. H.J.Ahire

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THANK YOU