Simple mechanism

SIDDHANT BHAVSAR 130460119011

JAYESH BHOJWANI 130460119012

AKSHAR CHAUHAN 130460119015

Universal Collage of Engineering&

Technology

Kinematics : This is branch of science which deals with the relative motion between various parts of machine, neglecting a forces.

Kinetics : This is branch of science which deals with the forces arising due to inertia of moving parts of a machine or mechanism

Types of Links :

Binary Joint : When two links are joined at the same connection, the joint is known as binary joint

Ternary Joint : When three links are joined at the same connection, the joint is known as binary joint.

Quaternary Joint : When four links are joined at the same connection, the joint is known as binary joint.

Classification of Links :

Rigid link : A link which dose not undergo any deformation during transmitting

motion is known as rigid link, For Ex. Connecting rod, crank, tappet rod etc.

Flexible link : A link which is partially deformed in a manner not to affect the transmission of motion, is known as flexible link. For Ex. Belts, ropes, chains, springs etc.

Fluid link : A link which is deformed by having a fluid in a closed vessel and the motion is transmitted through the flied by pressure is known as flied link. Hydraulic press, hydraulic jack and fluid brake are the example of fluid link.

Floating link : A link which not connected to frame, known as floating link.

Classification of Kinematic Links :

Kinematic pairs may be classified according to the :

Type of relative motion

Type of contact

Type of mechanical constraint

Kinematic pairs according to the relative motion:

Sliding pair : When two links(elements) have a sliding motion relative to another, the kineatic pair is known as sliding.

Turning pair : When one links(elements) is revolve or turn with respect to the axis of first link, the kinematic pair formed by that two link is known as turning pair.

Rolling pair : When two links is roll on another fixed link, the kinematic pair formed by that two link is known as rolling pair.

Screw pair : When two links is turn on second link by means of thread, the kinematic pair formed by the two link is known as screw pair.

Spherical pair : When two links(element) is turn in spherical manner on second link, the kinematic pair Formby that two links is known as spherical pair.

Kinematic pairs according to the type of contact :

Lower pair : When the two links(element) of a pair have surface(or area)contact during motion and the relative motion between two links is purely turning or sliding, the pair is called a lower pair.

Higher pair : When the two links(element) of a pair have point or line contact during motion and the relative motion between them is a combination of sliding and turning, then

the pair is known as a higher pair.

Kinematic pairs according to the type of mechanical constraint:

Close pair : When the two links(element) of a pair are in contact by means of any mechanical arrangements, they are called a closed pair.

Unclose pair : When the two links(element) of a pair are in contact due to force of gravity or due to spring action. The pair is called an unclosed pair, for example, the cam and spring loaded follower pair.

Type of motions :

Completely constrained motion : When the motion a

pair is irrelative to the direction of force, and takes place only in a single definite direction , then it is called a completely constrained motion.

Incompletely constrained motion : When the

motion a pair is more than one direction, it is called as incompletely constrained motion.

Successfully constrained motion : When the motion a

pair is converted to completely constrained motion by some other means, called as successfully constrained motion.

Kinematic chain: When number of links connected in such a manner they have relative motion as well as last link end is connected to first link end is know as chain.

For a kinematic chain N = 2p-4 =2( j +2 )/3 Where N = no of links p = no of joints. Where LHS > RHS , then the chain is looked LHS = RHS , then the chain is constrained LHS < RHS , then the chain is unconstrained.

Inversion Of Mechanism: When the number of links in kinematic chain is more then three the chain is known as mechanism. When one of the kinematic chain at a time is fixed , given the different mechanism of the kinematic chain.

The inversion of mechanism may be classified as ;

Inversion of four bar chain

Inversion of single slider crank chain

Inversion of double slider crank chain

Inversion of four bar chain : This is a simple

types of kinematic chain in which four rigid links are connected by four pinpoints. The four bar chain has four turning pairs. Link 1 & 2 forms turning pair, link 2 & 3 forms second turning pair, link 3 & 4 form third turning pair and link 4 & 1 from fourth turning pair. A link which can make complete revolution is known as crank.

Coupled wheel of a locomotive : In a four bar chain ABCD , link AD is

fixed and link AB behaves as crank. Length of AB and CD are equal. Length of link AD and BC are equal, among which link AD is fixed and link BC behaves as a connecting rod. As link AB rotates the link CD also rotate. This mechanism transmits rotary motion from one link to other. This is also called double crank mechanism.

Beam engine : As shown in figure link l is fixed.

Link AB rotates about point A, the lever CE oscillate about point D. the link which is connect to piston moves the piston up and down. This is also called crank and lever mechanism.

Single slider crank chain : As shown in figure in this

mechanism there is a single sliding pair and three turning pair. The link l is fixed, link 2 is crank, link 3 is connecting rod and link 4 is piston(slider) . This mechanism convert rotary motion to reciprocating and vice-versa. In IC engine reciprocating motion converted to rotary motion by using same mechanism.

Thank You