Universal Collage of Engineering
&
Technology
SIDDHANT BHAVSAR 130460119011
JAYESH BHOJWANI 130460119012
AKSHAR CHAUHAN 130460119015
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.