The
camshaft is one of the most important
parts of the internal combustion engine
that regulates the opening and closing
of the inlet and exhaust valves.this
article explains the camshaft
function,working,parts,and applications.
A camshaft is
a rod featuring a series of
protruding cams, designed to
transform rotary motion into
linear motion.
In the case of an
engine, a camshaft is a part of
the engine that regulates the
opening and closing of an IC
engine¡¯s inlet and exhaust
valves. A camshaft has more than
one cam. It has many radial
cams, which displace the inlet
or outlet valve. This cam slides
over the inlet and exhaust
valves.
The cam transforms the
rotary motion of the camshaft
into the reciprocating movement
of the lifter or follower. This
shaft allows the suction and
discharge of the fuel inside the
engine.
The camshaft
operation depends on the working
of the cam and the functioning
of the valve. The inlet and
outlet valves install on the
cylinder head, and cams are
installed on these valves. The
cylinder head blocks the nozzle,
which permits the fuel suction
or discharge and needs
reciprocating movement.
In simple
words, a cam is a unit that
transforms rotary motion into
linear motion and vice versa.
The cam on the camshaft achieves
displacement with a radial
turning pattern and a follower
moving vertically to the axis of
rotation. The position of the
camshaft varies according to the
design of the engine.
The main function of
the camshaft is to open the
suction valve and exhaust valve
at the appropriate time. The
crankshaft drives to this shaft.
It is linked with the crankshaft
through a belt or meshing gears.
The movement of the
camshaft is slower than the
crankshaft. It completes one
revolution after two revolutions
of the crankshaft. In a
four-stroke engine, a camshaft
works in the following way:
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As the piston moves from
TDC to BDC (downward),
it transfers its motion
to the crankshaft.
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The crank receives
piston motion and
transforms this motion
into rotary motion, and
starts rotating.
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The crankshaft is
connected to the
camshaft through a gear
or belt.
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As the crankshaft
transfers its rotary
motion to the camshaft,
the camshaft converts
this rotary motion into
reciprocating motion and
presses the inlet valve,
and opens it.
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As the valve opens, the
fuel starts to enter
the combustion chamber.
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After suction and
compression strokes, the
combusted air-fuel
mixture expands in the
chamber, which forces
the piston to move
downward.
¡¤
During the downward
motion of the piston,
again, the crankshaft
receives motion and
moves the camshaft.
¡¤
As the cam of the
exhaust valve receives
this motion, it presses
the exhaust valve and
opens it, which allows
exhaust gases to move
out of the combustion
chamber.
The solid material is most
commonly used for the
manufacturing of the camshaft.
This is because such camshafts
provide great rigidity. Cast
iron is also used for the
manufacturing of camshafts
because cast iron delivers more
strength.
The camshafts made of the
chilled iron process can provide
excellent wear resistance
because the chilling method
hardens the material. Different
materials mix with iron to
generate the most appropriate
features for their applications.
Some industries also utilize
billets when less production and
excellent quality are needed.
But this process demands high
time and cost compared to other
processes. These shafts
manufacture through machining,
casting, or forging on milling
and lathe machines. They are
manufactured by forging,
casting, and machining on lathes
and milling machines.
It is
a special type of needle bearing
or roller that follows the cam
lobe profile. It is also
called track follower. There are
different configurations of the
cam follower, but the most
important feature is the
attachment of the cam follower
to the mating part. The yoke cam
follower has a hole in the
center, and the stud cam
follower uses a stud.
In the absence of this
camshaft part, the cam is not
very useful because the cam
takes support from the follower
to convert rotatory motion to
reciprocating motion. The
followers have cam follower
bearings that enable the cam
follower to convert rotary
motion into reciprocating.
The follower bearings
also have different designs but
are usually manufactured with a
very thick outer ring. This
thick outer ring design of the
bearing permits the follower to
absorb high radial loads, while
soft cores can withstand high
loads without the risk of
component damage.
The cam follower
requires balls or needles and
special materials such as chrome
or stainless steel according to
the requirements of the
application.
¡¡
2. Cam
A cam is a device that transfers
the required movement to a
follower through direct contact.
The main objective of this
camshaft part is to transform
the crankshaft¡¯s rotary motion
into linear motion.
It has a non-circular
design with a single lobe. The
follower gets the movement by
the cam as it turns. Each
engine¡¯s camshaft has more than
one cam.
The cam is installed
on the valves. It is responsible
for regulating the opening and
closing of the intake and
exhaust valves.
The cam timing is very
important for the performance of
the IC engine. The rotation of
the cam opens the cylinder¡¯s
suction valve and exhaust valve.
The proper timing of the cam is
very important to ensure that
fuel is injected and expelled at
the right time.
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3. Main
Journal
The main objective of
the main journal is to maintain
the position of the camshaft
when it rotates around the
engine.
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4.
Lobes
The camshaft lobes
spin according to the movement
of the piston. The speed of this
component varies according to
the speed of the engine. The
main objective of the lobes is
to open and shut the inlet and
outlet valves.
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5. Ends
The front end of the
camshaft is designed in such a
way it links the belt with the
crankshaft. The cam¡¯s rear end
uses a special gear to rotate
the motor distributor. The
ignition timing is the same as
the rest components of the
engine.
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6.
Bearing
The bearing installs
with the engine main hornet. It
prevents the camshaft from
destroying the engine block if
the engine fails. The bearings
assist in maintaining perfect
camshaft rotation.
A flat tappet cam is
not flat in reality. These cams
contain a small crown on the
face. It is installed where the
lifter and lobe move oppositely
to each other, and the lifter
rotates on the lobe. The lobes
of this cam are manufactured in
a small tapered design.
The lifter must be
turned to the lobe in order to
avoid unnecessary and damaging
wear. In contrast to roller
tappets, flat tappet has low
weight and less mass. It is easy
to guess that the flat tappet is
at the dead lobe center of the
cam lobe. These cams are cheaper
than roller cams. Due to this
reason, flat cams are more
attractive.
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2)
Roller Cams
The rounded tip of the
roller cam allows the roller to
hold the valve open for extended
periods of time at high lift,
which affects fuel-air mixture
requirements. The shape of the
lobe also allows the valve to
open more quickly.
The main advantage of
these camshafts is that they
decrease inner friction, permit
a more violent cam profile, and
favor high speeds. These have
very high durability. In other
words, it has an unlimited
useful life.
Roller cams can
be reused again and again. They
reduce friction and increase
power. It also increases service
life by reducing wear and tear.
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Based on the camshaft
driver member shape
1) Cylindrical Cam
This type of cam has a
cylindrical shape. It is
also known as a barrel
of drum cam. The surface
of the cylindrical cam
has a groove cut. The
cam follower uses this
groove cut for its
motion.
This camshaft has a
cam¡¯s axis parallel to
the direction of the
follower member's
motion.
2) Radial
Cam
A radial cam is also
called a plat or disk cam. It is
known as a radial cam because it
has an axis perpendicular to the
direction of the follower's
movement.
This type of cam has
an irregular contour plate. This
plate uses to convert the motion
of the cam to the cam follower
or driven member motion.
3)
Conjugate Cam
It has 2 rollers. The
follower
or
driver
of this
camshaft
is
linked
with
these
rollers.
The
rollers
tend to
limit
the
movements
of
others
so that
they can
remove
noise
and
produce
quiet
operations.
These cams use in
applications
that
need the
quiet
working
of the
camshaft.
4)
Globoid
Cam
This cam has a very
similar
design
to a
cylindrical
cam. The
main
difference
is that
the
cylindrical
cam
replaces
via a
concave
or
convex
assembly.
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5)
Spherical Cam
The spherical cam has
a groove
on its
curved
design.
It has a
spherical
shape.
The
follower
runs
across
the
groove.
The
movement
of the
follower
is
vertical
to the
rotational
axis of
the
spherical
cam.
6)
Translating Cam
This cam contains a
grooved
contour
plate.
The
follower
members
oscillate
along
the cam
groove
surface.
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7)
Heart-shaped Cam
It is known as a
heart-shaped
cam
because
it has
asymmetrical
heart-shaped.
The
follower
runs
along
the cam
edge. It
has
smooth
and
continuous
motion.
Such a
type of
cam is
most
commonly
depleted
to wound
the
cable
across
the
solenoid
squarely.
8) Wedge
Cam
The end of this cam
has a
pointed
shape
and a
wide
basement.
The
driver
has a
sliding
movement
relative
to the
cam.
9) Spiral
Cam
It is a spiral
semi-circular
contour
that
contains
a groove
on its
surface.
The
follower
of this
cam has
a
perpendicular
movement
according
to the
driver
member's
linear
movement
of the
camshaft.
The camshaft gets driving
power by the crankshaft. The
crankshaft delivers its power to
the camshaft through different
means and drives it. The
camshaft driving mechanism is
given below:
1.
Chain Drive
2.
Gear Drive
3.
Belt Drive
1) Chain Drive Mechanism
In this
mechanism, a chain sprocket is utilized
to deliver the crankshaft power to the
camshaft.
If the distance
between the crankshaft and the camshaft
is large, a chain drive mechanism is
operated.
In this
mechanism, the camshaft and
crankshaft move in an identical
direction. It uses a chain
tensioner to prevent the chain
system from coming loose because
loose chains cannot transfer
sufficient power from the
crankshafts to the camshafts.
2) Gear Drive Mechanism
The gear drive mechanism is used
where is a required minimum
distance between the crankshaft
and camshaft. In this mechanism,
a gear drive method uses to
deliver the crankshaft¡¯s power
to the cam.
In the case of
the gear drive mechanism, the
crankshaft¡¯s driver gear meshes
with the camshaft¡¯s driven gears
(as you can see in the
below-given diagram). As the
crankshaft starts rotating, it
delivers power to the camshaft
through the driver gear. As the
driver gear rotates, it further
rotates to the driven gears,
which opens and close the inlet
and exhaust valves of the
engine.
3) Belt Drive Mechanism
The working of the belt drive
mechanism is very identical to a
chain drive mechanism. There is
only a little bit of variance
between these two mechanisms,
and a belt mechanism uses a belt
for transferring crankshafts
power to the camshafts while a
chain drive mechanism uses a
chain.
The main
function of the
camshaft is to
open the inlet
and exhaust
valve of an
engine by
converting the
rotary motion of
the crankshaft
into a
reciprocating
motion.
A
camshaft works
on which driving
mechanism?
A
camshaft
uses the
following
three
main
mechanisms
to
receive
power by
the
crankshaft:
¡¤
Belt
drive
mechanism
¡¤
Gear
drive
mechanism
¡¤
Chain
drive
mechanism
Why is a
camshaft needed
in an engine?
The piston
engines can¡¯t
work without a
camshaft. A
machine is
needed a
camshaft for the
proper opening
and closing of
the inlet and
exhaust valves.
What is
the function of
a camshaft?
The main
function of the
camshaft is to
open the inlet
and exhaust
valve of an
engine by
converting the
rotary motion of
the crankshaft
into a
reciprocating
motion.
The
camshaft
controls the
breathing of the
engine ¨C it
manages the
intake of the
air-fuel mixture
into the
cylinders for
combustion and
the expulsion of
exhaust gases
after
combustion.
What are the
applications of
a camshaft?
In reciprocating
engines, the
camshafts use to
close and open
the suction and
exhaust valves.
What are the
signs of a bad
camshaft?
1.
Engine
stalling
2.
The
vehicle
won¡¯t
start
3.
The
vehicle
moves
slowly
4.
Cylinder
misfire
5.
Poor
fuel
economy
6.
A
reduction
in the
engine
power
7.
Metal
debris
in the
engine
oil
8.
Check
engine
light
illumination
What are
the parts of
camshaft?
¡¤
Cam
lobes
¡¤
Base
circle
¡¤
Camshaft
ends
¡¤
Bearings/bearing
journals
¡¤
Lifters
What
causes a
camshaft to
fail?
¡¤
Insufficient
lubrication
¡¤
Poor
Manufacturing
¡¤
Wear and
Tear
¡¤
Wrong
Installation
¡¤
Mechanical
Over-revving
¡¤
Contaminated
oil
¡¤
Engine
Overheating
Can a car
run with a bad
camshaft?
Yes, your car
can run with a
bad camshaft,
but it¡¯s not
recommended. The
camshaft is
crucial for
opening and
closing the
engine¡¯s valves
to allow for the
intake of air
and fuel and the
expulsion of
exhaust gases.
If the camshaft
is damaged, it
can lead to poor
engine
performance or
even engine
failure.
