2. CLUTCHES
A clutch is a mechanism for transmitting
rotation, which can be engaged and
disengaged. Clutches are useful in devices
that have two rotating shafts. In these
devices, one shaft is typically driven by a
motor or pulley, and the other shaft drives
another device. In a drill, for instance, one
shaft is driven by a motor, and the other drives
a drill chuck. The clutch connects the two
shafts so that they can either be locked
together and spin at the same speed
(engaged), or be decoupled and spin at
4. TYPES OF CLUTCHES
Multiple plate friction clutch
Vehicular
Wet and dry
Automobiles
Non-power train in automobiles
Motorcycles
Centrifugal
5. MULTIPLATE FRICTION
CLUTCH
This type of clutch has several driving
members interleaved with several driven
members. It is used in motorcycles,
automatic transmissions and in some
diesel locomotives with mechanical
transmission. It is also used in some
electronically controlled all-wheel drive
systems. It is the most common type of
clutch on modern types of vehicles.
6. VEHICULAR
There are different designs of vehicle
clutch, but most are based on one or
more friction discs, pressed tightly
together or against a flywheel using
springs. The friction material varies in
composition depending on whether the
clutch is dry or wet, and on other
considerations. Friction discs once
contained asbestos, but this has been
largely eliminated. Clutches found in
heavy duty applications such as trucks
and competition cars use ceramic
clutches that have a greatly increased
7. However, these have a "grabby" action and are
unsuitable for road cars. The spring pressure is released
when the clutch pedal is depressed thus either pushing
or pulling the diaphragm of the pressure plate,
depending on type, and the friction plate is released and
allowed to rotate freely.
When engaging the clutch, the engine speed may need
to be increased from idle, using the manual throttle, so
that the engine does not stall (although in some cars,
especially diesels, there is enough torque at idling speed
that the car can move; this requires fine control of the
clutch). However, raising the engine speed too high
while engaging the clutch will cause excessive clutch
plate wear. Engaging the clutch abruptly when the
engine is turning at high speed causes a harsh, jerky
start. This kind of start is necessary and desirable in
9. Wet and dry
A 'wet clutch' is immersed in a cooling
lubricating fluid, which also keeps the
surfaces clean and gives smoother
performance and longer life. Wet
clutches, however, tend to lose some
energy to the liquid. A 'dry clutch', as the
name implies, is not bathed in fluid. Since
the surfaces of a wet clutch can be
slippery (as with a motorcycle clutch
bathed in transmission oil), stacking
multiple clutch disks can compensate for
the lower coefficient of friction and so
10. Automobiles
This plastic pilot shaft
guide tool is used to
align the clutch disk
as the spring-loaded
pressure plate is
installed. The
transmission's drive
splines and pilot shaft
have an identical
shape. A number of
such devices fit
various makes and
models of drivetrains
12. In a car the clutch is operated by the left-
most pedal using a hydraulic or cable
connection from the pedal to the clutch
mechanism. On older cars the clutch would
be operated by a mechanical linkage. Even
though the clutch may physically be located
very close to the pedal, such remote means
of actuation are necessary to eliminate the
effect of vibrations and slight engine
movement, engine mountings being flexible
by design. With a rigid mechanical linkage,
smooth engagement would be near-
impossible, because engine movement
inevitably occurs as the drive is "taken up."
14. A manual transmission contains cogs for
selecting gears. These cogs have
matching teeth, called dog teeth, which
means that the rotation speeds of the
two parts have a synchronizer, a device
that uses frictional contact to bring the
two parts to the same speed, and a
locking mechanism called a blocker ring
to prevent engagement of the teeth (full
movement of the shift lever into gear)
until the speeds are synchronized.
15. Non-powertrain in automobiles
There are other clutches found in a car. For
example, a belt-driven engine cooling fan may
have a clutch that is heat-activated. The driving
and driven elements are separated by a silicone-
based fluid and a valve controlled by a bimetallic
spring. When the temperature is low, the spring
winds and closes the valve, which allows the fan
to spin at about 20% to 30% of the shaft speed. As
the temperature of the spring rises, it unwinds and
opens the valve, allowing fluid past the valve
which allows the fan to spin at about 60% to 90%
of shaft speed depending on whether it's a regular
or heavy-duty clutch. There are also electronically
engaged clutches (such as for an air conditioning
16. MOTORCYCLES
On most motorcycles, the clutch is operated by
the clutch lever, located on the left handlebar. No
pressure on the lever means that the clutch
plates are engaged (driving), while pulling the
lever back towards the rider will disengage the
clutch plates, allowing the rider to shift gears.
Motorcycle clutches are usually made up of a
stack of alternating plain steel and friction plates.
One type of plate has lugs on its inner diameter
that key it to the engine crankshaft, while the
other type of plate has lugs on its outer diameter
that key it to a basket that turns the transmission
input shaft. The plates are forced together by a
set of coil springs when the clutch is engaged.
Racing motorcycles often use slipper clutches to
eliminate the effects of engine braking.
17. CENTRIFUGAL CLUTCH
centrifugal clutch
is a clutch that
uses centrifugal
force to connect
two concentric
shafts, with the
driving shaft
nested inside the
driven shaft.
18. WORKING OF CENTRIFUGAL
CLUTCH
The input of the clutch is connected to the
engine crankshaft while the output may drive
a shaft, chain, or belt. As engine RPM
increases, weighted arms in the clutch swing
outward and force the clutch to engage. The
most common types have friction pads or
shoes radially mounted that engage the
inside of the rim of a housing. On the centre
shaft there are an assorted amount of
extension springs, which connect to a clutch
shoe. When the centre shaft spins fast
enough, the springs extend causing the clutch
19. It can be compared to a drum brake in reverse.
This type can be found on most home built karts,
lawn and garden equipment, fuel powered model
cars and low power chainsaws. Another type used
in racing karts has friction and clutch disks stacked
together like a motorcycle clutch. The weighted
arms force these disks together and engage the
clutch
When the engine reaches a certain RPM, the
clutch activates, working almost like a continuously
variable transmission. As the load increases the
rpm drops, disengaging the clutch, letting the rpm
rise again and reengaging the clutch. If tuned
properly, the clutch will tend to keep the engine at
or near the torque peak of the engine. This results
20. Centrifugal clutches are often used in
mopeds, underbones, lawnmowers,
go-karts, chainsaws, and mini bikes to:
keep the internal combustion engine from
stalling when the blade is stopped abruptly
disengage load during starting and idle
Thomas Fogarty, who also invented the
balloon catheter, is most often credited with
first inventing the centrifugal clutch in the
1940s, although automobiles were being
manufactured with centrifugal clutches as
early as 1936.
21. CONE CLUTCH
A cone clutch serves the same purpose as a disk or
plate clutch. However, instead of mating two spinning
disks, the cone clutch uses two conical surfaces to
transmit torque by friction.
The cone clutch transfers a higher torque than plate or
disk clutches of the same size due to the wedging
action and increased surface area.
Cone clutches are generally now only used in low
peripheral speed applications although they were once
common in automobiles and other combustion engine
transmissions.
They are usually now confined to very specialist
transmissions in racing, rallying, or in extreme off-road
vehicles, although they are common in power boats.
This is because the clutch doesn't have to be pushed
in all the way and the gears will be changed quicker.
22. DIAGRAM OF CONE CLUTCH
1-Cones: female cone
(green), male cone(blue)
2-Shaft: male cone is
sliding on splines.
3-Friction material: usually
on female cone, here on
male cone
4-Spring: brings the male
cone back after using the
clutch control
5-Clutch control:
separating both cones by
pressing
6-Rotating direction: both
23. Other clutches
Dog clutches
Torque limiter or Safety clutch: This device allows
a rotating shaft to "slip" when higher than normal
resistance is encountered on a machine. An
example of a safety clutch is the one mounted on
the driving shaft of a large grass mower. The
clutch will "slip" or "give" if the blades hit a rock,
stump, or other immobile object.
Overrunning clutch or freewheel
Hydraulic clutch
Electromagnetic clutch
E-Clutch
24. DOG CLUTCHES
A dog clutch is a type
of clutch that couples
two rotating shafts or
other rotating
components not by
friction but by
interference. The two
parts of the clutch are
designed such that
one will push the
other, causing both to
rotate at the same
speed and will never
25. Dog clutches
Dog clutches are used where slip is
undesirable and/or the clutch is not used to
control torque. Without slippage, dog
clutches are not affected by wear in the
same way that friction clutches are.
Dog clutches are used inside manual
automotive transmissions to lock different
gears to the rotating input and output
shafts. A synchromesh arrangement
ensures smooth engagement by matching
the shaft speeds before the dog clutch is
26. Dog clutches
A good example of a simple dog
clutch can be found in a
Sturmey-Archer bicycle hub
gear, where a sliding cross-
shaped clutch is used to lock
the driver assembly to different
parts of the planetary geartrain.
27. Torque Limiter
A torque limiter is an automatic device that
protects mechanical equipment, or its work,
from damage by mechanical overload. A
torque limiter may limit the torque by slipping
(as in a friction plate slip-clutch), or uncouple
the load entirely (as in a shear pin). The
action of a torque limiter is especially useful
to limit any damage due to crash stops and
jams.
Torque limiters may be packaged as a shaft
coupling or as a hub for sprocket or sheave.
A torque limiting device is also known as an
28. TYPES OF TORQUE LIMITOR
Disconnect types
Shear pin
Synchronous magnetic
Ball detent
Pawl and spring
Torque limiting types
Friction plate
Magnetic particle
Magnetic hysteresis
29. Slipper Clutch
A slipper clutch (also known as a slider clutch
or back-torque limiter) is a specialized clutch
developed for performance oriented motorcycles
to mitigate the effects of engine braking when
riders decelerate as they enter corners.
Slipper clutches have been used in most high
displacement four stroke racing motorcycles
since the early 1980s. Slipper clutches were
introduced in the 1970s by John Gregory and TC
Christenson on "Hogslayer" the most successful
drag racing motorcycle of the 70s. Made of
bronze sintered plates from an earthmover and a
Rambler 2 speed transmission, the drivetrain let
30. WORKING
They are designed to partially disengage or "slip" when
the rear wheel tries to drive the engine faster than it
would run under its own power. The engine braking
forces in conventional clutches will normally be
transmitted back along the drive chain causing the rear
wheel to hop, chatter or lose traction. This is especially
noted on larger displacement four-stroke engines,
which have greater engine braking than their two-stroke
or smaller displacement counterparts.
Slipper clutches eliminate this extra loading on the rear
suspension giving riders a more predictable ride and
minimize the risk of over-reving the engine during
downshifts. Slipper clutches can also prevent a
catastrophic rear wheel lockup in case of engine
31. USES:
Slipper clutches were also used in the Honda
Interceptor 750 . Before long slipper clutches could
be found in nearly every big bore four-stroke race
bike, and notably (due to the cruiser-style and riding
position) the 1983-1985 Honda Shadow
VT750/VT700 models. Another street bike application
was in the 1990-1997 Suzuki VX800. Slipper
clutches are now gradually being factory installed on
production motorcycles such as the Aprilia RSV Mille,
Ducati 1198, Honda CBR1000RR 2008+, Yamaha
YZF-R6 2006-2008, Yamaha YZF-R1 SP 2006 ,
Yamaha YZF-R1 2007-2009, Yamaha V-Max 2009,
Kawasaki ZX-10R, Kawasaki ZX-6R, Suzuki SV1000
and GSX-R1000 2005-2007, Suzuki Hayabusa 2008,
Suzuki RM125 2008, Harley Davidson V-Rod VRSC
33. Magnetic Particle Clutch
A magnetic particle clutch is a special
type of electromagnetic clutch which
does not use friction plates. Instead, it
uses a fine powder of magnetically
susceptible material (typically stainless
steel) to mechanically link an otherwise
free wheeling disc attached to one shaft,
to a rotor attached to the other shaft
34. WORKING:
When a magnetic field is applied to the powder, it
forms chains connecting the disc and rotor. The
strength of the chains depends on the strength of
the magnetic field.
Some advantages over friction plate
clutch is:
it doesn't exhibit stick-slip phenomenon or stiction
the torque may be easily and quickly controlled
it is more resistant to wear
may be used for continuous slip applications
has a very fast response time
38. Fluid Coupling
A fluid coupling is a hydrodynamic device
used to transmit rotating mechanical
power. It has been used in automobile
transmissions as an alternative to a
mechanical clutch. It also has widespread
application in marine and industrial
machine drives, where variable speed
operation and/or controlled start-up without
shock loading of the power transmission
system is essential.
40. History
The fluid coupling originates from the work of Dr.
Hermann Föttinger, who was the chief designer at the
Vulcan Works in Stettin. His patents from 1905 covered
both fluid couplings and torque converters.
In 1930 Harold Sinclair, working with the Daimler company,
devised a transmission system using a fluid coupling and
planetary gearing for buses in an attempt to mitigate the
lurching he had experienced while riding on London buses
during the 1920s.
In 1939 General Motors Corporation introduced
Hydramatic drive, the first fully automatic automotive
transmission system installed in a mass produced
automobile. The Hydramatic employed a fluid coupling.
The first Diesel locomotives using fluid couplings were also
.
41. Overview
A fluid coupling consists of three components,
plus the hydraulic fluid:
The housing, (which must have an oil tight
seal around the drive shafts) - contains the
fluid and turbines. (also known as the shell)
Two turbines (fan like components):
One connected to the input shaft; known as the
pump or impellor, primary wheel input turbine
The other connected to the output shaft, known as
the turbine, output turbine, secondary wheel or
runner
42. Stall speed
Stall speed
An important characteristic of a fluid
coupling is its stall speed. The stall
speed is defined as the highest speed at
which the pump can turn when the
output turbine is locked and maximum
input power is applied. Under stall
conditions all of the engine's power
would be dissipated in the fluid coupling
as heat, possibly leading to damage.
43. SLIP
A fluid coupling cannot develop output
torque when the input and output
angular velocities are identical.Hence a
fluid coupling cannot achieve 100
percent power transmission efficiency.
Due to slippage that will occur in any
fluid coupling under load, some power
will always be lost in fluid friction and
turbulence, and dissipated as heat.
44. Hydraulic fluid
As a fluid coupling operates kinetically,
low viscosity fluids are
preferred.Generally speaking, multi-
grade motor oils or automatic
transmission fluids are used. Increasing
density of the fluid increases the amount
of torque that can be transmitted at a
given input speed.
45. Hydrodynamic braking
Fluid couplings can also act as
hydrodynamic brakes, dissipating
rotational energy as heat through
frictional forces (both viscous and
fluid/container). When a fluid coupling is
used for braking it is also known as a
retarder.
47. Industrial
Fluid couplings are used in many
industrial application involving
rotational power, especially in
machine drives that involve high-
inertia starts or constant cyclic
loading.
49. Automotive
In automotive applications, the pump
typically is connected to the flywheel of
the engine—in fact, the coupling's
enclosure may be part of the flywheel
proper, and thus is turned by the
engine's crankshaft. The turbine is
connected to the input shaft of the
transmission. While the transmission is
in gear, as engine speed increases
torque is transferred from the engine to
the input shaft by the motion of the fluid,
propelling the vehicle. In this regard, the
behaviour of the fluid coupling strongly
50. Aviation
The most prominent use of fluid
couplings in aeronautical applications
was in the Wright turbo-compound
reciprocating engine, in which three
power recovery turbines extracted
approximately 20 percent of the energy
or about 500 horsepower (370 kW) from
the engine's exhaust gases and then,
using three fluid couplings and gearing,
converted low-torque high-speed turbine
rotation to low-speed, high-torque output
