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A centrifugal clutch is an automatic
principle
of centrifugal force, which means when engine speed reaches a specific rpm (Revolutions per minute) it generates enough centrifugal force inside the clutch which results in clutch engagement and it transmits the engine power. At lower speeds, it disconnects itself to stop power transmission.
Automobile InformerCompliant Centrifugal Clutches: Design, Analysis, and Testing
Master's thesis at th
Harold B. Lee Library
Brigham Young University {{DEFAULTSORT:Centrifugal Clutch Clutches
A centrifugal clutch is an automatic clutch
A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
that uses centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is paralle ...
to operate. The output shaft is disengaged at low rotational speed and engages more as speed increases. It is often used in moped
A moped ( ) is a type of small motorcycle, generally having a less stringent licensing requirement than full motorcycles or automobiles. The term used to mean a similar vehicle except with both bicycle pedals and a motorcycle engine. Mopeds typic ...
s, underbone
An underbone is a type of motorcycle that uses structural tube framing with an overlay of plastic or non-structural body panels and contrasts with monocoque or unibody designs where pressed steel serves both as the vehicle's structure and bodyw ...
s, lawn mower
A lawn mower (also known as a mower, grass cutter or lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but g ...
s, go-kart
A go-kart, also written as go-cart (often referred to as simply a kart), is a type of sports car, close wheeled car, open-wheel car or quadracycle. Go-karts come in all shapes and forms, from non-motorised models to high-performance Kart rac ...
s, chainsaw
A chainsaw (or chain saw) is a portable gasoline-, electric-, or battery-powered saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. It is used in activities such as tree felling, limbing, bucking, pruning, ...
s, mini bike
A minibike is a two-wheeled, motorized, off-highway recreational vehicle popularized in the 1960s and 1970s, but available continuously from a wide variety of manufacturers since 1959. Their off-highway nature and (in many countries) typically enti ...
s, and some paramotor
Paramotor is the generic name for the harness and propulsive portion of a powered paragliding, powered paraglider ("PPG"). There are two basic types of paramotors: foot launch and wheel launch.
Foot launch models consist of a frame with harness ...
s and boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats.
Small boats are typically found on inl ...
s to keep the engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...
from stalling when the output shaft is slowed or stopped abruptly, and to remove load when starting and idling. It has been superseded for automobile applications by the fluid coupling
A fluid coupling or hydraulic coupling is a hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power.
and automated manual transmission
The automated manual transmission (AMT) is a type of transmission for motor vehicles. It is essentially a conventional manual transmission but uses automatic actuation to operate the clutch and/or shift between gears.
Many early versions of t ...
s.
Operation
The input of the clutch is connected to the enginecrankshaft
A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
while the output may drive a shaft, chain, or belt. As engine revolutions per minute
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.
Standards
ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
increase, 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 center shaft, there is an assorted number of extension springs, which connect to a clutch shoe. When the central shaft spins fast enough, the springs extend causing the clutch shoes to engage the friction face. It can be compared to a drum brake
A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum.
The term ''drum brake'' usually means a brake in which shoes press on the inner surfac ...
in reverse. This type can be found on most home-built karts
Kart racing or karting is a road racing variant of motorsport with open-wheel, four-wheeled vehicles known as go-karts or shifter karts. They are usually raced on scaled-down circuits, although some professional kart races are also held on f ...
, lawn and garden equipment, fuel-powered model cars, and low power chainsaws
A chainsaw (or chain saw) is a portable gasoline-, electric-, or battery-powered saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. It is used in activities such as tree felling, limbing, bucking, pruning, ...
.
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 speed, the clutch activates, working somewhat like a continuously variable transmission
A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. T ...
. As the load increases, the speed drops, disengaging the clutch, letting the speed rise again, and reengaging the clutch. If tuned properly, the clutch will tend to keep the speed at or near the torque peak of the engine. This results in a fair bit of waste heat
Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
, but over a broad range of speeds, it is much more useful than a direct drive in many applications.
History
Centrifugal clutches were used in railway locomotives before 1858, and referred to (in relation to electric motors) in a patent of 1899. A patent was issued in the United States for an automotive centrifugal clutch (on an electric vehicle) in 1898. There is a design for a toy 'automatic clutch' in ''Meccano Magazine
''Meccano Magazine'' was an English monthly hobby magazine published by Meccano Ltd between 1916 and 1963, and by other publishers between 1963 and 1981. The magazine was initially created for Meccano builders, but it soon became a general hobb ...
'' of June 1934.
Armstrong Siddeley
Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines.
The company was created following ...
cars featured automatic (centrifugal) clutches beginning in 1936.
Thomas Fogarty
Dr. Thomas J. "Tom" Fogarty (born February 25, 1934 in Cincinnati, Ohio) is an American surgeon and medical device inventor. He is best known for the invention of the embolectomy catheter (or balloon catheter), which revolutionized the treatment o ...
, who is also credited with inventing the balloon catheter
A balloon catheter is a type of "soft" catheter with an inflatable "balloon" at its tip which is used during a catheterization procedure to enlarge a narrow opening or passage within the Human body, body. The deflated balloon catheter is positione ...
, is credited with inventing a centrifugal clutch for small motor applications in the 1940s.
Principle
This works on thprinciple
of centrifugal force, which means when engine speed reaches a specific rpm (Revolutions per minute) it generates enough centrifugal force inside the clutch which results in clutch engagement and it transmits the engine power. At lower speeds, it disconnects itself to stop power transmission.
See also
* SaxomatReferences
External links
*Centrifugal Clutch Design , in 2021 bAutomobile Informer
Master's thesis at th
Harold B. Lee Library
Brigham Young University {{DEFAULTSORT:Centrifugal Clutch Clutches