A centrifugal clutch is an automatic
clutch
A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...
that uses
centrifugal force
Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...
to operate. The output shaft is disengaged at lower rotational speed and engages as the output increases to a certain speed. 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. Historically, the term exclusively meant a similar vehicle with both bicycle pedals and a motorcycle eng ...
s,
underbones,
lawn mower
A lawn mower (also known as a grass cutter or simply mower, also often spelled lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a lawn, grass surface to an even height. The height of the cut grass may be fixed by ...
s,
go-kart
A go-kart, also written as go-cart (often referred to as simply a kart), is a type of small sports car, close wheeled car, open-wheel car or quadracycle. Go-karts come in all shapes and forms, from non-motorised models to high-performanc ...
s,
chainsaw
A chainsaw (or chain saw) is a portable handheld power saw, power saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar.
Modern chainsaws are typically gasoline or electric and are used in activities such as t ...
s,
mini bikes, 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 harnes ...
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 or capacity, its shape, or its ability to carry boats.
Small boats are typically used on inland waterways s ...
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 ge ...
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 hydrodynamics, hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power. ,
torque converter
A torque converter is a device, usually implemented as a type of fluid coupling, that transfers rotating power from a prime mover, like an internal combustion engine, to a rotating driven load. In a vehicle with an automatic transmission, the ...
and
automated manual transmission
The automated manual transmission (AMT) is a type of transmission (mechanics), transmission for motor vehicles. It is essentially a conventional manual transmission equipped with automatic actuation to operate the clutch and/or shift Gear train ...
s.
Operation
The input of the clutch is connected to the engine
crankshaft
A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...
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 r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines.
One revolution per minute is equivalent to hertz.
Standards
ISO 80000-3:2019 de ...
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 Brake shoe, shoes or Brake pad, pads that press outward against a rotating bowl-shaped part called a brake drum.
The term ''drum brake'' usually means a brake in which shoes press o ...
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 speed, the clutch activates, working somewhat like a
continuously variable transmission
A continuously variable transmission (CVT) is an automated Transmission (mechanical device), transmission that can change through a continuous range of gear ratios, typically resulting in better fuel economy in gasoline applications. This contr ...
. 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'' 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 t ...
cars featured automatic (centrifugal) clutches beginning in 1936.
, 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 position ...
, is credited with inventing a centrifugal clutch for small motor applications in the 1940s.
Principle
This works on th
principleof 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
*
Saxomat
References
External links
*Centrifugal Clutch Design , in 2021 b
Automobile InformerCompliant Centrifugal Clutches: Design, Analysis, and Testing
Master's thesis at th
Harold B. Lee Library
Brigham Young University
{{DEFAULTSORT:Centrifugal Clutch
Clutches