fly·wheel | \ˈflī-ˌhwēl, -ˌwēl \

Definition of flywheel 

: a heavy wheel for opposing and moderating by its inertia any fluctuation of speed in the machinery with which it revolves also : a similar wheel used for storing kinetic energy (as for motive power)

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A heavy wheel attached to a rotating shaft, a flywheel smooths out delivery of power from a motor to a machine. The inertia of the flywheel moderates fluctuations in the speed of the engine and stores the excess energy for intermittent use. In automobile engines, the flywheel smooths out the pulses of energy provided by combustion in the cylinders, and provides energy for the compression stroke of the pistons. In power presses, the punching, shearing, and forming are done in a fraction of the operating cycle. During the rest of the cycle, the speed of the flywheel is built up by a comparatively low-powered motor, and most of the required energy for the cycle is provided by the flywheel.

Examples of flywheel in a Sentence

Recent Examples on the Web

Although economic flywheels played an important role, the story of how the internet became centralised is more complex. The Economist, "More knock-on than networkThe story of the internet is all about layers," 28 June 2018 As a boat rolls, the angular momentum of the flywheel creates a reaction force that transmits through the mounts to the hull of the boat. Dan Neil, WSJ, "Skip the Seasickness: How Boats Are Getting More Tech-Savvy," 28 June 2018 The resulting rotation engages the flywheel, turning the engine over. Kevin Dupzyk, Popular Mechanics, "Watch Us Take Apart a Chainsaw Into 297 Pieces," 24 June 2015 McCloskey's 1920 Rumely Oil Pull tractor has to be started with a large flywheel on its side. Mitchell Kirk, Post-Tribune, "Cass County man collects tractors from around the world," 6 July 2018 The flywheels come in various sizes for monohull boats (sorry, no catamarans) from 25 feet to more than 85 feet long. Jack Stewart, WIRED, "Seakeeper’s Super Spinning System Keeps Ships Stable at Sea," 21 May 2018 Current satellites often rely on a type of flywheel called a reaction wheel. David Grossman, Popular Mechanics, "Magnetic Engines Could Help Satellites Stay in Orbit Longer," 25 July 2016 Amazon’s frugality and high-tech investments in logistics create what analysts call a flywheel of ever-declining prices and delivery times. David Whelan,, "What Amazon & Co. should fix first in our health care system," 27 Mar. 2018 From printing presses to the mechanics of manufacturing, the flywheel fostered our intellect and enabled our industry. Bailey Loosemore, The Courier-Journal, "Everything you want to know about Flywheel Brewing, a craft brewery in Kentucky," 4 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'flywheel.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of flywheel

1784, in the meaning defined above

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fly whisk



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Last Updated

16 Sep 2018

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Time Traveler for flywheel

The first known use of flywheel was in 1784

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English Language Learners Definition of flywheel

: a heavy wheel that is part of a machine and that controls the speed of machinery

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evasion of direct action or statement

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