science

Clutch

Clutch is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Clutch rather than just read about it. In short: 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 the work.

Key takeaways

Clutch belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Clutch to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Clutch from memory before moving on to harder problems.

Reference excerpt

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 the work. In a motor vehicle, the clutch acts as a mechanical linkage between the engine and transmission. By disengaging the clutch, the engine speed (RPM) is no longer determined by the speed of the driven wheels. Another example of clutch usage is in electric drills. The clutch's input shaft is driven by a motor and the output shaft is connected to the drill bit (via several intermediate components). The clutch allows the drill bit to either spin at the same speed as the motor (clutch engaged), spin at a lower speed than the motor (clutch slipping) or remain stationary while the motor is spinning (clutch disengaged).

Types

Dry clutch

A dry clutch uses dry friction to transfer power from the input shaft to the output shaft, for example a friction disk presses against a car engine's flywheel by a spring mechanism. The wheels of the vehicle are only powered when the flywheel is in contact with the friction disk. To stop the transfer of power, the friction disk is moved away from the flywheel by means of a lever mechanism. The majority of automotive clutches on manual transmissions are dry clutches. Slippage of a friction clutch (where the clutch is partially engaged but the shafts are rotating at different speeds) is sometimes required, such as when a motor vehicle accelerates from a standstill; however, the slippage should be minimised to avoid increased wear rates. In a pull-type clutch, pressing the pedal pulls the release bearing to disengage the clutch. In a push-type clutch, pressing the pedal pushes the release bearing to disengage the clutch. A multi-plate clutch consists of several friction plates arranged concentrically. In some cases, it is used instead of a larger diameter clutch. Drag racing cars use multi-plate clutches to control the rate of power transfer to the wheels as the vehicle accelerates from a standing start. Some clutch disks include springs designed to change the natural frequency of the clutch disc, in order to reduce NVH within the vehicle. Also, some clutches for manual transmission cars use a clutch delay valve to avoid abrupt engagements of the clutch.

Wet clutch In a wet clutch, the friction material sits in an oil bath (or has flow-through oil) which cools and lubricates the clutch. This can provide smoother engagement and a longer lifespan of the clutch; however, wet clutches can have a lower efficiency due to some energy being transferred to the oil. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in engine oil), stacking multiple clutch discs can compensate for the lower coefficient of friction and so eliminate slippage under power when fully engaged. Wet clutches often use a composite paper material.

Centrifugal clutch

A centrifugal clutch automatically engages as the speed of the input shaft increases and disengages as the input shaft speed decreases. Applications include small motorcycles, motor scooters, chainsaws, and some older automobiles.

Cone clutch

A cone clutch is similar to dry friction plate clutch, except the friction material is applied to the outside of a conical shaped object. This conical shape allows wedging action to occur during engagement. A common application for cone clutches is the synchronizer ring in a manual transmission.

Dog clutch

A dog clutch is a non-slip design of clutch which is used in non-synchronous transmissions.

Single-revolution clutch

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Clutch

Start with the simplest possible case. Write down what Clutch claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Clutch before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Clutch ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Clutch

In research: Clutch appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Clutch in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Clutch is common in secondary-school and first-year university syllabi. It links to neighbouring topics Automotive transmission technologies, Clutches, so understanding it makes those chapters shorter.
In everyday life: Look for Clutch outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Clutch in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Clutch means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Clutch out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Clutch in simple terms?

Why does Clutch matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Clutch?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Clutch.