science

Pullstring

Pullstring 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 Pullstring rather than just read about it. In short: A pullstring (pull string, pull-string), pullcord (pull cord, pull-cord), or pullchain (pull-chain, pull chain) is a string, cord, or chain wound on a spring-loaded spindle that engages a mechanism when it is pulled. It is most commonly used in toys and motorized equipment.

Key takeaways

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

Reference excerpt

A pullstring (pull string, pull-string), pullcord (pull cord, pull-cord), or pullchain (pull-chain, pull chain) is a string, cord, or chain wound on a spring-loaded spindle that engages a mechanism when it is pulled. It is most commonly used in toys and motorized equipment. More generally and commonly, a pullstring can be any type of string, cord, rope, or chain, attached to an object in some way used to pull or mechanically manipulate part of it.

Toys

Perhaps the simplest pullstring toy is the yo-yo (c. 460 BCE). The jumping jack is a more complicated animated puppet paper doll that uses a pullstring to move its arms and legs up and down. Trompos and some spinning tops use a string that is wound around the top and then pulled to make it spin. More recent toys include dolls, such as Chatty Cathy (1959), Charmin' Chatty (1963), Talking Tamu (1970), Horse from Mister Rogers' Neighborhood also known as Ino A Horse, Look Around Crissy (1972), Sky Dancers (1994), and Sheriff Woody (from the Toy Story franchise), that have a pullstring built into them that activates a speaker when it is pulled, causing the doll to say a built-in phrase. The Blythe doll (1972) has a pullstring that changes the doll's eye color. Other non-doll toys like See 'n Say (1965). In Mister Rogers’ Neighborhood episode 1627, a similar toy to a see N Say called a Speak N Spell is featured, but instead of the arrow pointing, The handles attached to the strings have the names of all the animals that are pulled to activate the sounds of the animals. The earliest patent with a pullstring included in it is an 1886 "Toy Bowling-Alley".

Engines

Many motorized lawn mowers, chainsaws, portable generators, and portable outboard motors use a pullstring or pullcord attached to a handle as a manual ignition device. Some vehicle engines are also started with pullchains, such as the early-1900s Puckridge, or pullcords, like the pre-release version of the Citroën 2CV car, and the DKW RT 125 scooter. Early jet engines such as the Junkers Jumo 004 used a Riedel two-stroke starter motor actuated by a pullcord.

Weapons Some grenades such as the German Models 24, 39, and 43 have pullcords. Some machine guns such as the M73 machine gun and M85 machine gun use a pullchain to charge and/or fire them. The Kord machine gun uses a device to cock the weapon. Various Booby trap weapons and devices have used cords/cables.

Transport

A train's emergency brake can be a cord or chain that will stop the train when pulled. Some transit buses and trams/trolleys have a pullcord, also known as a bell cord, that a passenger can pull to signal the driver that they are requesting a stop. Many newer vehicles now use buttons to request stops instead. The Jaguar XK120 sports car's doors have no external handles so it uses an interior pullcord instead.

Other Some types of window blinds and curtains use a cord pull to open, close, raise, and lower them. Some types of ladders like the extension ladder and attic ladder can have a pullstring that pulls it down from the ceiling. A dock plate can use a pullchain to move it. Some gates have a pullstring on its latch. A pull switch uses a chain or string to actuate a switch, commonly used in lighting and ceiling fans. Modern flush toilets use a pullchain attached to a lever that lifts the plunger to release water into the toilet bowl. The photoplayer uses pullchains to generate sound effects for silent films. Pre-1990s North American diesel locomotive train horns used a lever or pull cord to actuate an air valve. Older steam whistles were almost always actuated with a pull cord. Some grandfather clocks have a pullchain to raise the weights in order to wind the clock's gears. A lifejacket has a pullcord used to inflate it.

Variants A bowstring is perhaps the simplest type of pullstring that pulls a bow's ends together. A ripcord is a type of pullstring used to release a parachute. A drawstring is a type of pullstring used in many aspects of the fashion industry and in bags as a closing device.

See also Bell pull Drawer pull Drawstring Hoist (device) Pull switch

References

Illustrations

Worked examples

Example 1 — a first encounter with Pullstring

Start with the simplest possible case. Write down what Pullstring 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 Pullstring 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 Pullstring 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 Pullstring

In research: Pullstring 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 Pullstring 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: Pullstring is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chains, Household hardware, so understanding it makes those chapters shorter.
In everyday life: Look for Pullstring 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 Pullstring in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pullstring 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 Pullstring out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pullstring in simple terms?

Why does Pullstring 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 Pullstring?

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 Pullstring.