How a Retractable Ballpoint Pen Works

Click pens. You click them on, you click them
off. How do they work? And what creates that distinctive click? There
are many types of click-to-write pens. A simple latch mechanism
locks this ink cartridge in place; it’s released by pressing a button.
And in this pen an angled-tooth cam locks or releases the ink
cartridge. And here a triangular cam that tilts from side-to-side
to lock and release the cartridge. In this video I detail the operation
of this pen: a Parker Jotter, introduced in 1954. It’s one of
the first retractable pens. Now, listen carefully and you’ll notice
that it emits four clicks. A click when I push the button … a second
click when I release it …And then when I push the button to retract the
ink cartridge, a third click … and release… a fourth click. To
understand why these clicks occur let’s look inside. The pen’s barrel
houses an ink cartridge with the ballpoint tip, two springs—one at the
top and one at the bottom—and a plastic tube which is press
fit inside the metal barrel of the pen so that it is fixed in place. Inside
that tube is where all the action happens. A Parker Pen Company patent
describe the three parts that produce the pen’s click: the
cam body, the tubular plunger and the stop members. The cam body is affixed
to the top of the replaceable ink cartridge. During operation
this cam body rotates and slides up and down. The tubular plunger does
not rotate; it only slides up or down. The stop members are shown
as separate pieces here, but keep in mind they’re part of the press-fit
plastic tube and so never move. The pen can be in either of two
positions: the retracted, non-writing position where the tip of the
cartridge is inside the barrel. Or, in the extended, writing position
where the cartridge’s tip projects from the barrel. To see how the
plunger, cam body and stop members interact I’ve broken the cam
movements into eight steps. First, push the button to drive the plunger
and the cam body down the barrel until the top of the cam body drops
below the fixed stop members. Second, remember that the spring
at the bottom of the pen pushes the cam body up and so keeps it in
contact with the plunger. That axial spring force shoves the cam body
up the barrel, but also rotates the cam body because it mates with
the plunger at an angle. The cam body rotates 45 degrees until
it strikes the surface of the plunger. That very fast motion creates
the first click. Third, I release the button and a spring between the
plastic tube and the lip of the plunger forces it to the top of the
pen. When the tips of the plunger’s fingers clear the cam body, the
cam body rotates another 45 degrees until it strikes the blue stop members.
That’s the second click of the pen! Fourth, I release the button
completely and now the cam body remains locked in place. It cannot
rotate nor move upward and so the pen is ready to write. To retract the
pen I press the button to drive the plunger into the cam body, and to
push it past the stop members. The cam body rotates until it strikes
the plunger. That’s the third click. I release the button so the top
spring forces the plunger upward. When the plunger fingers clear the
cam body, it slides and rotates 45 degrees until it strikes into the
stop members. That’s the fourth click. Once the button is completely
released stop members slot into the cam body so that when the plunger
moves up, the cam body moves with it to retract the ink cartidge.
In extending and retracting the ink cartridge the cam body rotates 45
degrees four times — or 180 degrees total. The cam body has 180 degree
rotational symmetry so the next extend/retract cycle repeats the same
sequence of steps. This particular model of pen has sold over three-quarters
of a billion units since its debut. It took a team of sixty-six
people to design this pen. And although it’s a mechanical
marvel, the Parker company worried that this retractable ballpoint ink
pen would damage their reputation — Parker pens were fountain pens
— and so the company left off their iconic “arrow” clip. But within
four years the pen earned its arrow. And inspired other pen makers to
design click and lock mechanisms — all different to avoid patent
infringement. The clicking of a pen demonstrates how a single engineering
problem can have many engineering solutions ranging from robust,
to cost efficient, to unique. I’m Bill Hammack, the EngineerGuy.
Subscribe to the channel for more engineering videos. And if you want
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to sign up. Our advanced viewers help refine a draft
of this video in a much better product. We greatly appreciate all
of your responses. Thanks.


  • Lester004

    I used to turn my retractable pens into bb guns

  • Russell Houde

    I actually have a Parker Jotter, but it is a fountain pen not a ballpoint

  • Vivi Fu

    Hey, can you make a video to explain how those switch of, when you press it, something will jump out. Like the mechanism of small knives where you press a button and the knife jump out.

  • Shubham Kumar

    Your passion for engineering inspires me. Thanks.

  • T New

    This vid helped me repair my Parker Jotter pen. Thank you!

  • Spooky Boogie

    I'm just here to know if playing with the click screws the pen up..

  • Black Alende

    are you related to chef john? the way you both talk…LOL

  • DiXiT

    How the cam body rotates ??
    We are just pushing it down and spring forces it how cam body rotate??? Plz clarify

  • daniel s

    Brilliant channel. Super smooth and informative

  • CrossBro

    3:40 penis

  • AbdulAziz4CaNaDa

    Wow… never thought these simple things in our lives how they work. Thank you 😊

  • Luke Kline

    I remember as a kid taking apart my pen and trying to figure out how it worked; oddly fascinating video!

  • degu yit yotor

    getish enwedihalen

  • Legendary Chicken

    Awesome animation and narration! Love it

  • sam signorelli


  • MPR Colorado

    To me, it’s sort of mind-blowing and fascinating how these every-day products take enormous engineering feats! Thank you for your work!

  • Shantanu Goyal

    This is Youtube gold. This video deserves an award.

  • atlantamx3

    @EngineerGuy I'm not an engineer, but isnt it 360* of rotation and not 180*?

  • joseph jackson

    I took apart many pens to see how they work, and they all use this rotational motion in the cam shaft to retract the writing tip.

  • Mr MEMé


  • you're adopted

    i could listen to that intro all day

  • JDR

    Cant believe im going to watch this.

  • Scocasso Vegetus

    When I was in Japan, I went to a store which had a very very extensive pen section. It was so interesting to see that each pen had a different clicking mechanism (perhaps because they each had their own patent, or maybe because it's fun to design mechanism, don't know) to accomplish the same thing — I looked through those pens for an hour.

  • christian lee

    I want to see the triangular style

  • George Cowsert

    My favorite pens are the G2 Pilot pens, because they're easy to modify into pen-launchers.

    Basically, take the spring and place it between the two plastic parts that let the pen function normally. There is a little plastic ring incorporated into the body that provides just the right amount of resistance to keep the spring tense, but not stuck.
    Using a saw, cut off the tip of the pen and reattach it so that when you press the button, all the parts don't fly out but you can still load the launcher and fire it.

    Bam! Now go have fun at your local middle-school.

  • Richard Forrest

    The writing is really beautiful. "How the clicking of a pen". You should be extreamly proud of these videos. Wonderfully made.

  • french baggette

    Bro havent you ben borred in class??? I discovered that pen bullshit in 3rd grade dude

  • Nikolay Rybkin

    So they patented it but I guess this mechanism was inspired by locking methods already in use in firearms.

  • Robert Emerson

    Idk what this guy has on YouTube but his channel is the only one I've ever seen that doesn't begin with ads and the videos aren't long enough for any to interrupt them. ??

  • Robert Emerson

    This was one of the best demonstrations I've seen on this channel as I'm usually still left with questions. (That's the problem with keeping the videos so short though.) Anyway, this shows why 2 of the 4 clicks are a bit stronger and, consequently, louder than the other 2. I admit that I've taken pens apart years ago out of curiosity so I already knew how they worked. I don't believe I've seen the type that rocks back/forth though.

  • Lil Sebastian

    but why the cam body spins?

  • Jonny Nik

    This really puts into perspective how incredibly much time, planning and effort has been put into everyday objects. Looking around, I feel like we owe so much to all the engineer guys out there…

  • Cakes dont lie ?

    I have never seen the triangular one

  • TellYouWhat 95

    I love parker pens I've always had one throughout school

  • Solaire of Astora

    I don't know how this ended up on my front page but I'm happy it did

  • Manuel Silva

    Let me prise your explanation and point out another useful explanation:

  • Rise

    I never knew I needed to know this, but I hella did

  • Randomness channel

    I always loved those kind of pens. Still using to this day. Have a blue one with black ink. That confuses a lot of people. 🤣

  • Nic De Houwer

    this man is so fucking friendly. Amazing.

  • odeg

    We learnt about click pens in engineering 😂

  • Mainak Mukhopadhyay

    One of my greatest childhood mysteries solved

  • Lord Steve

    I am glad that the University of Illinois has decided to give you a diploma in Pentology!

  • Boink & No Boink

    It's 7:26 in the morning and I haven't fecking slept yet, but I must know how pen mechanisms work

  • Saurav Raj

    Why don't you be the teacher of my college .?..

  • Bushcraft North of 60

    That was so satisfying. Thanks for breaking it down.

  • Gl San

    Is this was 13th century Europe, you would be hanged for Blasphemy.

  • The Memester Gangster

    The faint laughter of fountain pen users can be heard in the distance.


    I knew I wasn't the only one obsessed with how these pens worked

  • Linktw0

    I got lost on YT and ended up here..
    So I watched the whole thing to the end and now im subbed..
    Aw Yiisss!

  • Aju Joseph Kailath

    sponsored by Gravity

  • Zurtron D

    Lol this is copied from Jared own

  • Street Tutorials. ST

    My click pen has a different cambody…

  • Hassan Raza 2

    You look like an alien!

  • Lutz Köbel

    There should be no high school or college student that does not know this question

  • Ramon Mercedes

    Watched 15 times, it's a beautiful!

  • Sohom Bhattacharjee

    please make a video on Lamy click mechanisms

  • Inigo Diaz

    I thought this was common knowledge for any middle/high schooler. What's everyone else wasting their time on?

  • Super120

    lol i just noticed it today in school and this is in my recomendation

  • Bilbo Wagons

    This video is meant for the %10 who don’t disassemble their own in class

  • Emre Ulusoy

    Yeah. It's 1 A.M

  • SS Squidy

    Me trying to take a test:

    The ADD gang: 0:00

  • OfficialWeeaboo

    lowkey figured all of this out in the middle of a biology lecture, when my pen stopped working and I had to disassemble it.

  • son huynh

    This is what separates us from the monkeys. ……

  • Chris Setyanwar

    Ini ya saya cari 15 tahun yg lalu. Terima kasih banyak.

  • op ostrich

    This has to be a troll video

  • Retro Reegan

    These pens are such an amazing invention!

  • Srujam Dave

    The comments of this video inspired me to disassemble my pen to find out how it worked before i watched the video.

    Edit: I was right

  • Mikey Dooley

    When your teacher tells you to stop clicking your pen out you need to click it again to retract it

  • qwerty uiop

    c l i c k

  • Eꜰꜰi

    So pens aren't powered by magic?

  • Farrel Radithya

    This is exactly what's in my mind when I got bored at school

  • Roshan Mishra

    U r just looking like robert frost

  • Joseph Stalin

    I won't send you to gulag

  • SomeKidWhoWantsABike

    Who else has taken them apart and put them together so many times you already knew this

  • Hariz's channel

    The teachers enemy


    🚹 pan Hand

  • AAFamily Member

    I had the doubt for more than 10 years, now I finaly know

  • Tin foil hats are the new black

    How did i end up here

  • Dima Zubkov


  • Cris Song

    I didn't know I needed this in my life. Wow.. Very Epic

  • Dennis Yang

    I did the exact same thing in a boring English class in middle school. It felt nice to figure how it works XD

  • Dad

    Teachers hate him!

  • Akbaer

    Youtube: Hey, you wanna learn how retractable pen work? Here you go buddy

  • KagemandenDK

    My pen is kinda see-through so I already knew this.

  • Bách Lâm

    ive taught myself how they work

  • Caligula

    You look like a budget mark hamil

  • Vito Scaletta

    no Joke everytime i sit in class i wondered about this topic

  • Masquerade

    Me at 3, ah yes i now know why pen go click click

  • Zaplex PH

    Lol i already figured this out by my self when i am bored st school but with out calculations.

  • MegaMGstudios

    The perfect thing to watch will procrastinating engineering homework

  • Mihai Stan

    Welcome to a new episode of "Why is this in my recommendations"!

  • greenaum

    Genius! Now I get it! So it's not a reciprocating mechanism, nothing needs to go in reverse. It just rotates, round and round, forever. Between the two states, which are implemented twice. It's so simple!

    Thanks, I wondered about this forever! I imagine the patent's long-since expired, so now all pens use a similar mechanism. Or at least most of them, the ones with a separate "release" button are just cheesy and cheap.

  • Random Videos

    Tichuk tichuk wala pen #tichuktichuk

  • Oh no kaushik

    Showed this to vid to my brother, now i can't find my click pens.

  • Gogo

    That's how I study for my uni exams apparently

  • Faisal Alali

    Why am I watching this? I use a mechanical pencil!

  • CyberSERT

    I don't understand what causes the cam body to rotate.

  • Maunster!

    Oh, my God! Like who doesn't know this? Even an elementary school child can figure this out.

  • The gamer

    I can’t wait for a video from the engineer guy explaining how the paper clip works… I have no doubt it will be every bit as fascinating as this one!

  • Belinda Deschamps

    Is there an alternative to the spring force ?


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