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Sturmey Archer 3 speed AW gearhub. How it works.

Sturmey Archer 3 speed AW gearhub. How it works.


In today’s video we will be examining the
three speed gearhub. specifically the Sturmey Archer unit Sturmey Archer three speeds have been in
continuous production since 1902 There have been refinements and
improvements but the basic design remains unchanged Here, we’ll be looking at planetary gear train
basics. We will be examining how the power flow works and finally, we will be looking at an actual
hub gear and showing you how it works. Now let’s take a look at the elements of
a planetary gear train. The sun gear Here we see the sun gear mounted on a Sturmey Archer axle. The planetary gears which are mounted in a
carrier, or cage. Seen here. And the ring gear.
Shown here. Now let’s take a look at how the
power flow works. The power flow requires an input and an output, and a reactionary or fixed In the Sturmey Archer hub, the reactionary gear is always the sun gear. as it is affixed to the axle, and it is the only non moving part in the hub. When the input is the ring gear, and the output is the planetary carrier, and the reactionary is the sun gear, the result is gear reduction or under drive. When the input is the planet carrier, and the output is the ring gear, and the fixed is the sun gear, the result is over drive. Okay, now it’s time to dive into this hub and
show you how it works. The hub we will be exploring is a classic, AW Sturmey Archer 3 speed. This one is actually a new
old stock hub which has never been built into a wheel The build date on this hub is 1956, June of 1956 so it’s fifty seven years old, but it’s a brand new hub. Something a lot of mechanics have trouble with is getting the snap ring off. I did too until I practiced a lot. Now,this is the point where If this hub had been used in a wheel, unscrewing the ball ring with the bare hub not being built into a wheel would be quite a problem because
the torque transmitted to the ball ring tightens the ball ring in the hub shell every time you climb a hill or pedal hard in 2nd or 3rd gear But I’m expecting that because this hub has never been built into a
wheel, it’s probably going to . come out quite easily. Maybe not that easily. There it goes. Now,just a quick word here on dis-assembling these hubs, particularly the older ones. The ball ring thread is what they call a double start
thread. In other words it’s a twin thread, so there’s a thread start on this side, and a thread start on this side. Now I have seen it written that when you’re disassembling these
things, you should watch where the thread releases where it lets go, and mark that spot so
it goes back the same way. I’ve never worried too much about it, and frankly have never had much of a problem. Ok we’ll begin with the bare bones, starting with the bare axle and I will build this thing up, and along the
way I’ll describe the functioning in a way that I hope
you’ll be able to follow along. Here we have the sun gear
which as we noted before is affixed to the axle. That is always the fixed or reactionary gear. Here we have the planetary carrier. which meshes with the sun gear and when it rotates about the sun gear, the planetary gears will rotate. In the first part of the video we looked
at the power flow through a basic planetary gear train. so now we’ll look at how a Sturmey Archer is designed to engage and change the
the power flow route through the hub in order to achieve three output ratios. So first we will take a look at the main parts of the hub . First we have the driver. This is the mean by which the power is transmitted into the hub The sprocket, (or cog), is mounted on the driver And as the pedals are turned, and the chain pulls on this cog and rotates it, it rotates the driver, and transmits the power into the hub. from there, the power is transmitted to the clutch. You see these four prongs on the driver they actually mate with the clutch and transmit the power to the clutch and the driver is in engagement with the clutch in all three gears. When we change gears, what we’re
doing that were changing the position of the clutch within the hub. So,just a a quick run down here.In first
gear, what happens is the clutch is pulled all
the way back to this position. In second gear, it’s in this position, and in third gear, it’s in this position. Now, a little bit about what’s happening in each
of those three positions. In the first two positions, the clutch is actually driving the ring gear. So the power flow goes from the ring
gear, to the planetary. Now remember I said that
when the input is the ring gear, and the output is the planetary and the reactionary is the sun gear, what we have is gear reduction or under drive. Another thing that’s going on inside
here when we’re in first gear, remember I said in first gear the clutch is fully retracted Now the ring gear has drive pawls that transmit power to the hub, by means of the ball ring that screws into the hub. Note the threads on the ball ring, that
screws into the hub hub, And when the ring gear is driving the ball ring, it transmits the power to the hub from the ring gear. These pawls actually extend inside the ring gear, and what happens in first gear, when the clutch is in the fully
retracted position, those pawls are retracted so they do not transmit power to the ball ring. You can see the spring loaded pawls inside, This is how the clutch in the fully
retracted position retracts these pawls so they do not drive the ball ring. What’s happening when we’ve got the
shifter in the first gear position, and the ring gear pawls are retracted, the driver drives the clutch, which drives the ring gear. And the ring gear drives the planet carrier at a reduced speed, and since the pawls on the ring gear are
retracted and not driving the ball ring, it’s the pawls on the planet carrier that engage with the ratchets in the
hub shell. So what we have then is under drive, or
gear reduction for first gear. Now when we shift to second gear, the clutch moves to the middle position, it’s still engaged with the ring gear, but now the pawls have been released so that they will drive the ball ring so as the driver drives the ring gear,
there ring gear drives the ball ring, so we now have a direct
one-to-one ratio so that one revolution of input results in one revolution of output. which is the direct ratio, and that’s our second gear. In the meantime the planet carrier pawls are simply out run by the hub shell,
and you will hear very faint ticking as you’re pedaling as the hub shell is
actually rotating faster then the planet carrier and out running
these pawls so you’ll get a very faint tick tick tick tick
tick as you’re pedalling, and the hub shell out runs these pawls. Now we’ll take a look at what happens in third gear, In third gear, the clutch has been fully advanced to the point where it now engages the pins
on the planetary so the power is actually transmitted directly from the input okay so the input is actually driving the planet carrier. What happens then is, because the ring gear rotates faster than the
planet carrier due to the planetary gears, and now we have driver directly driving the planet carrier which is over driving the ring
gear. The reindeer pawls are engaged to the
ball ring, and they are transmitting an over drive,or
gear increase ratio to the hub shell. so now you have third gear, Again,these pawls are just now going
along for the ride, because the hub shell is rotating at a faster rate than the
planet carrier, it’s simply out running these pawls.l we don’t have to retract them it will just simply ratchet over them. Just so you can see more clearly, I’ve attached a shifter and I will run through this again. In the first gear position, the clutch is fully retracted it is driving the ring gear, with the pawls retracted, the ring gear is driving the planet cage, at a reduced speed. The output is the planet carrier driving the hub
shell by means of the pawls. at a reduced speed for first gear. Now, we shift to the second gear
position, we can see that the clutch has moved along the axle a short distance. It is still driving the ring gear, See these splines, that is how the clutch
engages the ring gear, but now the clutch has moved. in far enough so that the pawls are released., no longer retracted, The driver will drive the ring gear,
and the ring gear drives the hub shell at a one to one direct ratio and that’s our second gear. Now, we shift into third gear, Now the clutch has fully advanced and coupled to the planet carrier by means of these
pins So now,as the driver drives the clutch, the clutches driving the planet
carrier the planet carrier is driving the ring gear, at an increased speed. The ring gear pawls are driving the ball
ring which is driving the hub, so we now have an overdrive gear, and that is our third gear. Now with the unit assembled, we will go through the three gears and
demonstrate what happened with the various internal parts. The shifter is in first gear,which means that the clutch is fully retracted. and the clutch is driving the
ring gear, but the pawls on the ring gear are retracted, so there is no drive action on the ball ring. The power flow is going from the driver to
the ring gear, The ring gear is driving the planet carrier,
at a reduced speed, the planet carrier pawls are driving the hub shell. I’ll show how this works. As we make one full revolution of the driver, we see that the ring gear and the driver have turned one revolution each while the planet carrier has lagged behind. and there is no power being transmitted
to the ball ring. Now we’ll shift to second gear, So the clutch is still engaged to the ring gear, but now, the pawls have been released, so that the pawls on the ring gear are
driving the ball ring, we still have the driver, and the ring gear rotating at the same
rate of speed, and it’s driving the ball ring, so we
have a direct ratio. you see that the plant carrier is still
falling behind because it rotates at a slower rate than the
ring gear. but now the hub shell is turning faster
then the planet carrier, so it simply outruns these pawls. So now when we shift to third gear, the clutch will engage with the planet carrier Watch as we rotate the driver, now the planet carrier and the driver are
rotating at the same speed and the ring gear and the ball ring are gaining in speed, so they’re being over driven by the planet carrier. One revolution input one
revolution on the planet carrier, the ring gear and the ball ring are gaining in speed so we are over driving the hub, and that is third gear. There is one flaw in this particular design. One thing that this hub is
notorious for is what they call the in-between gear or the false neutral. That happens between second and third gear if the shifter is not set exactly right. what can happen between the point where the clutch leaves engagement with the ring gear, and before it actually engages on the
planetary carrier pins there’s a very narrow window in there where there is no drive taking place. So what can and sometimes does happen is you can be pedaling along and shift a gear, and it goes to neutral. There is no engagement. The new production Sturmey Archer 3 speed has addressed this, there’s been a design change mostly around the driver of the
new redesigned unit. The basics are the same. The ratios are the same, the function is the same, but the driver system has been
redesigned. I will be exploring this in a future video and demonstrating that change.

86 comments on “Sturmey Archer 3 speed AW gearhub. How it works.

  1. Many thanks, this is very useful, and nice to have an in-depth explanation, instead of one reduced to soundbites. A suggestion (not a cristicism): may I suggest that you try using more even/diffuse lighting, and perhaps a less cluttered background, so that everything is more easily visible?

  2. Absolutely brilliant- really good explanation of what is going on- thanks for taking the time to make this film!
    best wishes
    Rich
    ( windmill hill bike doctor)

  3. Excellent video, thanks for this. I've taken these hubs apart before and I had a rough idea how they worked, but this explained a lot more.

  4. Bravo -great job! I'm very impressed at how you manage to remember the names of the components as the demonstration unfolds without any hums or hurs 🙂

  5. Outstanding. I've been riding SA hubs for 50 years or more – actually more – and had a rough idea of their functioning, but this really explains it. Good work.

  6. Good work on explaining the working of this hub. I am thinking about using one of these on my bike. Thumbs up!

  7. Excellent video, many thanks for the careful explanation, I think I finally understand it but I still wouldn't like to try to put one back together.

  8. Thanks for the clear explanation,Dan!
    I came here because my Sachs 3speed hub is permamently stuck in 1st.
    I took it apart thinking I could grease it up & reassemble, but the parts got scrambled 🙁
    If you ever lay hands on a Sachs, could you do a dis,-& re-assembly?
    Even if you don't: Fantastic work work you're doing!

  9. I've explored 7 speed Sachs hubs, but never a 3 speed. My main concern is the unavailability of replacement parts for them,unlike Sturmey Archer which has parts support for hubs going back many years.

  10. Is it remotely possible to fit a Sturmey gearbox into a Sachs hub? are they the same diameter (43 mm), to your knowledge?

  11. You are brilliant ! I loved my old 3 Speed back in the early 70s, and now many years later I discover how the hub gearing works ! Are you a mechanics teacher, or a professional bicycle mechanic ?

  12. Thank you for the kind comments. Semi retired trucker and semi professional bike mechanic. Not a mechanics teacher.

  13. GREAT job, Dan. I was born in 1958 and have one foot in the mechanical age and the other in the electronic age. It seems that an appreciation for mechanics has gotten drowned out by computers, video, circuits, and pixels. Thanks for an eloquent, clear lesson on the genius of mechanical design, and what happens when I click that little lever that enables me to get up the hill just a bit easier!

  14. Have just bought a couple of"dahon"older folding bikes,great to have had an insight into how the"Sturmy Archer" gears work,they do seem lots more complicated than standard cogs etc with the"lever style operation"but maybe need less maintenance thanks for the informative+detailed explanations,lots of the time the detail is a little vague,yours is very explicate,cheers from Bonnie Scotland ,I want to use them in conjunction with my old vw camper(not running currently)fingers crossed next summer

  15. So good I had to applaud! Now I do not have to take it apart to see how it works. The part with the electrical tape at the end was genius. Thanks for the effort.

  16. This is a great video to watch. I like how you take your time showing how everything works instead of going so fast I have to replay over and over to understand what happened. I do have one question for you. I also have an older sturmey archer from '61 that needs some cleaning. My question is how do I lubricate this correctly? I keep watching videos on how they use grease on everything. With your video everything is oiled and looks as if you don't use grease. Any videos or anything that can help me thanks.

  17. Thank you for the comment Trent. The outer bearings should be greased same as any bike axle bearings, but for the internals, a light oil such as ATF or light viscosity base oil with no additives is fine.

  18. Great! I have been searching a video about internal gear working. because I want to maintain a my sram T3 by myself. This video is very helpful to me and my brompton friends. I will link this video on my brompton online club S.Korea. Thank you very much.

  19. Thanks for all the great videos Dan!  I'm fascinated by the intelligence that goes into the internally geared hubs. Your videos do a great job explaining their workings and maintenance. I've owned many S.A. 3 speed hubs (AWs) and one 5 speed.
    While on the subject of gears, I think that the differential found on cars and trucks etc. is simply an ingenious invention. Necessity may be the mother of invention but brains make them happen!  Dave D.

  20. Thank you very much for this very informative video. I learned quite a lot about the function of the gear and you explained it really good 🙂
    Cheers

  21. Thanks for actually taking the time to make this video so that a bunch of us can learn this important aspect of bicycle mechanics.  What a great explanation!

  22. Do you think it's strong enough to be driven by an engine? I have made a chainsaw bike, and I want a gear shifter, gear hub would be the best solution, but is it strong enough? The normal mountain bike casette system works well now, with that 2 little hammers. I see them here too, but they are bigger. Is that means, they are stronger than the mountain bike ones?

  23. Great video!
    After watching your "Sturmey Archer NIG" video, I want to replace the (Sachs Torpedo) 3-speed coaster brake hub on my classic steel city-bike.

    I have read Sheldon Brown's IGH article and the part where he says: "A coaster brake in an internal-gear hub is, all in all, a poor idea because of the wear particles it generates, and because you can't use oil lubrication."

    So my impression is that an IGH with drum brake has technical advantages compared to a coaster brake. I would like to hear your opinion.

    Do I need extra mounts on the chain stays for an IGH drum brake version e.g. XL-RD3 ?

  24. I just love your channel, it's so clearly explained! Is the picture of your channel taken on the Brouwersgracht in Amsterdam?

  25. Thank you so much! Even though I'm not perfect in English I've understood everything so clearly! This was very interesting lesson.

  26. Thank you so much! Even though I'm not perfect in English I've understood everything so clearly! This was very interesting lesson.

  27. When I try to change from Speed 3 to Speed 2, the coupling becomes neutral.
    Can I eliminate or minimize this by proper adjustment of the shifter? If so, please let me know how to adjust the shifter.

  28. That was a pretty understandable demonstration and explanation of the workings of a 3 speed. I find it amazing that the palls can withstand the torque of going up a hill without become burred or otherwise damaged and also the really tiny springs that allow them to ratchet.

  29. Thanks for all the work you put into this to school us sheep. I really appreciate it ! Looked over a bunch of your vids, looks like you have an interesting and rich life ! 

  30. Do I have anything to back this up? No. But I bet my ass SA are few times more durable and serviceable, seeing what kind of monopoly Shimano I now.

  31. hi All i know is that these hubs are a briĺliant bit of kit!
    Apart from that im trying to get a date for an SA hub with no date but it does say AW9 ????

  32. I always wondered how these things worked. Thank you for a good video explaining them. I subscribed and watched many of your other gearbox "tear downs" too. Good stuff!

  33. excellent info Dan – the 1st & the 3rd gear of my Raleigh Sturmey archer gearbox is not shifting well…i dont know what has gone wrong.

  34. Wow, THANKS!  You just told me why the pedals spin freely in 3rd gear! A shift cable adjustment should do the trick… I was afraid it was broken.  I just acquired 2 bikes, a '64 Schwinn and a '73 Raleigh, both with SA hubs…the Schwinn has the problem hub.

  35. Hi Dan!
    Great video, thanks!
    I have a question, my shifting cable has been breaking off and I just can't handle it anymore, riding on the 3rd gear is getting tough. Is there anyway I can lock the clutch in position so the 1st or 2nd gear is always driven?

  36. Thank you very much for the video! Maybe you can help me with something. I'd like a 3-speed with a coaster brake for my father-in-law with rheumatoid arthritis. But my research indicates they aren't very durable, not like the AWs are. Is there a good SA with the coaster brake I'm missing?

  37. I just bought a Huffy single speed cruiser with a steel frame (a cheap bike, I know), and I want to install a Sturmey Archer 3 speed hub with a coaster brake. The rear hub spacing on the chain stay drop outs is 110 mm. I have researched and found only two Sturmey Archer 3 speed models with coaster brake that would fit: AWC (II) and S-Rc3(l). Both have 116mm outside locknut spacing. Which one do you think would be the best one for me? I think I can spread the rear drop outs wide enough to accept the 116mm hub.

  38. Great Job on explaining the internals of a planetary system. Wheres the best place to Purchase 3 or 5 speed for my Bike build. Or would you purchase a different brand ?

  39. Thanks for showing all the internals and the function of this hub you answered my questions plus you answered what the hell the new drive gear with the 2 rows of pauls was about I found it on my gt intruder bmx rear hub (standard fixed, No archer on it)

  40. When my five speed derailleur ( Motobecane ) was stolen from the school bike shed back in about 1977 I had to ride my sister's Raleigh 20 ( 20" wheels ) Shopper to school for a year with it's three speed Sturmey Archer gears. Oh the abuse I took from the other kids. Still it was funny when I left them for dead and they saw the white shopping bag on the back disappearing into the distance. The SA 3-speed was for ladies'bikes and for the occasional old codger on a Raleigh Hercules. I didn't appreciate its reliability as a kid.

  41. What a nice and durable mecanism Sturmey Archer is (better than all Shimano stuff) and good explanation in the video; but the sound is too low. Anyhow, thank you.

  42. Hello Mr. Dan would like to get a hold of you. I have a few questions -like to add a motor to bicycle gears wondering how much torque can they take?hope to hear from you thank you

  43. The pore audio on this video, I am useing an extension speaker as an earphone. This is working for me.
    I'm thinking that a smart phone with an extension cord to the computer would work, Could some one confirm this, Or give a reason.
    Penny Farthing Bycicle Mechcanic.

  44. Great Video Sir , extremely easy to understand !! Will try overhauling my grandfather's Raleigh , with the same (in video) SA-3speedhub. Great explanation !!

  45. How do I lube this hub without taking the chainguard off and taking the plate off? Isn't there some kind of "indicator" hole I'm hearing about?

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