
Epicyclic Gearing - llambda
http://bl.ocks.org/1353700
======
joe_bleau
Another good one is the hypoid gearset (<http://en.wikipedia.org/wiki/Hypoid>)
, as used in automotive rear ends. For some reason I've always found them
pretty.

Cone drive sets and harmonic gearing
(<http://en.wikipedia.org/wiki/Harmonic_drive>) are neat, too. And then
there's the Torsen (<http://www.youtube.com/watch?v=Z9iPqIQ_8iM>), which I
still don't really understand.

From the service manuals I've seen, I think some of the smaller 4 cylinder
cars, especially from Japan, use a mainshaft/countershaft arrangement (like a
traditional manual transmission) in their automatics, rather than planetary
gearing.

~~~
HeyLaughingBoy
Because the machining is _gorgeous_

I used to have the hypoid pinion I removed from my Toyota pickup truck rear
end (when I changed the gear ratio to compensate for larger tires) as a
paperweight on my desk. The flowing curves and polished steel gave it a really
Art-Deco look.

It was free, beautiful and weighing close to 10 lbs, very functional. Can't
beat that :-)

~~~
joe_bleau
Speaking of gorgeous, if you're ever in a machine shop and get a chance to
look inside the headstock of a top end 1940-1970s vintage engine lathe, do it.
The quality and precision makes automotive stuff look like hammered pot metal.

~~~
HeyLaughingBoy
I hang out on a couple of online machinist fora and I agree. Even the outsides
of something like, e.g., a Monarch 10EE are beautiful. Sculpted in a way that
just doesn't seem to happen anymore.

Two of my favorite machine porn photos are from WW2 - a woman at a beautiful
Warner & Swasey turret lathe: <http://www.shorpy.com/node/1809> There's
another one on that site of a woman using a Heald Borematic that I can't find
right now, but it's even more amazing. I need to find it so I can order a
large print.

Yeah, I love machine tools :-)

~~~
joe_bleau
The EE is just about the ultimate, isn't it? I'm also a fan of the smooth
flowing industrial design of the old Cincinnati horizontal mills.

------
samlittlewood
This was how the Model T Ford transmission worked - the foot pedal fixed
various parts to get low, high and reverse.

Edit: <http://www.modeltcentral.com/transmission_animation.html>

------
bprater
Quickly clicking thru the options on this webpage will give you an idea on how
automatic transmissions work in automobiles -- using the planetary gearset.

The core mechanic is the locking of different combinations of the gears. This
is a completely different mechanic than in the standard 'stick shift' manual
transmission, which uses traditional toothed gears meshing together.

~~~
pkulak
I think you're thinking of an electronic CVT, like the Prius uses.

~~~
abthomson
Both "normal" automatic transmissions and the Prius use epicyclic gears. The
main difference between the two would be that an automatic transmission in
normal operation has one power input (the engine) and one output. As bprater
alluded to, any variation in gearing is achieved through fixing different
parts of the transmission.

The Prius has two electric motors and a gas engine. It's not a CVT in the
traditional sense though, this simulator does a good job of demonstrating how
it works(implemented in Flash, not D3...) <http://eahart.com/prius/psd/>

~~~
robgolding
That simulation is absolutely fascinating. I knew hybrid cars were packed with
loads of advanced _electronic_ tech, but the use of epicyclic gears as the PSD
is pretty cool.

~~~
lloeki
Toyota's HSD system uses such a scheme, but mechanically, Honda's IMA replaces
the flywheel with an electric generator/motor, the remainder of the drivetrain
being your typical car (they use either a CVT or a manual stick, depending on
models and regions). The key then is entirely in the logic driving the
electric motor and the VTEC system.

[0]
[http://www.blogcdn.com/www.autoblog.com/media/2010/06/2011cr...](http://www.blogcdn.com/www.autoblog.com/media/2010/06/2011cr-z008technical-
copy.jpg)

------
raymondh
Beautiful website. Fascinating display. Nice source code.

~~~
mikepurvis
Agreed, very nice. I did some demos like this a few years ago, and it was
definitely not as clean. Modern JS libs are marvelous things.

(eg: <http://sandbox.mikepurvis.com/design/engine.svg>)

------
jebblue
Interesting but it uses 80% CPU time on my system, here is a Java applet
showing the same thing - it takes a long time to load but uses less than 10%:

<http://www.zfm.ethz.ch/meca/applets/planeten/PG.html>

------
jakeonthemove
That's also how chain hoists work - I'm still amazed at how much you can lift
using one!

I actually thought the article will be about Biopace bike chain rings: bikers
are using them as an advantage in races (and it really makes sense!).

~~~
Terretta
Supposedly, Biopace was shown to be counterproductive, while the newer Rotor
Q-Rings are correctly designed.

The new hotness: <http://www.rotorbikeusa.com/science.html>

