December 29, 2011 • 20 mins
Transmissions regulate the power coming from an automobile's engine to its wheels. There are several types of transmission systems, and continuously variable transmissions are Scott and Ben's favorite. Find out why in this podcast from HowStuffWorks.com.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Go behind the wheel, under the hood and beyond with
car stuff from how stuff Works dot com. Hi, everybody,
Welcome to the podcast. I'm Scott Benjamin, the auto editor
here and how Stuff Works, and I'm here as always
with Ben. How are you doing today? Ben? I'm doing
super well, Scott? How are you doing? Also? Super well?
(00:23):
Super well? That's a good one, you know. I just
pulled it out, but I don't know. I think it works.
How do you feel about it? Great intro, by the way,
I appreciate it. I'm trying them out and I think
it's going smooth. So I'm not gonna out of the
park anyways. I'm not smooth of the transitions like you are.
So I'm just gonna say we're gonna talk about some
transmissions today. Transmissions. Okay, transmissions, that's perfect. Let's get into
(00:45):
a because we've done some speculive podcasts, but let's get
into some nuts and bolts. Um first, I guess uh
for everyone out there who happens not to know what
is the transmission and what does it? Do? You know what? Sorry? Ben,
Here's what I'm gonna do. I'm gonna back up for
just one second. Okay, all right, excellent question. I'm gonna
(01:06):
back up and say that this is a listener request.
I I neglected that. I just peeled off a post
it note and I saw my note here that say
that it is a listener request, and I feel we
need to tell them that. Um it was actually from
two listeners and these are going way back. UM so
as sometimes happens. Um. Someone named Zach and also someone
named Rohan wrote in said that they would like to
(01:28):
hear um some information about c vts in particular continuously
variable trans to see you know what I'm going I'm
going forward their continuously variable transmissions and um, actually they
had questions about a lot of different transmissions. We're gonna
focus on CVTs in particular in this episode. So so
Zach and Rohan, this one's for you and also for
everybody else. Thanks for writing in, guys. We love listener mail.
(01:49):
Oh by the way, Rohan's from India, India, Mumbai, India.
That is awesome. Yeah, pretty cool. We have listeners all
the way out in India, yes, and we think all
of them are fantastic. Course, wherever you're from, I guess
everybody listening to this is from the internet. Just pretty
amazing to me to understand that what we do here,
(02:11):
you know, what we're recording is truly going around the world.
Everybody's really paying attention. Well, everybody loves cars. Okay, that's
interesting enough enough, patting ourselves on the back. That's that's
pretty pretty cool though, I thought. So anyways, we can
get right into it and we'll talk about c vt
S if you like. I'd love to, yes, break it
down for me. Well, you had a question for me, right,
I did. I did just just to establish some parameters. Uh,
(02:34):
what are transmissions and what do they do in a car?
Trans simple enough? Transmission. UM, every vehicle has one, really,
almost every vehicle has one. UM. All they do really
is just they change the speed the ratio coming from
the engine speed to the wheels. UM. Probably just goofed
that up, but close enough. What what it does is
(02:54):
it makes the power coming from the engine usable at
the wheels because if you didn't have any gearing in between,
it's it's a gearbox really, and if you didn't have
any gearing in between, you would have basically one gear
between the engine and and the wheels, and it would
be whatever speed the engine is going. So does this
modify torque. H it does it does? You're right, So
(03:15):
it's it's a twisting force that is then you know, converted, Well,
it remains twisting force all the way to the wheels actually,
but um it it is modified into usable ratios that
can be uh um helpful for accelerating climbing hills, going downhills,
um just top speed, um, any any driving situation really
(03:38):
because you need all these different ratios in order to
do that effectively. Now you know where I'm going with this.
That's a basic transmission. It is a basic transmission. Yeah.
What makes a CVT different CVT and it's really popular
right now. We'll talk about that in a minute too.
But a CVT is a continuously variable transmission. And what's
(04:01):
what's unique about a CVT is that it doesn't have
any stepped gears, any any specific um hard set of
gears where this is always going to be the ratio
when you're in this gear. Continuously variable transmission, just to
the name suggests, it's continuously variable, has an infinite number
of ratios and we'll describe how that's possible in a minute.
But an infinite number of ratios that are accessible at
(04:25):
any point really I mean it's able to adjust to
your driving pattern or Um, I guess I should say
more to the to what you're asking it to do
to driving conditions, driving conditions. That's better. That's a better
way to say that. How exactly does that work? That
seems very difficult. Well, there are three different types of
the three different types of CVTs, and we're going to
(04:47):
focus on the most common type, which is the Pulley type. UM.
The Pulley type is the kind that you'll find in
automobiles right now. UM. There are several other other different types. UM.
There is a I'm gonna mess up the name of this,
but I have a hard time saying this word, but
Treroy deal which is t O R O I D
(05:09):
A L t roidal CBT, which has no pulleys. It
uses disks and uh and power rollers and it's really
I mean, you're gonna have to look these up just
to see what they what they look like. We've got
an article about c vts on our site, so check
it out. UM, you can find a good graphic of
these there. And there's also a hydrostatic uh CBT, which
uses variable displaces but pumps um or hydrostatic motors, So
(05:34):
it uses UM the it converts the rotation the engine
into UM well flow power I guess, not flow power,
but um but fluid flow. I don't know a better
way to say that. But it uses pumps and fluid
in order to to make the whole system work. And again,
(05:54):
check out check out the site. You know what, you'll
understand this, Like, there's no way I can describe it
right here. What's going on? You do have to see it? Yeah, Um, anyways,
hydrostatic motors, it's it's a little more complex than, of course,
but the ones we're talking about or the Pulley Thanks
for getting me back the Pulley system. Now, let's see
if I can describe this right there. Two. It's real simple.
(06:16):
It doesn't have a whole set of gears like a
like a normal automatic transmission would. And we're not even
talking about manual here because really a CBT is like
an automatic. Uh. You don't shift a CBT other than
you know, if there's an option to do that. You know,
some of them have these sports shifting sections. We'll talk
about that a little later too. Good. Um, basically, it's
(06:37):
an automatic transmission and they're really it's so simple inside,
there's a there's a drive pulley and a driven pulley. Now,
the drive pully is connected to the crankshaft which comes
out of the engine, and the driven pully is the
one that transfers that energy to the drive shaft. Okay, okay,
So crankshaft is the the drive pully. The one that
connects to the drive shaft is the driven pully and
(07:00):
ends as the output between those two. And this is
where it's a little complex there. Um between those two
for automotive purposes, there's a metal belt. It's a it's
a metal belt, which is kind of unique. And now
the belt is is fashioned of several bands that are
run together, maybe a dozen bands, and those are and
that's held together. All those bands are held together with
(07:21):
these um looks like metal keys almost, and there's thousands.
I'm gonna say a thousand, but it's probably more than that,
I'm guessing, because there are that many of them in
this belt. It's very heavy, heavy belt, real heavy duty UM.
And that's what runs between the two pulleys. And we'll
describe the pollis in a second too, But I want
to tell you that a lot of CVTs that use
(07:42):
this pulley system. Um, they don't have to be in cars,
by the way, UM, CVT has been around for a while.
They've been in power tools, drill presses, tractors, snowmobiles, motorcycles,
but they've all used rubber belts in between the pulleys.
And so now the difference is CVTs and cars in
order to handle of the torque on the tower that
you know, and just for durability to use these steel
(08:04):
steel belts. Oh wait, wait, wait one second, no, I
I have to ask you just step back for a second. Um,
how recent or old is this technology? He said, it's
been around for a while, which kind of surprised me.
It's been around a long time. You want to take
a while, I guess do you know? What? Do you
know the answer? Are you just messing with me? Because
(08:26):
if you know, come right out with it, because it's
it's unbelievable when you hear it. Okay, against if I'm wrong.
Leonardo da Vinci really really really blows my mind. Fourteen
ninety is when Leonardo da Vinci, who we've talked about
many times on the program, how he's just just unbelievably advanced. Um,
(08:47):
you know, early thinker. Um, he sketched a stepless continuously
variable transmission in fourteen ninety. If you can believe that,
I mean, I'm trying my best to believe it. I mean,
I have no idea what it looks like. I and
seen this the sketch, um, or how it compares to
what we actually have now. So it had to be
made of wood or something. I don't know. I don't know, stone,
(09:09):
I don't know. I don't really I don't know. Probably
would probably would, and but I don't know. I mean,
I'm guessing vines or something in between the pullies. I
don't Maybe it wasn't a Pulley system. Maybe there's some
other type of system I don't know, four ninety that
would make this uh hundreds and hundreds of years old,
five hundred and twenty years old at this point, something
like that, I mean ballpark. But I guess when you
(09:33):
get down to it, though, it really wasn't built or
or in production, you know, it's not really serving the
purpose that it should. Yeah, that's right. It was conceived
at that point. Um. And you know what, I'm gonna
go earlier than this, I got it. I got to
note here that says nineteen fifty eight, there was a
car that used the CVT in the Netherlands. But um,
(09:53):
I'm gonna go back even further. Then. There's a company
called Zenith Motorcycles and they originated in nineteen o four,
and Zenith Motorcycles had a device that they called a
graduate gear. It's like almost like gradual without the L
at the end. Graduate gear, and it used a variable
(10:13):
pulley system that would vary the length of the drive
belt by moving the rear wheel forward and backward in
its slot. And this apparently gave Zenith Motorcycles a such
a an advantage at the time in this in this
hill climb competition that they were in our hill climb
competitions gave the writers such an advantage that they were
(10:34):
banned from competition. It was that much better than everything
else that was out there. Weird standard standard shift, that's weird.
It's like you heard about the I think they're German.
There's a swimsuit company whose swimsuits have been banned from
professional competitions because the improvement is that noticeable? Is that something?
(10:55):
I mean? I mean, I I say, you know, great,
you know, move on with technology. But um, they held
them back, I guess, but you know, it doesn't didn't
hold them back from producing the motorcycle. They still produced
the motorcycle until I believe it was so after you know,
after World War Two, they were still producing motorcycles just
for a short time and then they went out of business.
But um, early on they were banned from competition because
(11:18):
they had this advantage. And this this technology, as you
said earlier, is is pretty widespread still, right. It was
in power tools, you said, I'll tell you it's in
power tools, it's in snowmobile. A lot of people know
there's some snowmobiles. Um, it's from tractors, drill presses, um, again, motorcycles.
I think there's probably other applications of this, we're just
(11:39):
not seeing them here. Um. But it's it's really kind
of cool. I mean, I'll just get a super basic
description of what it is. Is two pulleys that have
um cone shapes UM to the inside edge of those
those pulleys, and there, of course position right next to
each other. The belt runs between them. The belt always
remains at the same tension, it never gets slack, it
(12:01):
never gets tighter, and when when speeds go up, you know,
one of the sets of pulleys expands and and the
belt rides down further in that in that groove, and
it goes higher up on the groove and the other
pullets at a police So it's this kind of seesaw
back and forth motion. So at higher speeds, the pulley,
you know, on one set of pollis, it will be
(12:21):
you know, riding deeper into that groove, that V shaped
groove that the pulley creates. And on the other set
of pollis then it will always be at the top end.
And I don't mean always, but I mean if it's
low on one end, it's high on the other, and
then it it balances itself out and it just goes
back and forth between the two. So there's a there's
something here that that kind of presents a question to us,
(12:44):
or heavily implies this question. If this technology has been
around for so long, um, is it the norm? It
is becoming the norm? Um. And that is evident in
that there are some manufacturers that al will offer only
manual transmission or a CVT. You can't get an automatic
(13:04):
transmission in some models, not that the manufacturer doesn't offer
an automatic transmission, but you know, that's the that's your option.
Either get a manual transmission, you know, six speed standard shift,
or you get a CBT and go ahead. Well, I
was just gonna I was just gonna say, uh, with
the reference to the manufacturer in the Netherlands, is this
(13:27):
technology more common in one car market than the other,
like Japan or Europe or anything. Actually not, um as
far as I can tell right now. And I couldn't
say for certain whether there are more cars on the
road with CVT in in Europe or in Japan or wherever. UM.
I can tell you though that since well, I mean,
I guess I can just start right here at the beginning.
(13:48):
There was one vehicle sold here in United States that
had a CVT, and that was just the one that
was in nineteen eighty nine Subaru just e g L
and it just never took off, never never really gain
any popular And I don't know if that had anything
to do with the UH CVT or not. I couldn't say.
It's just could have been any of the number of
factors exactly exactly. Now you've got companies like Nissan, and
(14:12):
there's a player Jetco who makes their CVT. That's there's
transmission supplayer. They to date have sold over one million
CVT equipped vehicles. UM, so you can see that. You know,
they're everywhere. I mean they're populating, populating all the continents.
I guess, Um, it's not just Nissan, it's GM, it's Audi,
(14:35):
it's Honda, Nissan, Chrysler. They're all getting into the CVT game.
UM relatively recently, I mean in the last few years.
But um, Nissan has really been kind of leading the
way with this one. I wouldn't say that they were first,
of course they weren't, but um, right now they may
be the ones doing it the best. I've got to
ask one one other thing here that we we actually
(14:58):
we did not we did not talk about earlier. But
what what do you think makes this technology, uh, advantageous
or disadvantageous in comparison to an automatic transmission? Well, um,
it's it's got a smoothness to it that automatics do
not have. Because even in an automatic, you can you
feel that shift. Yeah you still have stepped gears. Yeah
(15:20):
you're right, you still feel that And now I do
a lot of people that's not good. They don't want
to feel that smoothness because it feels like something's wrong.
If you've you've driven a car before where you know
there's slipping clutch or the gears are going through there something,
you know that slipping feeling, and that's what you get
in a CBT equipped vehicle when you when you step
on the gas at a light, you'll hear the engine
(15:42):
kind of spool up. You know, the revs will go up,
but the car doesn't really go anywhere. It's so it's
slowly sorry, it's it doesn't it doesn't match the way
that it feels like it should or that we're accustomed
to it, uh happening, So what if what's happening though,
is it's searching for the right ratio in order to
take off, and then it maintains that proper ratio throughout
the whole drive cycle. So it feels really odd and
(16:05):
it's extremely smooth, and to some people that just doesn't
feel right. Other people kind of blissfully unaware, even don't
even know that, you know, they have a CVT and
everything is just fine. They don't really care. What do
you see as the future of CVT. You know what,
I've been thinking about this one because I knew you're
gonna ask me this I think and and honestly, you know,
(16:28):
I mean I'm surprised that the way I just can't
believe the technology already that we have. I mean, it's
pretty amazing, it really is. When you when you look
at some of the details of these transmissions and what
they can do and what they're capable of. They save fuel,
they're extremely smooth, they're very um, they're very simple. Really inside,
there's not it's not nearly as complex as a standard
(16:48):
automatic transmission. What I would say, um, future developments, I
mean I can only guess, but I mean I'm saying,
like further simplification. Maybe it just refinement of what's already there.
If it can be further simplified, I don't even know
if it can at this point, but never say never.
And um, i'd also say further weight reduction because weight
reduction is um it's so key right now, It's very key.
(17:11):
I mean, it's uh, it's critical when you're talking about
downsizing engine sizes and vehicle weights and you know this
is all part of it. The transmission has to be
reduced as well. I mean, every little bit counts, So
I would say further weight reduction is important. And I
guess use of new materials. I mean, I I can
only think that you know, that would help in weight
reduction and not so much simplification, but new materials might
(17:35):
be one way to go. It's kind of you know,
in these in these episodes, I've noticed we're reaching towards
this is uh, some of the same recommendations again it again,
and those are better materials, higher efficiency, less weight. Yeah,
and you know what, now that we think about maybe
(17:56):
something in the future we could we could go we
could go a little bit deeper into that. Sure all
three are tied together. Um, and the new materials tend
to be lighter the of course that's weight savings and
weight savings increases efficiency. Hey, Scott, are we are we
wrap it up on transmiss you feel like it? You
know what I do. I'm sure there's plenty of questions
(18:18):
out there, so you have had it asked me and
ask me what you like. And also, you know, let's
just say go to the site our our website, how
stuff works dot com and check out the article how
cbt s work and that will clear up a lot
of questions because if you do have questions, their charts, graphs, advantages, disadvantages,
um a lot of a lot of explanation that you know,
we just couldn't go into here. And I also I
(18:41):
urge you to go online and there's a lot of
animations of CVTs in action and that will clear up
a lot of questions you have as well. I mean,
I've watched many of these over I don't know how
many years, I guess, and m to me that just
just being able to see it in action, that really
it makes perfect sense to you once you watch it. Okay, right,
you heard it here first hopefully about how CVTs work.
(19:04):
And as Scott has pointed out, you should definitely check
out the information on the website. While you're there, you
should probably check out his blog, Scott, I don't want
to embarrass you. That's sorry about the Ferrari crash. It's
pretty awesome. Yeah, yeah, there's some there's some disturbing news
about a classic Ferrari, so you want to check out
and there there uh, there's always something on that blog
(19:26):
that is just utterly fascinating. And if you have any questions, comments,
or suggestions for a future episode, please do send us
an email at high Speed Stuff at how stuff works
dot com. Be sure to check out our new video podcast,
Stuff from the Future. Join how Stuff Work staff as
we explore the most promising and perplexing possibilities of tomorrow.
(19:49):
The house Stuff Works iPhone app has arrived. Down with
it today on iTunes,
Go behind the wheel, under the hood and beyond with
car stuff from how stuff Works dot com. Hi, everybody,
Welcome to the podcast. I'm Scott Benjamin, the auto editor
here and how Stuff Works, and I'm here as always
with Ben. How are you doing today? Ben? I'm doing
super well, Scott? How are you doing? Also? Super well?
(00:23):
Super well? That's a good one, you know. I just
pulled it out, but I don't know. I think it works.
How do you feel about it? Great intro, by the way,
I appreciate it. I'm trying them out and I think
it's going smooth. So I'm not gonna out of the
park anyways. I'm not smooth of the transitions like you are.
So I'm just gonna say we're gonna talk about some
transmissions today. Transmissions. Okay, transmissions, that's perfect. Let's get into
(00:45):
a because we've done some speculive podcasts, but let's get
into some nuts and bolts. Um first, I guess uh
for everyone out there who happens not to know what
is the transmission and what does it? Do? You know what? Sorry? Ben,
Here's what I'm gonna do. I'm gonna back up for
just one second. Okay, all right, excellent question. I'm gonna
(01:06):
back up and say that this is a listener request.
I I neglected that. I just peeled off a post
it note and I saw my note here that say
that it is a listener request, and I feel we
need to tell them that. Um it was actually from
two listeners and these are going way back. UM so
as sometimes happens. Um. Someone named Zach and also someone
named Rohan wrote in said that they would like to
(01:28):
hear um some information about c vts in particular continuously
variable trans to see you know what I'm going I'm
going forward their continuously variable transmissions and um, actually they
had questions about a lot of different transmissions. We're gonna
focus on CVTs in particular in this episode. So so
Zach and Rohan, this one's for you and also for
everybody else. Thanks for writing in, guys. We love listener mail.
(01:49):
Oh by the way, Rohan's from India, India, Mumbai, India.
That is awesome. Yeah, pretty cool. We have listeners all
the way out in India, yes, and we think all
of them are fantastic. Course, wherever you're from, I guess
everybody listening to this is from the internet. Just pretty
amazing to me to understand that what we do here,
(02:11):
you know, what we're recording is truly going around the world.
Everybody's really paying attention. Well, everybody loves cars. Okay, that's
interesting enough enough, patting ourselves on the back. That's that's
pretty pretty cool though, I thought. So anyways, we can
get right into it and we'll talk about c vt
S if you like. I'd love to, yes, break it
down for me. Well, you had a question for me, right,
I did. I did just just to establish some parameters. Uh,
(02:34):
what are transmissions and what do they do in a car?
Trans simple enough? Transmission. UM, every vehicle has one, really,
almost every vehicle has one. UM. All they do really
is just they change the speed the ratio coming from
the engine speed to the wheels. UM. Probably just goofed
that up, but close enough. What what it does is
(02:54):
it makes the power coming from the engine usable at
the wheels because if you didn't have any gearing in between,
it's it's a gearbox really, and if you didn't have
any gearing in between, you would have basically one gear
between the engine and and the wheels, and it would
be whatever speed the engine is going. So does this
modify torque. H it does it does? You're right, So
(03:15):
it's it's a twisting force that is then you know, converted, Well,
it remains twisting force all the way to the wheels actually,
but um it it is modified into usable ratios that
can be uh um helpful for accelerating climbing hills, going downhills,
um just top speed, um, any any driving situation really
(03:38):
because you need all these different ratios in order to
do that effectively. Now you know where I'm going with this.
That's a basic transmission. It is a basic transmission. Yeah.
What makes a CVT different CVT and it's really popular
right now. We'll talk about that in a minute too.
But a CVT is a continuously variable transmission. And what's
(04:01):
what's unique about a CVT is that it doesn't have
any stepped gears, any any specific um hard set of
gears where this is always going to be the ratio
when you're in this gear. Continuously variable transmission, just to
the name suggests, it's continuously variable, has an infinite number
of ratios and we'll describe how that's possible in a minute.
But an infinite number of ratios that are accessible at
(04:25):
any point really I mean it's able to adjust to
your driving pattern or Um, I guess I should say
more to the to what you're asking it to do
to driving conditions, driving conditions. That's better. That's a better
way to say that. How exactly does that work? That
seems very difficult. Well, there are three different types of
the three different types of CVTs, and we're going to
(04:47):
focus on the most common type, which is the Pulley type. UM.
The Pulley type is the kind that you'll find in
automobiles right now. UM. There are several other other different types. UM.
There is a I'm gonna mess up the name of this,
but I have a hard time saying this word, but
Treroy deal which is t O R O I D
(05:09):
A L t roidal CBT, which has no pulleys. It
uses disks and uh and power rollers and it's really
I mean, you're gonna have to look these up just
to see what they what they look like. We've got
an article about c vts on our site, so check
it out. UM, you can find a good graphic of
these there. And there's also a hydrostatic uh CBT, which
uses variable displaces but pumps um or hydrostatic motors, So
(05:34):
it uses UM the it converts the rotation the engine
into UM well flow power I guess, not flow power,
but um but fluid flow. I don't know a better
way to say that. But it uses pumps and fluid
in order to to make the whole system work. And again,
(05:54):
check out check out the site. You know what, you'll
understand this, Like, there's no way I can describe it
right here. What's going on? You do have to see it? Yeah, Um, anyways,
hydrostatic motors, it's it's a little more complex than, of course,
but the ones we're talking about or the Pulley Thanks
for getting me back the Pulley system. Now, let's see
if I can describe this right there. Two. It's real simple.
(06:16):
It doesn't have a whole set of gears like a
like a normal automatic transmission would. And we're not even
talking about manual here because really a CBT is like
an automatic. Uh. You don't shift a CBT other than
you know, if there's an option to do that. You know,
some of them have these sports shifting sections. We'll talk
about that a little later too. Good. Um, basically, it's
(06:37):
an automatic transmission and they're really it's so simple inside,
there's a there's a drive pulley and a driven pulley. Now,
the drive pully is connected to the crankshaft which comes
out of the engine, and the driven pully is the
one that transfers that energy to the drive shaft. Okay, okay,
So crankshaft is the the drive pully. The one that
connects to the drive shaft is the driven pully and
(07:00):
ends as the output between those two. And this is
where it's a little complex there. Um between those two
for automotive purposes, there's a metal belt. It's a it's
a metal belt, which is kind of unique. And now
the belt is is fashioned of several bands that are
run together, maybe a dozen bands, and those are and
that's held together. All those bands are held together with
(07:21):
these um looks like metal keys almost, and there's thousands.
I'm gonna say a thousand, but it's probably more than that,
I'm guessing, because there are that many of them in
this belt. It's very heavy, heavy belt, real heavy duty UM.
And that's what runs between the two pulleys. And we'll
describe the pollis in a second too, But I want
to tell you that a lot of CVTs that use
(07:42):
this pulley system. Um, they don't have to be in cars,
by the way, UM, CVT has been around for a while.
They've been in power tools, drill presses, tractors, snowmobiles, motorcycles,
but they've all used rubber belts in between the pulleys.
And so now the difference is CVTs and cars in
order to handle of the torque on the tower that
you know, and just for durability to use these steel
(08:04):
steel belts. Oh wait, wait, wait one second, no, I
I have to ask you just step back for a second. Um,
how recent or old is this technology? He said, it's
been around for a while, which kind of surprised me.
It's been around a long time. You want to take
a while, I guess do you know? What? Do you
know the answer? Are you just messing with me? Because
(08:26):
if you know, come right out with it, because it's
it's unbelievable when you hear it. Okay, against if I'm wrong.
Leonardo da Vinci really really really blows my mind. Fourteen
ninety is when Leonardo da Vinci, who we've talked about
many times on the program, how he's just just unbelievably advanced. Um,
(08:47):
you know, early thinker. Um, he sketched a stepless continuously
variable transmission in fourteen ninety. If you can believe that,
I mean, I'm trying my best to believe it. I mean,
I have no idea what it looks like. I and
seen this the sketch, um, or how it compares to
what we actually have now. So it had to be
made of wood or something. I don't know. I don't know, stone,
(09:09):
I don't know. I don't really I don't know. Probably
would probably would, and but I don't know. I mean,
I'm guessing vines or something in between the pullies. I
don't Maybe it wasn't a Pulley system. Maybe there's some
other type of system I don't know, four ninety that
would make this uh hundreds and hundreds of years old,
five hundred and twenty years old at this point, something
like that, I mean ballpark. But I guess when you
(09:33):
get down to it, though, it really wasn't built or
or in production, you know, it's not really serving the
purpose that it should. Yeah, that's right. It was conceived
at that point. Um. And you know what, I'm gonna
go earlier than this, I got it. I got to
note here that says nineteen fifty eight, there was a
car that used the CVT in the Netherlands. But um,
(09:53):
I'm gonna go back even further. Then. There's a company
called Zenith Motorcycles and they originated in nineteen o four,
and Zenith Motorcycles had a device that they called a
graduate gear. It's like almost like gradual without the L
at the end. Graduate gear, and it used a variable
(10:13):
pulley system that would vary the length of the drive
belt by moving the rear wheel forward and backward in
its slot. And this apparently gave Zenith Motorcycles a such
a an advantage at the time in this in this
hill climb competition that they were in our hill climb
competitions gave the writers such an advantage that they were
(10:34):
banned from competition. It was that much better than everything
else that was out there. Weird standard standard shift, that's weird.
It's like you heard about the I think they're German.
There's a swimsuit company whose swimsuits have been banned from
professional competitions because the improvement is that noticeable? Is that something?
(10:55):
I mean? I mean, I I say, you know, great,
you know, move on with technology. But um, they held
them back, I guess, but you know, it doesn't didn't
hold them back from producing the motorcycle. They still produced
the motorcycle until I believe it was so after you know,
after World War Two, they were still producing motorcycles just
for a short time and then they went out of business.
But um, early on they were banned from competition because
(11:18):
they had this advantage. And this this technology, as you
said earlier, is is pretty widespread still, right. It was
in power tools, you said, I'll tell you it's in
power tools, it's in snowmobile. A lot of people know
there's some snowmobiles. Um, it's from tractors, drill presses, um, again, motorcycles.
I think there's probably other applications of this, we're just
(11:39):
not seeing them here. Um. But it's it's really kind
of cool. I mean, I'll just get a super basic
description of what it is. Is two pulleys that have
um cone shapes UM to the inside edge of those
those pulleys, and there, of course position right next to
each other. The belt runs between them. The belt always
remains at the same tension, it never gets slack, it
(12:01):
never gets tighter, and when when speeds go up, you know,
one of the sets of pulleys expands and and the
belt rides down further in that in that groove, and
it goes higher up on the groove and the other
pullets at a police So it's this kind of seesaw
back and forth motion. So at higher speeds, the pulley,
you know, on one set of pollis, it will be
(12:21):
you know, riding deeper into that groove, that V shaped
groove that the pulley creates. And on the other set
of pollis then it will always be at the top end.
And I don't mean always, but I mean if it's
low on one end, it's high on the other, and
then it it balances itself out and it just goes
back and forth between the two. So there's a there's
something here that that kind of presents a question to us,
(12:44):
or heavily implies this question. If this technology has been
around for so long, um, is it the norm? It
is becoming the norm? Um. And that is evident in
that there are some manufacturers that al will offer only
manual transmission or a CVT. You can't get an automatic
(13:04):
transmission in some models, not that the manufacturer doesn't offer
an automatic transmission, but you know, that's the that's your option.
Either get a manual transmission, you know, six speed standard shift,
or you get a CBT and go ahead. Well, I
was just gonna I was just gonna say, uh, with
the reference to the manufacturer in the Netherlands, is this
(13:27):
technology more common in one car market than the other,
like Japan or Europe or anything. Actually not, um as
far as I can tell right now. And I couldn't
say for certain whether there are more cars on the
road with CVT in in Europe or in Japan or wherever. UM.
I can tell you though that since well, I mean,
I guess I can just start right here at the beginning.
(13:48):
There was one vehicle sold here in United States that
had a CVT, and that was just the one that
was in nineteen eighty nine Subaru just e g L
and it just never took off, never never really gain
any popular And I don't know if that had anything
to do with the UH CVT or not. I couldn't say.
It's just could have been any of the number of
factors exactly exactly. Now you've got companies like Nissan, and
(14:12):
there's a player Jetco who makes their CVT. That's there's
transmission supplayer. They to date have sold over one million
CVT equipped vehicles. UM, so you can see that. You know,
they're everywhere. I mean they're populating, populating all the continents.
I guess, Um, it's not just Nissan, it's GM, it's Audi,
(14:35):
it's Honda, Nissan, Chrysler. They're all getting into the CVT game.
UM relatively recently, I mean in the last few years.
But um, Nissan has really been kind of leading the
way with this one. I wouldn't say that they were first,
of course they weren't, but um, right now they may
be the ones doing it the best. I've got to
ask one one other thing here that we we actually
(14:58):
we did not we did not talk about earlier. But
what what do you think makes this technology, uh, advantageous
or disadvantageous in comparison to an automatic transmission? Well, um,
it's it's got a smoothness to it that automatics do
not have. Because even in an automatic, you can you
feel that shift. Yeah you still have stepped gears. Yeah
(15:20):
you're right, you still feel that And now I do
a lot of people that's not good. They don't want
to feel that smoothness because it feels like something's wrong.
If you've you've driven a car before where you know
there's slipping clutch or the gears are going through there something,
you know that slipping feeling, and that's what you get
in a CBT equipped vehicle when you when you step
on the gas at a light, you'll hear the engine
(15:42):
kind of spool up. You know, the revs will go up,
but the car doesn't really go anywhere. It's so it's
slowly sorry, it's it doesn't it doesn't match the way
that it feels like it should or that we're accustomed
to it, uh happening, So what if what's happening though,
is it's searching for the right ratio in order to
take off, and then it maintains that proper ratio throughout
the whole drive cycle. So it feels really odd and
(16:05):
it's extremely smooth, and to some people that just doesn't
feel right. Other people kind of blissfully unaware, even don't
even know that, you know, they have a CVT and
everything is just fine. They don't really care. What do
you see as the future of CVT. You know what,
I've been thinking about this one because I knew you're
gonna ask me this I think and and honestly, you know,
(16:28):
I mean I'm surprised that the way I just can't
believe the technology already that we have. I mean, it's
pretty amazing, it really is. When you when you look
at some of the details of these transmissions and what
they can do and what they're capable of. They save fuel,
they're extremely smooth, they're very um, they're very simple. Really inside,
there's not it's not nearly as complex as a standard
(16:48):
automatic transmission. What I would say, um, future developments, I
mean I can only guess, but I mean I'm saying,
like further simplification. Maybe it just refinement of what's already there.
If it can be further simplified, I don't even know
if it can at this point, but never say never.
And um, i'd also say further weight reduction because weight
reduction is um it's so key right now, It's very key.
(17:11):
I mean, it's uh, it's critical when you're talking about
downsizing engine sizes and vehicle weights and you know this
is all part of it. The transmission has to be
reduced as well. I mean, every little bit counts, So
I would say further weight reduction is important. And I
guess use of new materials. I mean, I I can
only think that you know, that would help in weight
reduction and not so much simplification, but new materials might
(17:35):
be one way to go. It's kind of you know,
in these in these episodes, I've noticed we're reaching towards
this is uh, some of the same recommendations again it again,
and those are better materials, higher efficiency, less weight. Yeah,
and you know what, now that we think about maybe
(17:56):
something in the future we could we could go we
could go a little bit deeper into that. Sure all
three are tied together. Um, and the new materials tend
to be lighter the of course that's weight savings and
weight savings increases efficiency. Hey, Scott, are we are we
wrap it up on transmiss you feel like it? You
know what I do. I'm sure there's plenty of questions
(18:18):
out there, so you have had it asked me and
ask me what you like. And also, you know, let's
just say go to the site our our website, how
stuff works dot com and check out the article how
cbt s work and that will clear up a lot
of questions because if you do have questions, their charts, graphs, advantages, disadvantages,
um a lot of a lot of explanation that you know,
we just couldn't go into here. And I also I
(18:41):
urge you to go online and there's a lot of
animations of CVTs in action and that will clear up
a lot of questions you have as well. I mean,
I've watched many of these over I don't know how
many years, I guess, and m to me that just
just being able to see it in action, that really
it makes perfect sense to you once you watch it. Okay, right,
you heard it here first hopefully about how CVTs work.
(19:04):
And as Scott has pointed out, you should definitely check
out the information on the website. While you're there, you
should probably check out his blog, Scott, I don't want
to embarrass you. That's sorry about the Ferrari crash. It's
pretty awesome. Yeah, yeah, there's some there's some disturbing news
about a classic Ferrari, so you want to check out
and there there uh, there's always something on that blog
(19:26):
that is just utterly fascinating. And if you have any questions, comments,
or suggestions for a future episode, please do send us
an email at high Speed Stuff at how stuff works
dot com. Be sure to check out our new video podcast,
Stuff from the Future. Join how Stuff Work staff as
we explore the most promising and perplexing possibilities of tomorrow.
(19:49):
The house Stuff Works iPhone app has arrived. Down with
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