Speaker 1: Get in touch with technology with tex Stuff from how
Speaker 1: stuff dot com. Every Hey there, everyone a d Welcome
Speaker 1: to tech Stuff. I'm Jonathan Strickland, and and today we
Speaker 1: wanted to talk about Well, let's let one of our
Speaker 1: listeners decide what we're gonna talk about. This comes from
Speaker 1: Eric via Twitter, and he says, have you guys ever
Speaker 1: done an episode in transmissions? I think it'd be interesting.
Speaker 1: The answer to that is no, we are assuming of
Speaker 1: course he's talking about automotive transmissions. Yes, because he could
Speaker 1: be talking about radio transmissions, in which case we already
Speaker 1: did a podcast on that, but we haven't done one
Speaker 1: on automotive ones, right, because usually we don't actually do
Speaker 1: stuff about automotive technology, because we have a whole separate
Speaker 1: show about that. Yeah, car stuff. Scott and Ben they
Speaker 1: covered actually, let's be fair, Scott covers it, Ben asks questions, Uh,
Speaker 1: and we wouldn't have it any other way. Scott is brilliant,
Speaker 1: Scott Benjamin, he's ourn auto editor here at how Stuff Works,
Speaker 1: and he he's one of those quietly brilliant people who's
Speaker 1: just who's just silent until he just absolutely blazes you
Speaker 1: with something ridiculously intelligent. Yeah, you asked him a question,
Speaker 1: and you're you're still wanted to run deep man? Uh? Yeah,
Speaker 1: he's a he's a he's a force to be reckoned with.
Speaker 1: And we actually checked with them first to see if
Speaker 1: they had done an episode on transmissions, and according to Ben,
Speaker 1: they have not, so we thought, well, heck, we'll tackle
Speaker 1: this one and uh and then maybe Car Stuff will
Speaker 1: will school us later on down the line. But and guys,
Speaker 1: if you have not listened to Car Stuff, go check
Speaker 1: it out. It's it's really for everyone, from someone who
Speaker 1: is a real automotive enthusiast to a newbie who finds
Speaker 1: these card terms to be really really difficult to grasp,
Speaker 1: like me. I mean, I am not a car guy,
Speaker 1: so I really enjoyed them. But I know that people
Speaker 1: who are gear heads, who you know, like to get
Speaker 1: in there and really work on vehicles themselves, they love
Speaker 1: it too. So if you're technical but also extremely clear,
Speaker 1: yeah yeah, so definitely check that out. And and Ben
Speaker 1: kind of acts acts as the voice for the person
Speaker 1: who has no idea what's going on, because that's who
Speaker 1: been is. So let's talk about I mean, he'll be
Speaker 1: the first to admit that. So what are we talking
Speaker 1: about with transmissions. What are transmissions? Why are they necessary?
Speaker 1: What's the deal? Well, first, we have to understand that
Speaker 1: a vehicle, let's say a vehicle with an internal combustion engine,
Speaker 1: gets its power from the engine itself. Right, You're burning
Speaker 1: fuel within that engine, and that engine is putting out
Speaker 1: power in the form of kinetic energy. Now, the trick is,
Speaker 1: how do you make the kinetic energy that's generated by
Speaker 1: the engine make your vehicle move as opposed to just
Speaker 1: making noise or heat or explosions. That would be an
Speaker 1: external combustion engine not a good thing vehicles. Now, So, uh,
Speaker 1: what what's generally going on with a vehicle we're gonna
Speaker 1: take for this podcast. We're gonna specifically focus on a
Speaker 1: five speed manual transmission vehicle that has rear wheel drive. Now,
Speaker 1: there are a lot of different configurations you can have.
Speaker 1: The basic premise of the transmission is the same in
Speaker 1: all of these, but the way it's laid out is
Speaker 1: completely different depending upon the car's configuration. So this just
Speaker 1: for the purposes of this podcast, because we can't cover everything.
Speaker 1: It would be a four hour long pod least, and
Speaker 1: we we we'd eventually say, I don't even know where
Speaker 1: I am anymore, we're gonna keep it fairly simple. So, really,
Speaker 1: the transmission is important for being able to take the
Speaker 1: power that an engine is generating and convert that into
Speaker 1: the kinetic energy that's necessary to get your vehicle moving.
Speaker 1: But before we get too far into that, let's kind
Speaker 1: of look back at why is a transmission even necessary?
Speaker 1: I mean, not beyond the fact that what it does.
Speaker 1: Why do we need something that like a variable transmission?
Speaker 1: Why not just something that converts the energy of an
Speaker 1: engine into to the rotating force of wheels moving right.
Speaker 1: And this this has something to do with with the
Speaker 1: difference between, um, the kind of energy that you want
Speaker 1: to use when you're first starting a car, when you're
Speaker 1: accelerating it from a stop, and when you're speeding up
Speaker 1: later on down the line, right, and when you're when
Speaker 1: you're reaching your top speed as well. Yeah, as it
Speaker 1: turns out, an engine only has a very narrow range
Speaker 1: at which it's operating with its revolutions per minute. Relatively
Speaker 1: narrow range. Uh. And if our vehicles worked within that
Speaker 1: same narrow range, we'd be fine, right, if everything was ideal,
Speaker 1: If somehow the range of the engine and the range
Speaker 1: of the motion of the wheels had a one to
Speaker 1: one ratio, whether it was directly uh, analogous, or you
Speaker 1: had to have some sort of gear shift in there too,
Speaker 1: uh to adjust it. We'd be all right, we wouldn't
Speaker 1: need a transmission, but we really need a wider range.
Speaker 1: And the two things that are really important when it
Speaker 1: comes to operating vehicles, uh, for for the purposes of
Speaker 1: this conversation, are speed and torque. Okay, so so what's
Speaker 1: so what's what? What is torque? Torque is is you
Speaker 1: can think of it as a twisting force. It's a
Speaker 1: rotational force. So whenever you have a wheel turning, Uh,
Speaker 1: it's it's powered, it's that's that's that's torque there. Or
Speaker 1: if you're using a wrench, let's say that you need
Speaker 1: to loosen or tighten a bolt with a wrench, you're
Speaker 1: using torque. It's this rotational force. The the end of
Speaker 1: the wrench is moving in a circle and the bolt
Speaker 1: is acting as sort of the axis of this of
Speaker 1: this pit or a pivot point for this motion. Uh.
Speaker 1: That's torque. And by increasing or decreasing torque, you can
Speaker 1: It's kind of what people talk about when they're talking
Speaker 1: about the grip on the road. Um, you can have
Speaker 1: a vehicle that has really high torque uh and really
Speaker 1: low speed. You can have a vehicle has really has
Speaker 1: speed really low torque. You can have lots of different
Speaker 1: combinations here. So for example, bowl imagine a giant crane
Speaker 1: that you would use in a construction field. All right,
Speaker 1: so it's enormous and it's using wheels, not not treads
Speaker 1: or whatever. Uh, this vehicle is going to have an
Speaker 1: enormous amount of torque applied to the wheels in order
Speaker 1: to move this massive vehicle around. It may not be
Speaker 1: moving quickly, but the torque is really powerful, which means
Speaker 1: that it would require a lot of force to make
Speaker 1: sure that those wheels don't turn if the engine were
Speaker 1: operational and it was being put into drive. So if
Speaker 1: you were trying to hold those wheels still, you would
Speaker 1: have to use an enormous amount of force to counteract
Speaker 1: that torque. You could also have a toy, let's say
Speaker 1: that has a little spinning element to it that spins
Speaker 1: at an incredible rpm. But it doesn't do so very
Speaker 1: with very much torque at all. So if you just
Speaker 1: touched it, it would stop spinning and it would just
Speaker 1: be the lightest touch to counteract that torque. Again, the
Speaker 1: torque is not very strong with that particular device. So
Speaker 1: when we're operating our vehicles, we actually need a fairly
Speaker 1: wide range of torque, which is not something that would
Speaker 1: be possible if we had to work within the narrow
Speaker 1: parameters of what an engine is able to put out
Speaker 1: with that range of our pm. Right, if an engine
Speaker 1: only had one speed, it would get really messy, really fast,
Speaker 1: right and exactly. And you know, the vehicle might operate
Speaker 1: fine in certain conditions, but if you change those conditions
Speaker 1: at all, then you'd be in trouble. And see, that's
Speaker 1: the that's the issue, right because we all know when
Speaker 1: you're out there driving, not everything is a perfectly flat highway.
Speaker 1: You know you're going to have inclines, You're gonna have
Speaker 1: changes in the in the environmental conditions that are going
Speaker 1: to require your vehicle to adjust as you are going
Speaker 1: through them. So that's why you need to have a transmission.
Speaker 1: You have to have something where you can shift to
Speaker 1: a different torque or speed in order to one maintain
Speaker 1: your grip on the road and continue moving at the
Speaker 1: appropriate speed and to operate within the engine's parameters. That's
Speaker 1: one of those reasons why, Like, if you keep revving
Speaker 1: the engine and you're in first gear, you'll see that
Speaker 1: needle go all the way into the red and then
Speaker 1: if you keep that up, you burn out your engine.
Speaker 1: So by shifting, you are actually adjusting torque and speed,
Speaker 1: and by doing that you can keep the needle in
Speaker 1: the the ideal operational Yes, so that's what the transmission
Speaker 1: is for. It's for keeping you in this in the
Speaker 1: sweet spot. And there are, of course manual transmissions, automatic transmissions,
Speaker 1: there are variants of those UM and UH. And while
Speaker 1: we're really focusing on manual transmissions, if we were to
Speaker 1: talk about automatic I think I would have to call
Speaker 1: someone else in because yeah, we would need scotten here,
Speaker 1: because it's a little bit beyond what we are certainly
Speaker 1: our personal technical level with the automotive industry. Not to
Speaker 1: mention the fact that I don't know how I would
Speaker 1: explain it in words without the benefit of pictures. It's
Speaker 1: already given an interpretive dance, and that works less well
Speaker 1: on podcasts. You might you might hear us like with
Speaker 1: by the microphone, but it kind of loses something in
Speaker 1: the translation, right. But so originally automobiles only had two
Speaker 1: forward gears in one reverse, so, but they're the engine
Speaker 1: capacity was much less, so so those narrow ranges were
Speaker 1: kind of okay within two gears. UM. Around the early
Speaker 1: nineteen forties late nineteen thirties, um Ford and Chrysler started
Speaker 1: introducing semi automatic gears that would let you UM. You
Speaker 1: still had to use a clutch, but you could, but
Speaker 1: you could switch between them between the higher gears semi automatically.
Speaker 1: UM in the nineteen fifties, the first full automatics were debuted,
Speaker 1: and UH and then after that, all of the advances
Speaker 1: have been in the in the number of speeds, the
Speaker 1: number of gears that are involved in these transmissions. So
Speaker 1: we went from we went from two up to UH
Speaker 1: four speed manuals, and then six speed manuals started hitting
Speaker 1: the market in the late nineteen eighties. Right, so UH,
Speaker 1: and you might wonder why do you have why why
Speaker 1: do you add more of those divisions, more of those speeds.
Speaker 1: It doesn't necess sarily mean that the vehicle is going
Speaker 1: to go faster than earlier vehicles. It does mean that
Speaker 1: the transitions between between the different speeds or the different
Speaker 1: gears becomes a little more smooth because you've you've refined them,
Speaker 1: you've you've made it a little more precise, all right.
Speaker 1: It lets the engines work less hard at the specific
Speaker 1: task that you were asking them to do at the time.
Speaker 1: Along these lines, just just about a couple of days
Speaker 1: ago as of the recording of this podcast, in mid April,
Speaker 1: GM and four General Motors of course and Ford announced
Speaker 1: that they're going to to work together to develop nine
Speaker 1: and ten speed transmissions. I'm assuming those are automatic transmissions
Speaker 1: at this point, because that sounds like a very large gearshift.
Speaker 1: That will you know, for for consumer vehicles, and that
Speaker 1: will uh, you know, save gas mileage. It could it
Speaker 1: could raise gas mileage by five to ten percent, which
Speaker 1: is you know, not non insignificant, right, and then you're
Speaker 1: talking about decreased environmental impact. There are a lot of
Speaker 1: other benefits that roll out through these, uh some people
Speaker 1: might call them all evolutionary changes, but they can make
Speaker 1: a big difference down the road. Did not mean to
Speaker 1: do a pun there, and one goes out the crystal
Speaker 1: edge accidental puns. We don't we don't need any of those.
Speaker 1: Don't mean to do it, all right, So so you
Speaker 1: might be thinking, all right, how does this whole torque
Speaker 1: shifting thing work. And we're gonna get into the actual
Speaker 1: mechanics literally of it in a little bit, but in general,
Speaker 1: think of two gears, all right. If you have two
Speaker 1: gears of the same size and they are they have
Speaker 1: teeth that interlock. When you turn one gear, the other
Speaker 1: gear is going to turn at that same rate. It's
Speaker 1: going to be the same number of revolutions per minute
Speaker 1: because they are the same size, same same number of teeth,
Speaker 1: all that kind of stuff. Now, let's say that you
Speaker 1: have a large gear and a smaller gear and they
Speaker 1: are interlocking, and you're turning the large gear, that smaller
Speaker 1: gear is going to do more revolutions per minute than
Speaker 1: the large gear. You know, when you go from the
Speaker 1: starting point all the way back around to the starting
Speaker 1: point in the large gear, the small one may have
Speaker 1: turned three or four times, depending upon the ratio between
Speaker 1: the two. Right, same thing. If you have a small
Speaker 1: gear in a large gear and you're turning the small gear,
Speaker 1: you're gonna have to turn that small gear several times,
Speaker 1: you know, to get one of the large gear to
Speaker 1: go around right exactly. And and these these differences in
Speaker 1: speed also result in a difference in torque. So that's
Speaker 1: what's going to become important when we start talking about
Speaker 1: the actual process of shifting and what's going on with
Speaker 1: the transmission. For us to understand that, we're really gonna
Speaker 1: have to take a look at the entire drive train
Speaker 1: of a vehicle, which is both exciting and intimidating to me.
Speaker 1: I think, so, I think it's really cool. It's this
Speaker 1: is this is really entertaining physics to me because I
Speaker 1: have I have. I mean, Jonathan doesn't really drive. No,
Speaker 1: Jonathan doesn't drive. Don't. Don't even bother putting the word
Speaker 1: really in there. Jonathan does not drive. We wait, we
Speaker 1: fortunately have a limitedly robust public transports. I can get
Speaker 1: I can get generally to where I need to go.
Speaker 1: Um uh, And I do drive, but I'm a very
Speaker 1: I'm not I'm not particularly a car person. So but
Speaker 1: this is so, this is going to be an exciting Yes.
Speaker 1: I will ask Lauren about her experiences with manual transmissions
Speaker 1: later on in the podcast, so stay tuned to find
Speaker 1: out about Lauren's own personal adventures with this technology before
Speaker 1: we actually get into how this works in a real
Speaker 1: life setting, what the process is when you're shifting. I
Speaker 1: need to take just a quick break to thank our sponsor.
Speaker 1: All right, let's get back to how transmissions actually work.
Speaker 1: So to do this, we have to look at the
Speaker 1: entire system that makes the car go. All right, and
Speaker 1: and you're you're only interacting in this five speed manual
Speaker 1: transmission that we were talking about with with two bits
Speaker 1: of the clutch and the gearshift. Yeah, yeah, But but
Speaker 1: there's a lot going on under this, Yes, a whole lot.
Speaker 1: And so first we need to just understand what these
Speaker 1: what these different parts are. So you've got your car's engine,
Speaker 1: this is the thing that makes it go. Ultimately, as
Speaker 1: you are depressing the gas pedal, you are putting in
Speaker 1: more fuel to the engine, which is then generating more
Speaker 1: uh power. It creates more kinnetic energy in the form
Speaker 1: of the pistons moving up and down. Those pistons are
Speaker 1: connected to a crank shaft which converts the reciprocating motion
Speaker 1: that's the up and down motion of the pistons into
Speaker 1: rotary motion, meaning it's turning into turning in a circular pattern. Now,
Speaker 1: so the crank shaft goes from the up down motion
Speaker 1: to the rotation motion, which is the very basis of
Speaker 1: everything else that's going to happen. Now, the crank shaft
Speaker 1: connects to a flywheel. Now, the fly wheel transmits this
Speaker 1: rotary rotary motion to a clutch plate, and the clutch
Speaker 1: plate is what eventually connects to that clutch pedal. Yeah. Yeah,
Speaker 1: In fact, there's a pressure plate that is pressed up
Speaker 1: against the clutch plate, right. So the pressure plate, when
Speaker 1: it's in contact with the clutch plate, allows this rotary
Speaker 1: motion to transmit through the rest of the of the
Speaker 1: vehicle's drivetrain. So when these two things are in contact
Speaker 1: with one another. Uh, as long as the engine is going,
Speaker 1: then there is some sort of rotation being transmitted at
Speaker 1: that point, assuming you're not in just a neutral So
Speaker 1: what happens when you hit the clutch, Well, when you
Speaker 1: hit the clutch, the pressure plate rises up off of
Speaker 1: lifts off the clutch plate. Once the pressure plates separates
Speaker 1: from the clutch plate, all power is cut off to
Speaker 1: the rest of the transmission, the rest of the transmission exactly. So,
Speaker 1: so while the engine is still going, uh, it is
Speaker 1: not providing rotary force to the transmission and wheels, which
Speaker 1: is what allows you to shift gears exactly without making
Speaker 1: things explode. All right, this is why you why if
Speaker 1: you're driving a manual, you know, driving stick, you have
Speaker 1: to hit the clutch first because that ends up pulling
Speaker 1: that pressure plate off so that you are able to
Speaker 1: shift gears without making the horrible grinding noise and destroying
Speaker 1: your big brother's vehicle. Uh, I say big brother because
Speaker 1: I know a guy who did do that. Yeah, I
Speaker 1: was not there, thankfully. So assuming that the clutch plate
Speaker 1: and pressure plader are in contact with one another, you
Speaker 1: you have not just hit the clutch um it has
Speaker 1: been providing that rotary motion to the gearbox shaft. Now,
Speaker 1: the gearbox consists of several parts itself. You've got the uh,
Speaker 1: the main well. You've got a lay shaft which is
Speaker 1: connect to that gearbox shaft. You've got a main shaft,
Speaker 1: and you've got several gears attached to both. You also
Speaker 1: have something that's either called a dog clutch or a collar,
Speaker 1: depending upon who you're talking to. And that is what
Speaker 1: is connected to a selector mechanism, which, in the case
Speaker 1: of most vehicles we think of as the stick shift,
Speaker 1: the manual shift. So, uh, the lay shaft is has
Speaker 1: got gears that are are actually part of that shaft.
Speaker 1: They're they're they're splind spleened, spleened. It's probably not the
Speaker 1: correct pronunciation, and I'm going to assume it's splind directly
Speaker 1: to the shaft. In other words, it's got a direct attachment.
Speaker 1: So as the chaft turns, so do the gears. Those
Speaker 1: gears have teeth along the edges and they interlock with
Speaker 1: gears that are on the main shaft. But here's the
Speaker 1: big difference between the gears on the lay shaft and
Speaker 1: the ones on the main shaft. The gears on the
Speaker 1: main shaft are mounted on ball bearings, so they can
Speaker 1: spend freely around the axis of the main shaft without
Speaker 1: actually turning the main shift right. They're just kind of
Speaker 1: ghosting along over it until they become connected to the
Speaker 1: shaft through another piece of technology. Yeah, that would be
Speaker 1: the collar or dog clutch. Now, this is attached directly
Speaker 1: to the main shaft. It can slide to the left
Speaker 1: or right along the main shaft, but if it turns,
Speaker 1: the main shaft turns, so by interlocking the color with
Speaker 1: the side of one of these main shaft gears. Both
Speaker 1: both the collar and into the main shaft gears have
Speaker 1: teeth have teeth along the sides of them so that
Speaker 1: I can interlock. Yeah, exactly, So, so imagine that I
Speaker 1: think of it this way. You've got a gear that's
Speaker 1: got teeth along the outer edge, like a like you
Speaker 1: would see in a typical gear. But you also have
Speaker 1: if you're looking at it from from one of the sides,
Speaker 1: so you're not looking at it headlong, You've turned it sideways,
Speaker 1: so you're looking at it like, you know, like a
Speaker 1: plate you're holding it up, it would have teeth and
Speaker 1: holes along the surface that you're actually looking at, and
Speaker 1: those interlock with the collar or dog clutch, right, they
Speaker 1: kind of sandwich together. Right, So what happens is the
Speaker 1: lay shaft gears turn. That makes the main shaft gears turn,
Speaker 1: and if the collar is is engaged in that particular
Speaker 1: main shaft gear, then the main shaft turns. Uh. I know,
Speaker 1: it sounds really confusing. It's a little difficult to get
Speaker 1: across without having visual effects. We will, by the way,
Speaker 1: link on Facebook two pictures and videos of this, so
Speaker 1: it makes it easier to to to visualize and understand.
Speaker 1: But once you've got that main shaft turning, that's what
Speaker 1: then provides rotary motion to the differential. The differentials job
Speaker 1: is to to turn that rotary motion ninety degrees because
Speaker 1: at this point before you hit the differential, that rotation
Speaker 1: is perpendicular to the wheels, which would not work. You
Speaker 1: wouldn't get the wheels to turn that way. Not very useful. Now, yeah,
Speaker 1: you have to turn that rot rotation, that motion to
Speaker 1: be parallel with the wheels in order to get them
Speaker 1: to turn, so you can go forward or backward, depending
Speaker 1: upon which gear is is engaged. So the differential is
Speaker 1: a set of gears that transmits this ninety degrees, so
Speaker 1: you can do that again. This is your basic five
Speaker 1: speed manual transmission with rear wheel drive. So that's the
Speaker 1: basic layout. But what's going on with the transmission alright?
Speaker 1: So remember I said that you had the lay shaft
Speaker 1: and the main shaft, both which have gears on them.
Speaker 1: So imagine that the lay shaft gears are set ups.
Speaker 1: It's gears that are increasing in size as you go
Speaker 1: from gear one to gear five, and then you have
Speaker 1: that your your final gear on that shaft is for reverse.
Speaker 1: It's about the same size as the one that's going
Speaker 1: to be on the main shaft. Along the main shaft,
Speaker 1: of course, the gears are going to be in reverse
Speaker 1: order of size. So for the small lay shaft gear
Speaker 1: you have a large main shaft gear. The next main
Speaker 1: shaft gear is a little smaller, the next one a
Speaker 1: little smaller and a little smaller. So by the time
Speaker 1: you get to fifth gear, you've got a large lay
Speaker 1: shaft gear and a small main shaft gear. This is
Speaker 1: all because of that that relationship between speed and torque
Speaker 1: I was talking about. So if you've got a small
Speaker 1: lay shaft gear turning a large main shaft gear, that
Speaker 1: means that the larger main shaft gear has more torque
Speaker 1: but less speed. So that's important. When you are accelerating
Speaker 1: from a stop so your car has not started moving,
Speaker 1: you want to engage that small gear on the lay
Speaker 1: shaft to turn the large gear on the main shaft
Speaker 1: so that you will start to accelerate from a stopped position. Now,
Speaker 1: once you start speeding up, you are eventually going to
Speaker 1: require the engine to do more more work than what
Speaker 1: it is comfortable doing. That's when you need to shift
Speaker 1: to second gear, which will be a decrease in torque
Speaker 1: but an increase in speed, And it's because that gear
Speaker 1: ratio has changed. The lay shift gear is a little
Speaker 1: larger for gear too, and the main shaft gears a
Speaker 1: little smaller for gear too. That's where you get that
Speaker 1: change in torque and speed. And this is true for
Speaker 1: for each speed step up, for each gear step up. Yeah, exactly.
Speaker 1: So once you get up to gear five, that's when
Speaker 1: you're going really really fast, but don't yeah, about as
Speaker 1: fast as the engine can hand out without you know,
Speaker 1: having you drive off a cliff dukes of hazard style,
Speaker 1: in which case gravity takes control in your acceleration is
Speaker 1: completely dependent upon that. But that's the general progression. So
Speaker 1: if you're looking at how does the power flow, I'll
Speaker 1: walk you through it one more time. So power goes
Speaker 1: like this, engine to pistons, pistons to crank shaft, crank
Speaker 1: cheft to flywheel, flywheel to gear shaft, gear cheft to
Speaker 1: lay shaft, lay cheft to lay shaft gears, lay shaft
Speaker 1: gears to main shaft gears, main shift gears to the
Speaker 1: dog clutch or color color to main shaft, main shaft
Speaker 1: to differential differential to wheels, and the wheels on the
Speaker 1: bus go round and round. Alternately, the red things connected
Speaker 1: to my wristwatch. Yeah, there you go. And so uh
Speaker 1: when when you are shifting gears. What what's actually happening
Speaker 1: is again you hit the clutch. It then separates the
Speaker 1: power of the engine from the from the gearbox down
Speaker 1: the line, so that allows you to move the collar
Speaker 1: or dog clutch from one of those gears to another.
Speaker 1: And if if you want to visualize it, imagine that
Speaker 1: you've got a horizontal pole and you've got gears going
Speaker 1: from the largest to the smallest end in reverse, which
Speaker 1: is kind of a medium sized gear. I'll get the
Speaker 1: reverse in a minute, because that one's kind of interesting,
Speaker 1: like how do you make it go backwards? You might say, well, um,
Speaker 1: you've got this this range of gears. Between each set
Speaker 1: of two, you've got one of those dog clutches or
Speaker 1: collars that's directly attached to the main shaft, all right,
Speaker 1: so that that collar can move to the left or
Speaker 1: right along this horizontal pole and engage either of the
Speaker 1: two gears that are on either side of it. And there, yeah,
Speaker 1: there's set of these in a in a manual five speed,
Speaker 1: there's going to be three of these collars, right because
Speaker 1: between gears one and two, gears three and four, and
Speaker 1: gears five and reverse, or you know whatever, configuration there are.
Speaker 1: That's that's where the collars would be and they would
Speaker 1: be able to engage either of the two, whichever one
Speaker 1: on either side. So if you're in gear number one
Speaker 1: and you're speeding up to gear number two, hit the clutch,
Speaker 1: the pressure plate comes off, the clutch plate. Power is
Speaker 1: cut off to the from the engine to the transmission exactly. Uh.
Speaker 1: And then as you shift the gear shift from one
Speaker 1: to two, the dog color disengages from one and moves
Speaker 1: into the gear too, locks in place. By that time,
Speaker 1: you've you've left of the clutch and the power gets
Speaker 1: re engaged and it just starts turning or it allows
Speaker 1: that main gear, that main shift gear to turn that
Speaker 1: dog collar at that point it goes. Point is decreased,
Speaker 1: speed is increased, yes, um and uh. And that is
Speaker 1: the grinding that you hear. Actually, if you miss shift,
Speaker 1: it's going to be the teeth on the side of
Speaker 1: the collar against the teeth on the side of the
Speaker 1: main shaft gear that it's trying and failing has nothing
Speaker 1: to do with the lay shaft. That's always going to
Speaker 1: the lay shaft and main and main shift gears are
Speaker 1: always going to be turning at the same general speed
Speaker 1: depending upon how much power you're giving the engine. They
Speaker 1: are not. It has nothing to do with the lay
Speaker 1: shaft at all. It's just that main shaft gear. Although
Speaker 1: in originally in manual transmissions they were called sliding gear transmissions,
Speaker 1: and the main shaft gears were in fact blind to
Speaker 1: the main shaft so so they weren't on those ball bearings.
Speaker 1: They weren't floating along it so um which which meant
Speaker 1: that the grinding noise that you would hear in those
Speaker 1: originals was in fact the teeth of the main shaft
Speaker 1: gears failing to line up and grinding against the lay
Speaker 1: shaft gears. I would imagine you would only have one
Speaker 1: lay shaft gear, and you would have variable main shaft
Speaker 1: gear sizes, and that's what would you know? It would
Speaker 1: just shift along those That's how I would imagine that
Speaker 1: would work. Of course I don't know because I didn't
Speaker 1: look into that. But that's that's my first reaction based
Speaker 1: upon how how the typical five speed manual transmission car works.
Speaker 1: I didn't look that deeply into it, so I can
Speaker 1: I can neither confirm nor deny. I'm sure when of
Speaker 1: my listeners will take me to task and explain how
Speaker 1: I got that completely wrong. That was just me guessing
Speaker 1: from based upon my understanding of the other the other method.
Speaker 1: So so reverse, how does reverse work? Reverse is interesting
Speaker 1: because you actual they have three gears, not just the two,
Speaker 1: not just the lay shaft gear and the main shaft gear.
Speaker 1: There's a tiny little gear in between them, called the
Speaker 1: idler gear. Now, because you have a third gear there
Speaker 1: that's in between two gears, you actually reverse the rotational
Speaker 1: direction for the main shaft gear. So while all the
Speaker 1: other let's let's use you know, clockwise and counterclockwise, while
Speaker 1: all the other main shaft gears maybe turning in a
Speaker 1: clockwise motion based upon your perspective, the reverse one will
Speaker 1: be moving in a counterclockwise motion. Or winter Shans for
Speaker 1: my Shakespearean friends. Because that other, that tiny little gear
Speaker 1: is all that needs to happen to h to reverse
Speaker 1: that motion. This is easy to see if you ever
Speaker 1: have gears just to play with. So if you interlock
Speaker 1: two gears and you and you turn them, you'll see
Speaker 1: that based upon the rotation of one, the rotation together
Speaker 1: is always going to be the same. When you put
Speaker 1: a another gear between them and you turn the first one,
Speaker 1: the third one. The third gear that used to be
Speaker 1: the second gear is now turning in the opposite direction
Speaker 1: as it did before because you've got that that intermediary gear,
Speaker 1: the idler gear. So that's what happens when you switch
Speaker 1: into reverse it uh it the the collar engages with
Speaker 1: the main shaft gear that is being turned by this
Speaker 1: idler gear that in turn is being turned by the
Speaker 1: lay shaft gear. And to everything turn turn, turn, there
Speaker 1: is ask your parents, all right. So that's that's the
Speaker 1: basis for manual transmission. Automatic transmission is a little a
Speaker 1: lot more complicated because we would be talking about planetary gears,
Speaker 1: which include and I'm not making this up for people
Speaker 1: who are unfamiliar with it includes a planet gear, of
Speaker 1: sun gear and a ring gear. But it's all incorporated
Speaker 1: into one component, and it it might as well be magic. Uh,
Speaker 1: it is beyond my ken. I know that Scott understands
Speaker 1: it backwards and forwards, and if he were in this
Speaker 1: room right now, he would just be quietly chuckling to himself,
Speaker 1: not in the mean way, just in his more honey, yeah,
Speaker 1: it's so cute that you're trying kind of way. But
Speaker 1: now comes to the important part of our podcast, Lauren,
Speaker 1: I want to know about your experiences driving a stick
Speaker 1: shift car, because I have none. Yeah. Yeah, the well,
Speaker 1: I've I've never um done a whole lot of time
Speaker 1: driving stick shift cars. This is a very brief series
Speaker 1: of lessons that I received from from from one of
Speaker 1: the first people that I dated, Bob, who was a
Speaker 1: big car enthusiast and was really keen on teaching me
Speaker 1: how to drive stick And so the first time that
Speaker 1: I got into this, yeah, I had driven, I'd driven
Speaker 1: automatics before, so I I was passingly familiar anyway with
Speaker 1: how cars worked. But but I got in and I
Speaker 1: sat down and he was like, all right, well you're
Speaker 1: a neutral, so um, so you're gonna want to disengage
Speaker 1: the clutch And I was like, clutch. Where this was
Speaker 1: where Bob learns that perhaps there's a preliminary lesson that
Speaker 1: needs to be taught before the practical Yeah, it was,
Speaker 1: it was, it was. It was a slow start. Well,
Speaker 1: I have to admit, like I I used to a
Speaker 1: friend of mine every now and then would get a
Speaker 1: chance to drive his mother's car. And his mother's car
Speaker 1: was a manual transmission, and I used to take both
Speaker 1: delight and genuine terror. Uh, the experience of screaming whenever
Speaker 1: he would start to pull out of our high school
Speaker 1: parking lot and halfway through the turn the car starts
Speaker 1: to stall out because he's not he's not handling the
Speaker 1: car properly. Right, there's when when when when you press
Speaker 1: the clutch, there's this you um, you can feel when
Speaker 1: it engages and disengages and um, and you have to
Speaker 1: pay very close attention. I've noticed anyway the cars that
Speaker 1: I've driven to to where that is. And that's when
Speaker 1: you can use the gearshift. And if you miss it,
Speaker 1: then you either stall out or you get that terrible
Speaker 1: grinding noise and you're lucky both. Right, Yeah, And that
Speaker 1: is that is a thing that I'm really I'm really
Speaker 1: awful at. I could. I could always. I was fine
Speaker 1: driving out highways when I could kind of just go
Speaker 1: up to five and hang out there for a long time.
Speaker 1: But but once we got back into into town, I
Speaker 1: would be like, you know what, I'm going to pull
Speaker 1: over into the first gas station, set it into neutral
Speaker 1: and just like leap screaming from the car and allow
Speaker 1: somebody with more experienced handle Wow. Alright, note to self.
Speaker 1: All right, So uh, yeah, I mean and of course
Speaker 1: people there are people who who genuinely love driving driving
Speaker 1: manual transmission cars because they have that sense of they've
Speaker 1: got even more control over the vehicles. Yeah, and you
Speaker 1: really can feel I mean, I I understand it's fun.
Speaker 1: I mean, it's it's it's fun to to get to
Speaker 1: to get to move stuff around and you feel like
Speaker 1: you're a crazy action here and you can feel the
Speaker 1: road better and you feel like you do have more
Speaker 1: control over what the engine is doing. But but in
Speaker 1: stop and go traffic, like for example, every day in Atlanta,
Speaker 1: it's not something that I would particularly relish, right. Yeah. Yeah,
Speaker 1: if you're if you're driving a nice, uh scenic route
Speaker 1: where there's not all that stuff and going might be
Speaker 1: a huge blast. But in in you know, your day
Speaker 1: to day traffic, it might be a little bit more
Speaker 1: of a nuisance over time. Well, that that covers our
Speaker 1: podcast on transmissions. We want to thank Eric for sending
Speaker 1: that request. In we want to remind everyone that feel
Speaker 1: free to ask us to cover various topics. We love
Speaker 1: to get requests. Uh and and you know, whatever topic
Speaker 1: you want, it doesn't have to be tech related because
Speaker 1: we can say no. But You can send us messages
Speaker 1: on email our addresses tex stuff at Discovery dot com,
Speaker 1: or drop us a line on Facebook or Twitter, or
Speaker 1: handle both of those is text stuff, hs W and
Speaker 1: Lauren and I will talk to you again really soon.
Speaker 1: For more on this and thousands of other topics, does
Speaker 1: it has staff works dot com