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Transmission Types Demystified

220px-Manual_Layout.svgWhen I bought my first car (it was a second-hand Simca, known as the French equivalent of the VW Beetle ), there were only two choices when it came to transmissions: manual or automatic, with automatic being the cooler type (contrary to that Greased Lighting earworm from Grease, cars do not come with anything hydromatic or systematic).  You had ordinary gear change levers (for auto or for manual) that were located between the driver and passenger seats beside the handbrake but if you had a bench seat in the front, you had column change.  Bouquets to you if you can drive a manual with column change – not many cars have this these days, but in the words of one driving instructor, if you can drive one of those, you can drive anything.

Today, you have a few more choices that may leave you a bit puzzled. You get paddle-shifting, CVT, tiptronic, geartronic and dual clutch systems as well as good old manual and auto.  Just what are these different types and what do they mean for the driver?

transmission-5speed-gearsManual

This is the good old basic type.  You have three foot pedals and a gear stick to play around with.  To change gear, you step on the clutch, which sets the levers going that disengages one bit of the gear mechanism from the other bit it’s currently connected to. Then you shove the gear lever into the position indicated for the gear you want before releasing the clutch.  You decide when you’re going to change the gear, usually using the number of revs per minute as a guideline.  It’s possible to get it wrong with a full manual system: have the engine revs too low for the gear you’re in and you stall (easier to do in a petrol than in a diesel, which is why I would recommend diesel vehicles for those learning to drive a manual). Alternatively, get the engine revs too high for the gear you’re in and you put stress on the engine by making it spin madly (listen to it scream!) and put your fuel consumption through the roof.

Hands-on drivers of the old school like manual vehicles because the driver is in full control of the power, and an experienced driver who knows the torque and power specs of what they’re driving can get the right revs to get exactly the sort of power or torque they need for a particular situation, such as overtaking, towing or hill driving.

Manual is also the hardest to learn how to handle.  If you learn to drive on something with a manual transmission, going to an auto or some other system is easy.  However, doing it the other way around is hard.  This is why you drop your L-plater in a manual car without all the fancy driver aids so he/she learns how to do it for him/herself.

Automatic

Fully automatic transmission takes the problem of deciding when to change gears out of your hands.  As you decelerate or accelerate, when the engine gets to the right number of revolutions, it changes for you so you don’t stall or redline.  Having one less thing to worry about reduces driver distractions.  You don’t have to worry about pushing the clutch in and out, which means you’ve got a foot free, and you can also keep both hands on the wheel while negotiating a roundabout.

You do, however, get a gear lever.  Obviously, the car can’t read your mind about whether you want to go forwards or backwards if you’re at a standstill, so you have to tell it via the lever.  You can also set the maximum gear you want it to go to when you need to get the revs right to get the power and/or torque YOU want, rather than what the car wants (when overtaking, hill driving or towing, or any combination of the above, although you would be nuts if you tried to overtake while going uphill towing a trailer).  These gear levers also have a Park setting (for parking, obviously, so you don’t roll away when parking on a slope; don’t forget to put on the handbrake and turn the wheels to the kerb as normal) and Neutral (for when you’re waiting forever at traffic lights at a standstill or warming up the engine).

Semi-Automatic

Semiautomatic transmission goes by a multitude of names: manumatic, clutchless manual, automated manual, paddle-flappers, paddle shifters, trigger shifting, tiptronic, geartronic, etc. etc.  There’s nearly as many names as there are marques.  This is kind of like a manual system except you don’t have a clutch pedal to press on.  Instead, when you use the levers (usually mounted on the steering wheel; hence the term paddle shifting or paddle-flappers), the engine goes through the disengage-the-clutch-move-to-new-gear-engage-the-clutch routine by itself.  This gives you the best of both worlds: the ability to get the power and torque you want when you want it, plus a nice smooth gear change.  Many semiautomatics can also go fully automatic if you want them to.

Continuous Variable Transmission (CVT)

In your standard gearing systems (manual, automatic and semiautomatic), you have set discrete gear ratios. You’re either at one gear ratio or you’re at another, like keys on a piano.  Not in a CVT transmission.  This uses a collection of pulleys connected to a belt, and they can change and adjust very flexibly, so there’s no set ratio of gears – it’s more like a fretless bass or a violin than a piano.  Some mechanics have described CVT transmission as being a system that constantly changes gears to whatever’s most efficient.

Smoothness and fuel efficiency are the real benefits of CVT transmission.  I can’t say that I’ve ever driven a car with CVT yet, so I can’t describe what driving one is like exactly. However, they say that the more hands-on type of driver doesn’t like the experiences of the revs staying the same while the car accelerates – it’s been compared to being in a motorboat and they say it’s quite unsettling at first.

If you’ve driven CVT, tell us your experience in the comments.

Dual Clutch

This is not the same as double-clutching, which is something that my mother tried to describe. Instead, with dual clutch, you have what is essentially two gearboxes side by side, one with the odd-numbered gears (1, 3, 5 and 7) and another with the even ones (2, 3, 6 and sometimes 8).  It’s usually part of an automatic or semiautomatic system, so don’t worry – you don’t have two clutch pedals to stomp on.  The two gearboxes work as a tag team: when the odd side disengages, the even side kicks in on the next gear up (think of those dinky old-fashioned weather predictors with the little man and the little woman, where one goes in as the other goes out).  This makes for really, really fast changes, which is great for fuel economy.

Again, I haven’t been lucky enough to drive one of these yet, so I’d be keen to hear from those of you who have and want to share their experiences.

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