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Different types of gearbox explained

Do you find the different types of gearbox all a bit confusing? What's a DCT, or a CVT, or a DSG? We’ve got you covered.

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There was a time when the vast majority of cars in the UK were sold with manual gearboxes. However, as automatic transmissions have improved over the years, so has their popularity.

Today, we are seeing even mainstream models dropping manual gearboxes altogether. They’re still very popular in cheaper cars, as a manual gearbox costs a lot less to build than an automatic transmission, but the next few years could see the traditional stick shift facing extinction.

As the technology has advanced, we’ve seen a variety of different transmissions developed, many gaining their own confusing acronyms. To make life even more unhelpful, car company marketing departments always tend to like adding their own proprietary branding to things, so car buyers can easily get bewildered with it all means.

Here, we’ve put together a list of the most common types of gearbox and an explanation for how they work.

Manual transmission

Let’s start with the classic stick shift, which has been around for many decades. This involves using a gear stick to choose which gear you want to be in. You use a clutch pedal to disengage the gearbox with your left foot and (assuming a right-hand-drive vehicle as used in the UK), you change gears using the lever with your left hand. You then re-engage the clutch to re-connect drive from the car’s engine to its wheels.

One of the key advantages of a manual gearbox is that it gives the driver full control over which gear they want to be in, meaning you can drop a gear to get away quickly or stay in a higher gear to save fuel. Obviously, it also requires a level of skill to engage/disengage the clutch and shift gears whilst driving, making the learning curve steeper than the stop-and-go nature of an automatic transmission.

For modern cars that still offer a manual gearbox, usually you will find either five or six gears to choose from. A few cars, like the Porsche 911 and Aston Martin Vantage, have started to offer seven-speed manual gearboxes in the last couple of years.

A manual gearbox is entirely mechanical, so your hands and feet are directly moving gears and plates. In conjunction with the skills required to change smoothly, this is why a lot of keen drivers still prefer driving with a manual gearbox instead of an automatic.

Automatic transmission

While almost manual gearboxes on road cars follow the same basic principles, automatic transmissions are a whole different thing altogether. Different types of transmissions tend to suit different applications, while some don’t play happily with other mechanical aspects of your car.

Regardless of the mechanical workings going on beneath the surface, any automatic transmission will look pretty familiar to the driver – Park, Reverse, Neutral and Drive, maybe with additional functions like Sport or a manual shift mode.

In decades gone by, the gear lever would physically move the gears around inside the transmission so they needed to be long, thin levers for good leverage, and they looked much the same on any car.

These days, a ‘gear lever’ on an automatic transmission is simply an electronic switch that sends an instruction to the software than manages the gearbox. As a result, we’ve started to see designers choosing to use buttons, paddles or dials instead of old-style levers for controlling the transmission.

All of the different types transmissions detailed below are variations of the automatic gearbox.

Different types of automatic transmission

Torque converter

The torque converter is the “classic” automatic transmission, ha

ving been around since the 1950s and still commonly found in many new cars today.

Instead of using a clutch to disengage the engine from the gearbox when switching gears, it pushes fluid around a sealed case called an impeller. This section transfers the energy from the engine into the fluid, which is then transferred to the output shaft. The number of gears has steadily been increasing over the years, with most modern cars offering anywhere between six and ten speeds.

The advantages of this type of transmission are smooth acceleration from low speeds, as well as high torque at low engine revs. However, the driving experience is generally dulled in comparison with a manual, leading to the common nickname “slushbox”.

Compared to a manual version of the same car, the automatic would traditionally be slower and use considerably more fuel. However, advances in the last couple of decades have led to modern automatic gearboxes often being more economical than an equivalent manual gearbox in most driving circumstances. Reliability is generally pretty good, as you’d expect after 70 years of continuous development. Torque converter transmissions also cope pretty well in heavy-duty situations, so they’re often better than other types of automatic for four-wheel-drive vehicles and for towing.

In the late 1980s, some manufacturers started adding a manual shift option to this sort of transmission so drivers could manually shift up and down through the gears. Although it immediately became a popular feature, in reality the transmission tends to work best if left to its own devices. However, marketing departments couldn’t resist coming up with new names to describe these paddle-shifting automatics, such as:

  • BMW Steptronic
  • Mercedes-Benz Tipshift
  • Mercedes-Benz G-Tronic
  • Porsche/Audi Tiptronic
  • Volvo Geartronic

Single-clutch transmission

The single-clutch transmission first started appearing in the mid-1990s, based on Formula One racing cars that had started using a similar set-up. It was pioneered by Ferrari, which was also the first racing team to use this type of gearbox in F1.

These are sometimes referred to as semi-automatics or automated manuals, because they are essentially built like manual transmissions. They use a traditional clutch to disengage the engine between shifts, but the car does this instead of the driver. Instead the cabin, the gear lever looks like a traditional automatic shift. The driver flicks a paddle/pushes a gear lever and the car handles the rest.

This automated manual set-up tends to weigh a lot less than a traditional torque converter automatic, with a far more direct feel and less of the “slushiness”.

While the theory is great, most manufacturers have struggled to make them work properly. BMW had the best-known example (which it called SMG), but it was known for sluggish, jerky shifts. This type of transmission tends to work better when the driver treats it like a manual and uses the paddles to shift up and down – preferably lifting off the accelerator as you shift, much like you would in a regular manual.

There was plenty of unreliability in single-clutch transmissions for the first decade or so of their existence, which was also partly because they tended to be found in high-performance cars that were driver a fair bit harder than your gran’s Honda Jazz. Newer models tend to be far more robust.

This type of gearbox has now largely been superseded by dual-clutch transmissions. It’s also been known by the following markerting names:

  • Alfa Romeo Selespeed
  • Aston Martin Touchtronic
  • Audi R-Tronic
  • Ferrari F1-Shift
  • Fiat Dualogic
  • Lamborghini e-gear
  • Smart Softip / Softouch

Dual-clutch transmissions (DCT)

This type of gearbox is fast becoming the most common kind of automatic transmission for petrol and diesel cars. Most Volkswagen Group brands – VW, SEAT and Skoda – call it a DSG (direct shift gearbox), although Audi confuses matters further by calling it an S-tronic and Porsche prefers the name PDK, but they’re all the same thing.

As the name suggests, there are two clutches in play with these gearboxes. In its most basic form, there will be two separate clutch systems – one for the odd-numbered gears and another for the even-numbered gears.

The gearbox can therefore pre-select the next gear before a shift happens, which means the shifts are considerably faster than with other types of gearbox. In performance cars, this has been developed to the point where gear changes are almost imperceptible.

This type of transmission offers the same sort of direct feel as a single clutch version, but is usually far smoother and more efficient to drive. It can also usually offer better fuel economy and performance than a manual gearbox. There can still be some jerkiness at low speed, and it can be a bit clunky when moving between first and reverse gears.

Early versions of these gearboxes (mid-late 2000s) were less reliable than later versions from the last decade, and they can be very expensive to fix if they break.

  • Audi S-Tronic
  • BMW/Mini Steptronic (yes, the same name they used on older auto transmissions)
  • Ferrari F1-Shift (yes, the same name they used…)
  • Porsche PDK
  • Volkswagen DSG

Constantly variable transmission (CVT)

This is one of those incredible theoretical technological feats that, in reality, still needs some work – but if manufacturers find a way to make them more pleasant to drive, they will beat all other gearbox types.

A CVT doesn’t have gears at all. Instead, it uses a cone shape with a band around that and another axle. The band can be moved up and down the cone to vary its length and therefore the gear ratio. Theoretically it offers infinitely variable ratios between its upper and lower limit, meaning it can be perfectly optimised for fuel efficiency or performance at any given time. This is particularly helpful for hybrid cars, which can use a CVT to balance the workload between the petrol engine and electric motor.

The downside is a driving experience that tends to feel bizarre and often unpleasant. When accelerating, it feels like the car is pulling against a rubber band. Meanwhile, the accompanying noise has a horrible drone because the revs go straight to the peak power point and stay there as the car picks up speed, rather than rising and falling as you work your way through multiple gears.

This type of transmission is more limited in how it works with modern all-wheel-drive systems than can vary the amount of drive that goes between front and rear wheels, so many AWD cars will use a torque converter or dual-clutch transmission instead.

The latest CVTs from Honda and Toyota do feel much better, so there’s hope for the gearbox yet…

  • Audi Multitronic
  • Subaru Lineartronic

Single-speed transmission

If you’re driving an electric car (or a hybrid vehicle that’s driving in electric mode), then you don’t really have a gearbox at all. That’s because there’s only one gear to transmit energy from the electric motor to the wheels. If you want to go faster, the electric motor spins faster. If you want to go slower, the motor slows down. Simples.

Because there are no gears and a direct connection from engine to wheels, the feeling is smooth and seamless, yet also direct with maximum efficiency.

Additional reporting by Darren Cassey

Stuart Masson
Stuart Massonhttps://www.thecarexpert.co.uk/
Stuart is the Editorial Director of our suite of sites: The Car Expert, The Van Expert and The Truck Expert. Originally from Australia, Stuart has had a passion for cars and the automotive industry for over thirty years. He spent a decade in automotive retail, and now works tirelessly to help car buyers by providing independent and impartial advice.

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