Skip the auto shop - Our mechanics make house calls

Does An Automatic Transmission Have a Clutch?

Clutch In Automatic Car

Most of the time we think of a clutch in the context of a manual transmission. An automatic transmission does have a clutch system, but usually only a mechanic would refer to it as such. Your automatic transmission performs the same function as a manual transmission – it just does it a little differently.

Automatic transmission basics

Automatic transmissions contain an amazing amount of parts, all of which come together in what’s known as a torque converter system. Your engine and your transmission meet at the bell housing, which contains a torque converter for automatic cars, as opposed to a clutch for a manual transmission. The torque converter connects the engine and the transmission so that the wheels will turn. Planetary gear sets provide the different gear ratios.

The torque converter contains a turbine, an impeller, a stator, and a lock-up clutch (so there you go – your automatic transmission DOES contain a clutch). The impeller is part of the housing of the torque converter, and is connected to the engine. It drives the turbine by means of transmission fluid, and then returns the fluid from the turbine.

Meanwhile, the stator is resting between the turbine and the impeller, minimizing churning loss and increasing torque output by redirecting the fluid from the turbine to the impeller, helping it to move and adding to motor torque. The stator can only rotate one way, so it either rotates with the impeller or doesn’t move at all. The stator gives you more torque when you’re at idle, but not when you’re at highway speed.

Planetary gear set

Now you know how the engine delivers power to the transmission. But how does your automatic transmission change gears? It does it by means of a planetary gear set. It gets its name because it consists of a main, or sun, gear in the middle. There are other gears that rotate around the sun, a planet carrier that connects them, and a ring gear that meshes with the planet gears. The whole system works on the principle of using clutches and brakes to keep various components from moving, so you can change your gear ratio without needing to engage different gears, as you would with a manual transmission – they’re already engaged for you. We could go into much greater detail here, but you have the basics at this point.

The fluid pump

Now, how exactly do clutches and brakes in an automatic car work to change the gears? The key is the fluid pump, working along with the torque converter. The torque converter essentially drives the fluid pump, and the pressure coming from the pump activates the brakes and clutches in the planetary gear set. A rotor spins in the pump housing and creates chambers that create a change in volume. As the volume decreases, the fluid is either pumped or compressed as the gears mesh. Then hydraulic signals are sent to your automatic transmission, by means of clutches and band brakes, locking the torque converter.

Mechanics spend weeks in class learning about automatic transmissions. This is essentially a brief overview to outline a bit about how an automatic transmission works, and to answer the question “does an automatic transmission have a clutch?” Yes, it does!

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Symptoms of a Bad or Failing Flexible Clutch Hose
Common signs include difficulty shifting, low clutch fluid, and feeling no resistance at the clutch pedal.
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...


Related questions

Q: Why no brakes

I would first recommend checking the brake fluid level. There needs to be ample brake fluid in the system to so that there is not a lack of hydraulic pressure. Secondly, check to be sure you do not have vacuum...

Q: What Do Transmission Error Codes Tell You?

Using transmission error codes is a necessary procedure for a transmission technician since automatic transmissions have been computer controlled for over 20 years. The transmissions currently in use are very different to diagnose and repair than transmissions from decades ago....

Q: How do I use driver shift control (DSC)?

Driver shift control (DSC) allows you to control the shifts in your automatic vehicle. This can make for a smoother ride and greater fuel efficiency, and is also more enjoyable for many drivers. You can use the DSC anytime that...