Does An Automatic Transmission Have a Clutch?

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!


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Chris

6 years of experience
82 reviews
Chris
6 years of experience
Chevrolet Trailblazer L6-4.2L - Not able to change gears - Griffin, Georgia
Chris did an excellent job finding and diagnosing the problem my vehicle was having. He is also to be commended for working with focused diligence. Even though it was raining the whole time he was present performing his diagnostic work he never allowed this to impede his ability to do the required work. I would recommend him without hesitation. He did an excellent job communicating with me as to what he was doing and why.
Mazda Protege - Not able to change gears - Stockbridge, Georgia
Very people friendly and genuinely seemed honest. Acted professional and knowledgeable. I would definitely recommend Chris.

Claud

8 years of experience
475 reviews
Claud
8 years of experience
Cadillac STS V6-3.6L - Not able to change gears - Oak Park, Michigan
Claude is very polite and courteous! He has exceptional knowledge and is very professional! Claude is welcome to working on my automobile every time I request Your Mechanic for my auto needs.
Ford Expedition - Not able to change gears - Detroit, Michigan
Very professional, very thorough and detailed. I was only expecting a diagnostic, Claud was able to get my vehicle running.

Bryant

12 years of experience
596 reviews
Bryant
12 years of experience
Ford Fusion L4-2.5L - Not able to change gears - Indianapolis, Indiana
I had to have Bryant diagnose some transmission issues. The news he gave me at the end was not what I was hoping to hear but pretty much what I expected. He was thorough in explaining what he found with the issue and suggesting options for repair. I’ll definitely consider using him again if I have to have any other services done.

Simon

30 years of experience
19 reviews
Simon
30 years of experience
Nissan Rogue L4-2.5L - Not able to change gears Inspection - Albuquerque, New Mexico
This was my first time using this service so I was a little apprehensive. Simon's communication during the process put me at ease. He was prompt in reaching out the day of the appointment to gather additional information and appraise me of his schedule and ETA. He arrived at the scheduled time and was thorough with his assessment as well as suggesting next steps. Overall, it was a very good experience and his level of knowledge put me at ease. I would highly recommend him to anyone in his service area.

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