Most people think that because a car with an automatic transmission does not have a clutch pedal, it doesn't have a clutch, but this is not true.
An automatic car can have a clutch, or to be more exact, multiple clutches, but they are utilized differently than in vehicles with manual transmissions.
In this article, we will go over the basics of automatic transmissions, how they implement clutches in their operation, and briefly go over automatic transmission maintenance and repair.
Automatic transmission clutch kit
Do Autos Have A Clutch?
Depending on the make and model, automatic cars do have a clutch, but the clutch is implemented differently than in a car with a manual transmission.
Most of us are somewhat intuitively familiar with how a clutch is operated in a manual transmission car by pressing down on the clutch pedal to momentarily disengage the clutch to change gears.
An automatic car has no clutch pedal, and a hydraulic pump operates the clutches.
Automatic Transmission Basics
There are four main types of automatic transmissions:
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Hydraulic automatic: hydraulic automatic transmissions are the most common type of automatic transmission on the road today, although they are decreasing in use each year. It implements a series of clutch packs that are engaged by transmission fluid and hydraulic pressure. Nowadays, mostly seen in heavier vehicles like SUVs and trucks.
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Continuously variable transmission (CVT): a CVT transmission can have an infinite range of gear ratios as it is operated on an adjustable pulley system. They have a primary and secondary clutch.
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Dual-clutch transmission (DCT): DCT transmissions use two separate clutches, one for the odd gear sets and one for the even gear sets. Often, it is described as two separate manual transmissions housed together but without requiring driver inputs in most applications. They are becoming increasingly popular, particularly in performance applications.
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Automated manual transmission (AMT): often referred to as a clutchless manual, the AMT transmission is designed similarly to a conventional manual transmission; however, the gear shifting is automated. They are not common in modern cars, being replaced by DCT transmissions in performance applications.
Where Is The Clutch In An Automatic Car?
First off, the clutches are located inside the automatic transmission, whereas on cars with manual transmissions, the clutch is located outside the transmission.
How Many Clutches Does An Automatic Have?
How many clutches an automatic transmission has will depend on the type and model of the transmission.
A CVT transmission typically has two clutches, a primary and a secondary, while a hydraulic transmission with clutch packs generally has somewhere between 4 to 8 clutches.
For example, the GM 4L65E, phased out in 2001, has seven clutches, while the new GM 8L90 has a triple clutch arrangement.
How Does The Clutch Work In An Automatic?
Automatic transmissions can be extremely complicated, and there is a large variation in how their clutches function between the various types and models.
In a hydraulic automatic transmission, power is provided from the engine to the transmission via a torque converter, and the clutches are located along an inner spline. When the various clutch packs are pressurized and engaged, they will turn and make up with gear sets to create different gear ratios.
In a CVT transmission, the clutch pack locks the sun gear with the ring gear in a planetary gear set.
How Long Does Automatic Clutch Last?
Properly maintained automatic clutches will last the vehicle's lifetime if properly maintained.
To maximize the lifespan of your automatic clutch, you must follow the transmission's service schedule as laid out in the vehicle's owner's manual.
Another thing to remember is that a transmission's components will wear prematurely in stop-and-go traffic as opposed to consistent highway driving.
Can A Clutch Go Bad In An Automatic Transmission?
Clutches routinely go bad in automatic transmissions, often due to old transmission fluid, a low transmission fluid level, tough driving conditions, or high mileage.
Conclusion
Automatic cars do indeed have clutches. However, they do not have clutch pedals like those in manual transmission cars. Instead, the clutches are located inside the automatic transmission's housing and are operated by hydraulic pressure rather than a foot pedal like a manual transmission.