The 6 main types of car transmission explained (part two)
April 30, 2022
4. Dual-Clutch Transmission
One of the most interesting automatic transmissions found in modern vehicles is the DCT or dual-clutch transmission. This design is best known for its compact size and lightning-fast shifts, which made it popular in sports cars and high-performance vehicles. The DCT is an automatic transmission, but it features two clutches, one for even gears and the other for odd gears. The DCT does not have a torque converter like a conventional automatic. It can change gears very fast since the system can swiftly use one or the other clutch pack connected with the 1-3-5 or 2-4-6 gears.
Volkswagen successfully introduced the DCT in 2003 with the Golf MK4 R32, and it has been subsequently used in many other vehicles. A DCT is lighter than an automatic transmission, which makes it easier to mount in front-wheel-drive models with transversally installed engines. It has also proven durable even for high-performance use and unbeatable in shift times, making it a favorite with the sports car crowd. In most cases, vehicles equipped with a DCT-type gearbox have paddles behind the steering wheel.
5. Sequential Manual Transmission
The sequential manual transmission is rarely used in passenger vehicles but it is a top choice for race car drivers. This highly sophisticated unit uses the feel and control of the manual transmission with the swiftness and precision of an automatic. It is designed for extreme race track use. Sequential manual transmissions have a clutch, but it is only used for starting and selecting the first gear. After that, the driver selects the gears by gear lever or paddle shifts. The driver can concentrate on driving while the gears are changed quickly without the need for pressing the clutch every time.
Despite the benefits, this type of transmission is not used in consumer vehicles because of the high cost. Additionally, there are no skipping gears or “kick down” functions. The sequential manual transmission can only change into the next gear up or down, not skip two or three gears like the common automatic transmission.
6. Semi-Automatic Transmissions
Over the years, numerous companies experimented with hybrids of manual and automatic gearboxes and created the semi-automatic transmission. The basic idea was to combine the efficiency and control of a manual with the comfort of an automatic. So far, semi-automatics have had mixed success and are not commonly used in consumer cars.
The semi-automatics can use a clutch for starting the car, but the rest of the gear changes are done automatically without the driver’s control. The other way is to have a clutch-less design (e.g. Porsche Sportmatic), which is started just like any automatic transmission and then shifted like a manual. Even though the basic concept is sound, semi-automatics proved to be problematic and lack the performance or response of automatic or manual transmissions.
For more information on transmissions and transmission maintenance, consult the knowledgeable technicians at J&H Automotive. The shop is located at 501 W. Tehachapi Blvd., and can be reached at (661) 822-9171.