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A sequential manual transmission, also known as a sequential gearbox or sequential transmission, is a type of non-synchronous manual transmission used mostly in motorcycles and racing cars. [1] It produces faster shift times than traditional synchronized manual transmissions, and restricts the driver to selecting either the next or previous gear, in a successive order.
A sequential manual transmission is unsynchronized, and allows the driver to select either the next gear (e.g. shifting from first gear to second gear) or the previous gear (e.g., shifting from third gear to second gear), operated either via electronic paddle-shifters mounted behind the steering wheel or with a sequential shifter. This restriction avoids accidentally selecting the wrong gear; however, it also prevents the driver from deliberately "skipping" gears. [2] The use of dog clutches (rather than synchromesh) results in faster shift speeds than a conventional manual transmission. [3] [4]
On a sequential manual transmission, the shift lever operates a ratchet mechanism that converts the fore-and-aft motion of the shift lever into rotation of a Gear shift drum or selector drum (sometimes called a barrel) which has three or four tracks machined around its circumference. [5] Selector forks are guided by the tracks, either directly or via selector rods. The tracks deviate around the circumference and as the drum rotates, the selector forks are moved to select the required gear. [6]
When upshifting or downshifting a sequential manual transmission, there is no need to operate the clutch, which is only required when the vehicle starts. Since the engagement ring (or "dog ring") pushed by the shift fork and moves quick, and the engagement ring begins to transmit power synchronously while it comes into contact, the sequential manual transmission has the shortest shift speed, and the shift time is usually 5 milliseconds or less, so now used in all Formula 1 cars.
A sequential manual transmission is not to be confused with a "sequential" shifting function sometimes fitted to hydraulic automatic transmission, marketed with terms such as "Tiptronic" or "SportShift". This function allows the driver to select the previous or next gear through the use of buttons or a lever (usually near the gear shifter or steering wheel); however, the mechanicals of the transmission are unrelated to a true sequential manual transmission.
Most motorcycles use a sequential manual transmission. The rider controls the gear shifter with their foot, allowing their hands to remain on the handlebars, and gear selection uses a layout of 1 - N - 2 - 3 - 4 - 5 - 6 (for a typical 6-speed gearbox, said as "one down, five up"). [7] However, most modern motor scooters do not use a sequential manual transmission; instead using either a hydraulic automatic transmission, or a belt-driven or chain-driven continuously variable transmission. Underbones, however, often use a semi-automatic transmission with an automatic centrifugal clutch, but will still retain the conventional foot-operated gearshift lever, such as the Honda Super Cub.
The first proper sequential manual gearbox used in a racecar was with the Porsche Type 360 Cisitalia in 1946, [8] followed by the infamously unreliable Queerbox design, pioneered by Richard Ansdale and Harry Mundy, which was used in various Lotus Grand Prix racecars during the late-1950s and early-1960s, beginning with the 1958 Lotus 12, and is technically the first proper "sequential" gearbox used in a racecar. [9] Most racing cars also use a sequential transmission now (via a sequential shift lever, with a mechanical linkage, or electronic paddle-shifters), [10] rather than the old H-pattern stick shift, beginning with the paddle-shifted Williams FW14 Formula One car in 1991, which used a sequential drum-rotation mechanism. [11] [12]
The first modern sequential manual gearbox with a manual shift lever was used in the 1990 Peugeot 905 Group C sports car, followed by the Ferrari 333 SP LMP racecar and CART Champ Cars/Indycars in 1994 and 1996, [13] and then the McLaren F1 GTR, Mercedes-Benz CLK GTR, Porsche 911 GT1, and Panoz Esperante GTR-1 GT1 racecars in 1996 and 1997. This was closely followed by WRC Rally cars in 1997, 1998, and 1999, and also the Porsche LMP1-98, Nissan R390 GT1, Toyota GT-One, and the BMW V12 LM' and LMR Le Mans Prototype racecars in 1998 and 1999.
Touring cars have also used sequential manual gearboxes; starting with the European DTM series in 2000, which used it for 12 seasons, until a switch to a paddle-shift system in 2012. The Australian V8 Supercars series started using sequential manual gearboxes in 2008, after switching from an H-pattern manual gearbox.
NASCAR introduced a 5-speed sequential manual transmission with their Gen-7 car in 2022, after using a conventional 4-speed H-pattern manual transmission for many years. [14] [15] [16] [17]
Due to the high rate of wear and abrupt shifting action, sequential manual transmissions are rarely used in passenger cars, albeit with some exceptions.
An automatic transmission is a multi-speed transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. Vehicles with internal combustion engines, unlike electric vehicles, require the engine to operate in a narrow range of rates of rotation, requiring a gearbox, operated manually or automatically, to drive the wheels over a wide range of speeds.
A transmission is a mechanical device which uses a gear set—two or more gears working together—to change the speed, direction of rotation, or torque multiplication/reduction in a machine.
A manual transmission (MT), also known as manual gearbox, standard transmission, or stick shift, is a multi-speed motor vehicle transmission system where gear changes require the driver to manually select the gears by operating a gear stick and clutch.
A semi-automatic transmission is a multiple-speed transmission where part of its operation is automated, but the driver's input is still required to launch the vehicle from a standstill and to manually change gears. Semi-automatic transmissions were almost exclusively used in motorcycles and are based on conventional manual transmissions or sequential manual transmissions, but use an automatic clutch system. But some semi-automatic transmissions have also been based on standard hydraulic automatic transmissions with torque converters and planetary gearsets.
The modern usage of the automotive term manumatic denotes an automatic transmission that allows the driver to select a specific gear, typically using paddle-shifters, steering wheel-mounted push-buttons, or "+" and "-" controls on the gear selector.
A direct-shift gearbox is an electronically controlled, dual-clutch, multiple-shaft, automatic gearbox, in either a transaxle or traditional transmission layout, with automated clutch operation, and with fully-automatic or semi-manual gear selection. The first dual-clutch transmissions were derived from Porsche in-house development for the Porsche 962 in the 1980s.
A preselector gearbox is a type of manual transmission mostly used on passenger cars and racing cars in the 1930s, in buses from 1940–1960 and in armoured vehicles from the 1930s to the 1970s. The defining characteristic of a preselector gearbox is that the gear shift lever allowed the driver to "pre-select" the next gear, usually with the transmission remaining in the current gear until the driver pressed the "gear change pedal" at the desired time.
The Morgan Aero 8 is a sports car built by Morgan Motor Company at its factory in Malvern Link, England from 2000 until 2018.
The automated manual transmission (AMT) is a type of transmission for motor vehicles. It is essentially a conventional manual transmission equipped with automatic actuation to operate the clutch and/or shift gears.
A transmission control unit (TCU), also known as a transmission control module (TCM), or a gearbox control unit (GCU), is a type of automotive ECU that is used to control electronic automatic transmissions. Similar systems are used in conjunction with various semi-automatic transmissions, purely for clutch automation and actuation. A TCU in a modern automatic transmission generally uses sensors from the vehicle, as well as data provided by the engine control unit (ECU), to calculate how and when to change gears in the vehicle for optimum performance, fuel economy and shift quality.
A gear stick, gear lever, gearshift or shifter, more formally known as a transmission lever, is a metal lever attached to the transmission of an automobile. The term gear stick mostly refers to the shift lever of a manual transmission, while in an automatic transmission, a similar lever is known as a gear selector. A gear stick will normally be used to change gear whilst depressing the clutch pedal with the left foot to disengage the engine from the drivetrain and wheels. Automatic transmission vehicles, including hydraulic automatic transmissions, automated manual and older semi-automatic transmissions, like VW Autostick, and those with continuously variable transmissions, do not require a physical clutch pedal.
Easytronic is the Opel tradename for a type of transaxle-based automated manual transmission or gearbox, as used in some Opel/Vauxhall cars.
The Lotus Elise GT1 is a race car developed for grand tourer-style sports car racing starting in 1997.
Selespeed is the name of an automated manual transmission used in Alfa Romeo cars, developed by Italian company Magneti Marelli and made by Graziano Trasmissioni.
A non-synchronous transmission, also called a crash gearbox, is a form of manual transmission based on gears that do not use synchronizing mechanisms. They require the driver to manually synchronize the transmission's input speed and output speed.
A dual-clutch transmission (DCT) is a type of multi-speed vehicle transmission system, that uses two separate clutches for odd and even gear sets. The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. In car and truck applications, the DCT functions as an automatic transmission, requiring no driver input to change gears.
A motorcycle transmission is a transmission created specifically for motorcycle applications. They may also be found in use on other light vehicles such as motor tricycles and quadbikes, go-karts, offroad buggies, auto rickshaws, mowers, and other utility vehicles, microcars, and even some superlight racing cars.
Car controls are the components in automobiles and other powered road vehicles, such as trucks and buses, used for driving and parking.
The 'Queerbox' was the nickname for an early sequential manual transaxle used by Lotus racing cars of the late-1950s and early-1960s, and was very similar in design and operation to a motorcycle gearbox. It was infamously unreliable.
Motorcycle transmissions and the latest auto-racing gearboxes are of the sequential type
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