Sequential manual transmission
Encyclopedia
A sequential manual transmission (or sequential manual gearbox) is a type of manual transmission
used on motorcycle
s and high-performance cars for auto racing
, where gear
s are selected in order, and direct access to specific gears is not possible.
With traditional manual transmissions, the driver can move from gear to gear, by moving the shifter to the appropriate position. This type of transmission is often referred to as a H-pattern because of the path that the shift lever takes as it selects the various gears. A clutch
must be disengaged before the new gear is selected, to disengage the running engine
from the transmission, thus stopping all torque transfer. In auto racing, this process is slow and prone to human error; hence the development of the sequential transmission. A true sequential transmission will very often use dog clutch
engagement rather than the more usual synchromesh as fitted to a normal H-pattern road car gearbox. Engagement using dogs only requires a very brief interruption of engine torque to complete a shift into any adjacent gear. This allows shifting between gears without the use of the clutch. The clutch would normally be used only for standing starts.
Sequential manual transmissions work by providing the driver with the ability to select the gear directly before or after the gear currently engaged. Usually the shift lever is pulled back to select the adjacent lower gear and pushed forwards to select the adjacent higher gear. On a true sequential gearbox, the shift lever operates a ratchet mechanism that converts the fore & aft motion of the shift lever into a rotary motion. This rotary action turns a selector drum (sometimes called a barrel) which has three or four tracks machined around its circumference. Running in the tracks are the selector forks, either directly, or via selector rods. These tracks deviate around the circumference and as the drum rotates, the selector forks running in the tracks are moved to select the required gear. Only a true sequential transmission has a shift mechanism that operates in this way.
Sequential gearboxes are also used in nearly all modern motorcycle
s as it is too cumbersome to have a conventional H-pattern shifter and would take up too much space in the confines of a motorcycle frame. Having control over the gear shifter, typically with the rider's left foot, frees their hands to operate both the clutch and brake without letting go of the handlebars.
Sequential manual transmissions are true manual transmissions, and should not be confused with automatic transmission
s that provide some degree of user shifting input. One commercial example of this type of automatic transmission is the Tiptronic transmission. User shifting through buttons or lever does not necessarily mean that the transmission is a manual transmission.
cars of the 1990s made the most high-profile debut of this technology in motor sports, and enhanced variations on this theme are still in use in many forms of road racing and drag racing today. The simple push-pull action of the shift mechanism also lends itself to semi-automatic control using either hydraulic or pneumatic actuators—a system often referred to as paddle-shift. Instead of a manual gear lever, the driver is provided with (usually) a pair of flipper paddles on the steering wheel, rally cars often utilize just a double-acting single paddle. Pulling on the right-hand paddle makes an up-shift and pulling on the left-hand paddle makes a down-shift. The paddle-shift system will use a sophisticated electronic control unit to provide the necessary logic to operate the shift mechanism. This type of paddle-shift system fitted to race and rally cars should not be confused with most of the current crop of so-called paddle-shift systems fitted to some high-end road cars. More often than not, these systems are nothing more than conventional automatic transmissions which allow driver input to select the gears.
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
used on motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
s and high-performance cars for auto racing
Auto racing
Auto racing is a motorsport involving the racing of cars for competition. It is one of the world's most watched televised sports.-The beginning of racing:...
, where gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
s are selected in order, and direct access to specific gears is not possible.
With traditional manual transmissions, the driver can move from gear to gear, by moving the shifter to the appropriate position. This type of transmission is often referred to as a H-pattern because of the path that the shift lever takes as it selects the various gears. A clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
must be disengaged before the new gear is selected, to disengage the running engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
from the transmission, thus stopping all torque transfer. In auto racing, this process is slow and prone to human error; hence the development of the sequential transmission. A true sequential transmission will very often use dog clutch
Dog clutch
A dog clutch is a type of clutch that couples two rotating shafts or other rotating components not by friction but by interference. The two parts of the clutch are designed such that one will push the other, causing both to rotate at the same speed and will never slip.Dog clutches are used where...
engagement rather than the more usual synchromesh as fitted to a normal H-pattern road car gearbox. Engagement using dogs only requires a very brief interruption of engine torque to complete a shift into any adjacent gear. This allows shifting between gears without the use of the clutch. The clutch would normally be used only for standing starts.
Overview
Sequential gearboxes are also used in nearly all modern motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
s as it is too cumbersome to have a conventional H-pattern shifter and would take up too much space in the confines of a motorcycle frame. Having control over the gear shifter, typically with the rider's left foot, frees their hands to operate both the clutch and brake without letting go of the handlebars.
Sequential manual transmissions are true manual transmissions, and should not be confused with automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
s that provide some degree of user shifting input. One commercial example of this type of automatic transmission is the Tiptronic transmission. User shifting through buttons or lever does not necessarily mean that the transmission is a manual transmission.
Benefits
Beyond the ease of use from a driver's standpoint, an additional benefit of sequential manual gearboxes is that use of the clutch via foot pedal or hand control can be minimized or completely obviated, with the clutch only used for starting from a complete stop. Formula OneFormula One
Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single seater auto racing sanctioned by the Fédération Internationale de l'Automobile . The "formula" designation in the name refers to a set of rules with which...
cars of the 1990s made the most high-profile debut of this technology in motor sports, and enhanced variations on this theme are still in use in many forms of road racing and drag racing today. The simple push-pull action of the shift mechanism also lends itself to semi-automatic control using either hydraulic or pneumatic actuators—a system often referred to as paddle-shift. Instead of a manual gear lever, the driver is provided with (usually) a pair of flipper paddles on the steering wheel, rally cars often utilize just a double-acting single paddle. Pulling on the right-hand paddle makes an up-shift and pulling on the left-hand paddle makes a down-shift. The paddle-shift system will use a sophisticated electronic control unit to provide the necessary logic to operate the shift mechanism. This type of paddle-shift system fitted to race and rally cars should not be confused with most of the current crop of so-called paddle-shift systems fitted to some high-end road cars. More often than not, these systems are nothing more than conventional automatic transmissions which allow driver input to select the gears.