Powershifting
Encyclopedia
Powershifting is a method of shifting used with manual transmission
s to reduce the time where the driving wheels are not powered.
Unlike a normal gearchange, or "Granny Shifting" with a manual transmission, in a powershift the driver does not let off the accelerator. The clutch
is briefly depressed while the shift lever is rapidly shifted into a higher gear, keeping the engine in its power band
. This helps the car accelerate faster, but increases the wear on the clutch and the transmission beyond normal levels and shortens the expected life of these components. Flat-shifting may also increase fuel consumption. In most cases, there is a method of cutting the ignition and/or fuel delivery, in a similar fashion to a rev-limiter, which prevents the engine from over-revving when the load from the transmission is removed. Many aftermarket engine management systems provide this functionality as either a standard feature or as an option, usually combined with launch control
.
The technique lends itself especially well to sequential transmissions as found on most motorcycles and some race cars.
This can also be achieved by means of electrically, pneumatically or otherwise powered gearbox accessories, for example in racing (to get even faster shift times) or to support disabled motorists who cannot use the limb in question. In effect, such accessories convert the transmission into a semi-automatic transmission
.
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
s to reduce the time where the driving wheels are not powered.
Unlike a normal gearchange, or "Granny Shifting" with a manual transmission, in a powershift the driver does not let off the accelerator. The clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
is briefly depressed while the shift lever is rapidly shifted into a higher gear, keeping the engine in its power band
Power band
The power band of an engine or electric motor refers to the range of operating speeds under which an the engine or motor is able to operate efficiently...
. This helps the car accelerate faster, but increases the wear on the clutch and the transmission beyond normal levels and shortens the expected life of these components. Flat-shifting may also increase fuel consumption. In most cases, there is a method of cutting the ignition and/or fuel delivery, in a similar fashion to a rev-limiter, which prevents the engine from over-revving when the load from the transmission is removed. Many aftermarket engine management systems provide this functionality as either a standard feature or as an option, usually combined with launch control
Launch control (automotive)
Launch control typically refers to an electronic aid which is used to assist the drivers of various motorsports at the start of a race.Launch control also refers to an electronic setting on many modern sporting saloons and coupes which help the driver accelerate from a standing start, to gain the...
.
The technique lends itself especially well to sequential transmissions as found on most motorcycles and some race cars.
This can also be achieved by means of electrically, pneumatically or otherwise powered gearbox accessories, for example in racing (to get even faster shift times) or to support disabled motorists who cannot use the limb in question. In effect, such accessories convert the transmission into a semi-automatic transmission
Semi-automatic transmission
A semi-automatic transmission is an automobile transmission that does not change gears automatically, but rather facilitates manual gear changes by dispensing with the need to press...
.