Shift time refers to the time interval between
gear
A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic ...
changes in a
transmission. This interval is the time in which
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
delivery is transferred to the next selected gear, and
engine speed is reduced or increased to synchronize the speed of the next gear. Shift time is usually in reference to motor vehicles, but can apply to any gearbox.
Reducing shift time is important in
performance and
racing vehicles because upshifting generally interrupts power delivery to the wheels. Shift time in a
manual gearbox is dependent on the driver, but in
automatic or
automated manual cars, the
electronic
Electronic may refer to:
*Electronics, the science of how to control electric energy in semiconductor
* ''Electronics'' (magazine), a defunct American trade journal
*Electronic storage, the storage of data using an electronic device
*Electronic co ...
or
hydraulic control system must be calibrated and tuned to execute fast gear changes. Generally, a
dual-clutch transmission shifts faster than a standard
hydraulic automatic transmission with a
torque converter
A torque converter is a type of fluid coupling that transfers rotating power from a prime mover, like an internal combustion engine, to a rotating driven load. In a vehicle with an automatic transmission, the torque converter connects the power ...
or a single-clutch
automated manual transmission. This is possible because the DCT can pre-select the next gear and switch between its two separate clutches to the next pre-determined gear, thus reducing shift times. Using a
freewheel
Freewheel mechanism
In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An ...
may reduce shift time, as it may not be necessary to use the clutch. A
shift kit is also intended to reduce the shift time of a manual vehicle.
With a
manual transmission
A manual transmission (MT), also known as manual gearbox, standard transmission (in Canada, the United Kingdom, and the United States), or stick shift (in the United States), is a multi-speed motor vehicle transmission system, where gear change ...
, upshift time can be reduced by installing a lighter
flywheel
A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, as ...
. During an upshift, the engine speed must decrease to synchronize with a higher gear; a lighter flywheel will allow the engine speed to drop more quickly, leading to shorter shift times.
Shift times
*A long shift time is considered anything over 625
milliseconds
A millisecond (from ''milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds.
A unit of 10 milliseconds may be called ...
.
*The average manual car driver takes between 500 ms and 1 s to perform vertical gear changes (i.e. 1st-2nd, 3rd-4th, 5th-6th) and 1 - 2 s to perform horizontal gear changes (i.e. 2nd-3rd, 4th-5th). Shift time is also dependent on gear throws (distance between gears), ease of movement,
ergonomics
Human factors and ergonomics (commonly referred to as human factors) is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Four primary goals of human factors learnin ...
of the
gear stick
A gear stick (rarely spelled ''gearstick''), gear lever (both UK English), gearshift or shifter (both U.S. English), more formally known as a transmission lever, is a metal lever attached to the transmission of an automobile. The term ''gear st ...
, and gearbox condition.
*For reference, the time it takes for a human to blink can be as quick as 100ms
(.1 seconds)
Example upshift times
Please note that manufacturers may have different definitions of shift times.
See also
*
Powershifting
*
Shift kit
References
{{reflist
Automobile transmissions