refers to the time interval between gear
changes in a transmission
during which power
delivery is interrupted. This is usually in reference to motor vehicles but can apply to any gearbox
. Reducing shift time is important in performance vehicles or race cars
because during shifting the vehicle is rolling without power to the wheels. Shift time in a manual
gearbox is dependent on the driver but in automatic
cars the electronic mechanism must be tuned to minimize the time between gears.
One method of drastically reducing shift time is to use a Direct-Shift Gearbox
which has two independent clutches
that predict the next gear change making the shift time very small. Using a freewheel
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.
In a manual transmission
car, shift time for upshifts can be reduced by installing a lighter flywheel
. During an upshift the engine revolutions must fall for the same vehicle speed; lighter flywheel will cause the revolutions to drop faster when the engine is unloaded, leading to shorter shift times.