Editing Manual transmission (section)

==Overview==
A manual transmission requires the driver to operate the [[gear stick]] and [[clutch]] in order to change gears (unlike an [[automatic transmission]] or [[semi-automatic transmission]], where one (typically the clutch) or both of these functions are [[Automation|automated]]). Most manual transmissions for cars allow the driver to select any gear ratio at any time, for example shifting from second to fourth gear, or fifth to third gear. However, [[sequential manual transmission]]s, which are commonly used in [[motorcycle]]s and [[racing car]]s, only allow the driver to select the next-higher or next-lower gear.

In a vehicle with a manual transmission, the [[flywheel]] is attached to the engine's [[crankshaft]], therefore rotating at engine speed. A clutch disc sits between the flywheel and the transmission pressure plate which is attached to the transmission input shaft, controlling whether the transmission is connected to the engine or not. The clutch pedal controls the pressure plate (''clutch engaged'' – the clutch pedal is not being pressed) or not connected to the engine (''clutch disengaged'' – the clutch pedal is being pressed down). When the engine is running and the clutch is engaged (i.e., clutch pedal up), the flywheel spins the clutch pressure plate and hence the transmission.

The design of most manual transmissions for cars is that gear ratios are selected by locking selected gear pairs to the output shaft inside the transmission. This is a fundamental difference compared with a typical [[Automatic transmission#Hydraulic automatic transmissions|hydraulic automatic transmission]], which uses an [[epicyclic gearing|epicyclic]] (planetary) design, and a [[torque converter|hydraulic torque converter]]. An automatic transmission that allows the driver to control the gear selection (such as shift paddles or "+/−" positions on the gear selector) is called a [[manumatic]] transmission, and is not considered a manual transmission. Some automatic transmissions are based on the mechanical build and internal design of a manual transmission but have added components (such as [[computer]]-controlled [[actuator]]s and [[sensor]]s) which automatically control the timing and speed of the gear shifts and clutch; this design is typically called an [[automated manual transmission]] (or sometimes a ''clutchless manual transmission'').

Contemporary manual transmissions for cars typically use five or six forward gears ratios and one reverse gear, however, transmissions with between two and seven gears have been produced at times. Transmissions for trucks and other heavy equipment often have between eight and twenty-five gears,{{citation needed|date=June 2020}} in order to keep the engine speed within the optimal [[power band]] for all typical road speeds. Operating such transmissions often uses the same pattern of shifter movement with a single or multiple switches to engage the next sequence of gears.

<gallery class="center" heights="160px" widths="220px" caption="Manual transmissions in operation">
File:Gearbox 4gears.gif|Operation of a constant-mesh 4-speed manual transmission
File:Crash gearbox 3gears and reverse.gif|Non-synchronous "crash" gearbox; with ''sliding-mesh'' design, used in older vehicles
File:Gearbox 4gears sequential.gif|Operation of a constant-mesh 4-speed sequential manual transmission, commonly used in [[motorcycles]] and [[race car]]s
File:0762 Spinning Levers 04 45 20 00 3mb.webm|1936 film of automobile gearbox
</gallery>