page_title: Non-synchronous transmission
hierarchical_section_title: Non-synchronous transmission
caption_attribution_description: English: A crash gearbox with 3 gears and reverse. The 3rd gear is "direct" using doc clutches. (The mechanism is similar to File:Gearbox (Autocar Handbook, 13th ed, 1935).jpg. For the shift pattern see File:Manual Layout 3.svg) Deutsch: Dreigang-Schieberadgetriebe mit Rückwärtsgang. Der dritte Gang ist "direkt". (Der Mechanismus ist ählich zu Abbildung File:Gearbox (Autocar Handbook, 13th ed, 1935).jpg. Das Schaltschema entspricht File:Manual Layout 3.svg))
context_page_description: A non-synchronous transmission— also called a crash gearbox— is a form of manual transmission based on gears that do not use synchronizing mechanisms. They require the driver to manually synchronize the transmission's input speed and output speed.
  Non-synchronous transmissions are found primarily in various types of industrial machinery, such as tractors and semi-tractors. Prior to 1960, most cars used constant-mesh but non-synchronous transmissions.
context_section_description: A non-synchronous transmission— also called a crash gearbox— is a form of manual transmission based on gears that do not use synchronizing mechanisms. They require the driver to manually synchronize the transmission's input speed (engine RPM) and output speed (driveshaft speed).
  Non-synchronous transmissions are found primarily in various types of industrial machinery, such as tractors and semi-tractors. Prior to 1960, most cars used constant-mesh but non-synchronous transmissions.
caption: Non-synchronous "crash" gearbox; commonly used today in semi-tractors and tractors, and formerly used in automobiles pre-1960s