Editing Double-clutching (technique) (section)

==History==
{{Unreferenced section|date=April 2013}}
Before the introduction of [[manual transmission#Synchronized transmission|transmission synchronizers]] in 1927,<ref>{{cite web | url=https://www.transmissiondigest.com/synchronization-a-study-in-timing/ | title=Synchronization: A Study in Timing | date=September 2003 }}</ref> double clutching was a technique required to prevent damage to an automobile's gearing during shifts. Due to the difficulty and most often unnecessary redundancy involved in the technique, coupled with the advent of synchronized gearing systems, it has largely fallen into disuse in light vehicles. However, many [[tractor unit]]s are still supplied with an unsynchronised gearbox which requires a double-clutching technique to be used.