Before the introduction of transmission synchronizers (in the 1920s) and helical cut gears, double clutching was a technique required to prevent damage to an automobile's gear system. Due to the difficulty involved in learning the technique, and because of the advent of synchronized gearing systems, it has largely fallen into disuse. However, drivers of large trucks still use the double clutching technique, as those vehicles are usually equipped with older, more efficient and more durable, unsynchronized gearboxes.

The purpose of the double-clutch technique is to match the rotational speed of the input shaft being driven by the engine to the rotational speed of the gear you wish to select (directly connected to rotating wheels). Once the speeds are matched, the gear will engage smoothly. If the speeds are not matched, the dog teeth on the collar will "crash" or grate as they attempt to fit into the holes on the desired gear. A modern synchromesh gearbox accomplishes this synchronization automatically.