In case of sliding mesh gearbox, the output shaft gears continually rotate with the output shaft while in other gearbox, the output shaft gears are mounted with bearings hence these gears rotates separately. Dual-clutch automatic gearboxes started to appear in road autos in 2003, notably during the Audi TT and https://gearbox-auto30852.blogdal.com/34237804/gearbox-auto-secrets