Sliding mesh type of gearbox is the oldest type of manual transmission used in automobiles. 

However, in this type the mechanical efficiency was very low and the noise level was quite high. 

Moreover the driver required considerable skill in changing the gears. 

An improvement was achieved in the form of a constant mesh gearbox, which resulted in higher mechanical efficiencies and lower noise level due to the use of helical gears instead of straight spur gears in case of sliding mesh type. 

Still the driver had to adopt double declutching to change gears. 

A further improvement with the help of synchromesh device solve this problem also and these days synchromesh type of gearbox is the universally used type of Automotive manual transmission. 

5 speed synchromesh gearbox employed in 1991 model Mercedes Benz 190D2.5 vehicle is shown in figure.