The sliding mesh type gearbox is a manual selective gearbox used in older vehicles. E-type gearboxes have a very simple construction method. The rotation of the engine is transmitted to the gearbox via the clutch shaft.
Inside the gearbox, the gears are mounted on three shafts: the main shaft, the lay shaft and the clutch shaft.
The clutch shaft is meshed between the gear and the lay shaft gear.
The gears on the le shaft are always firmly fixed on the shaft. The gears on the main shaft are mounted in such a way that they move horizontally, but rotate the shaft together.
The required gear ratio is produced by moving the main shaft gears over the splines using the selector mechanism or by connecting the gears on the lay shaft or the main shaft directly to the clutch shaft.
The gears required for the first, second and top gear positions are provided on the main shaft. Main shaft gears can rotate with the main shaft and move the shaft forward and backward.
The idler gear provided between the main shaft gear and the lay shaft gear is used to provide the reverse position.
Now let's see how different gear ratios are created by making different gear ratios in the sliding mesh gearbox:

First gear.

First gear state is made possible by rotating the largest gear on the main shaft with the smallest gear on the shaft, based on the principle that when the larger gear is rotated with smaller gears, the rotational speed decreases but the torque increases when the smaller gear is transferred to the larger gear.
This causes the torque to be too high but slows down as the engine slows down proportionally without turning.

Second gear.

When small gears are rotated with large gears, the rotational speed increases when the torque in the large gear is transferred to the smaller gear but the torque decreases proportionally, thus making the small gear on the main shaft shift the larger gear on the lower shaft to the second gear state.

Top gear.

The top gear condition is created by meshing the gear on the main shaft directly with the gear on the clutch shaft. It uses a main shaft and a rotating direct drive at the same speed as the engine.

Reverse gear.

Reverse gear is used to rotate the main shaft in the opposite direction to the engine rotation and move the vehicle backwards.
The large gear on the main shaft used for first gear is also used for reverse gear. The main shaft rotates the gear in the opposite direction to the clutch shaft as the idler gear is provided between the smaller gears on the le shaft.

Features and disadvantages of sliding mesh gearboxes.

1. Simple construction.
2. Inefficiency.
3. Excessive noise when working.
4. Only drivers with experience working properly can use it properly.