Types of Gearbox

1. Sliding mesh gearbox
2. Constant mesh gearbox
3. Epicyclic gearbox
4. Synchromesh gearbox
5. Differential gearbox




What is gearbox?

Gearbox is a combination of gears (Type of Gears) and gear trains (Type of Gear Trains) in a box. Gearbox is use for maintain speed ratio in all different condition like load, speed. Gearbox is use in automobile to get different speed ration, velocity ratio and torque ratio.

1. Sliding mesh gearbox

Sliding mesh gearbox


In sliding mesh gearbox a shaft of clutch called as clutch shaft on which rigidly fixed gear is mounted called as clutch gear. Clutch gear is always connected to drive gear of the counter shaft. Counter shaft is fixed shaft which is not movable and sliding. Also three gears are rigidly fixed on counter shaft which is first speed gear, second speed gear and reverse speed gear. Another one shaft is present in gearbox which is movable and sliding called as main shaft. Main shaft is slide with the help of shifter and by sliding main shaft different speed ration can get.

2. Constant mesh gearbox

Constant mesh gearbox


In constant mesh gearbox all gears on main shaft are in constant mesh with corresponding gears of lay shaft or counter shaft. For gear shifting dog clutches are used. Dog clutch is sliding member on main shaft. Two dog clutches are used in constant mesh gearbox. One dog clutch is use between clutch gear and second gear and other dog clutch between first gear and reverse gear. Counter shaft gears are fixed and constantly mesh with gears of main shaft are used to get different speed ratio by dog clutch. Dog clutch shift with the help of shifter and connect with different gears and get different speed ratio.

3. Epicyclic gearbox

In epicyclic gearbox, circular hollow internal teeth gear or drum gear, external teeth centre gear and two or more gears are use. In which centre gear is at centre of drum gear and two or more gears are mounted between centre gear and drum gear and these gears are free to rotate about its own axis and about centre gear, like planet rotate about sun and its own axis also. This arrangement of gears known as epicyclic gear train or planetary gear train, which gives low velocity as well as high velocity. Epicyclic gearboxes are use in automatic gear transmission system like in automobile.

4. Synchromesh gearbox

In modern vehicle, helical gears and synchromesh devices used in gearbox called as synchromesh gearbox. Synchromesh gearbox is similar to constant mesh gearbox, but in synchromesh gearbox synchromesh device used by which two gears to be mesh first come in frictional contact and then equalizes their speed and after then they are engaged smoothly.

5. Differential gearbox

Differential gearbox is widely used in automobile. Differential gearbox is used to transmit motion from propeller shaft to rear wheels. Main purpose of differential gearbox is use in automobile is to transmit different speed ration to both rear wheels that is one rear wheel rotate at different speed and another wheel rotate at different speed. This is very useful while turning an automobile because of one rear wheel turn at lower radius and this wheel cover small distance while turning as compared to other wheel. So that lower radius turning wheel should have low speed and higher radius turning wheel should have high speed.



Recommended Links

  • Type of Gears
  • Type of Gear Trains