Constant Mesh Gearbox - Construction, Working, Advantages and Disadvantages

Constant Mesh Gearbox - Construction, Working, Advantages and Disadvantages

For a smooth operation of the engine, the constant mesh gearbox is used. They are used to increase the torque, followed by a speed reduction. The transmission is a kind of manual. The first manual machinery system was invented in the nineteenth century. Different gear ratios have different torque and speed ratios. This is also followed by the reverse process. This newly developed manual transmissions contain all the gear mesh at any time.

It can be described technically as a gearbox in which all gears are always meshed. In the original positions, the gears remain fixed. The gears are constantly engaged. Read more in this article about construction, operating, advantages, drawbacks and applications.

Constant Mesh Gearbox:


It is made up of following components: 

1. Counter shaft or Lay Shaft:

The shaft meets the clutch and the main shaft directly. Without any doubt, the counter shaft speed may be lower than that of the engine depending on the gear ratio. The ratio of gear can be defined as the ratio of the gear teeth to the gear teeth.

2. Main shaft:

The speed of the vehicle operates this shaft. The power is provided by the gears from the counter shaft to the main shaft. This is done according to the ratio of the gear.

3. Dog clutch:

Dog embroidery is a special feature of a continuous mesh transmission. It is used to connect two shafts. This takes place through intervention. Specific gears can be connected to the input and output shafts with a dog clutch.

4. Gears:

The principal function of the gears is the power transfer between the shafts. The main shaft operates at an acceleration that is lenter than the counter shaft and vice versa when the gear ratios are more than one. The reverse and forward gear arrangements are available.


Forward gear selection:

The power starts to flow out of the input shaft and is split into four parts. Each component is equipped with the first, second, third and fourth output gears. For each of them, gear ratios may be obtained. The correct slipping of the dog's clutch over the teeth of the pick gearwheel will make this possible. The energy flow path completes after that. It occurs because the output shaft locking movement.

Reverse gear selection:

The power flows between the input shaft and the reverse gears. The power from the reverse gear is then transmitted to the reverse idler. The idler wheel changes the rotation direction. In the case of selection of transmission direction gears the output gears rotate towards the input gears. But the rotation is in the same direction as the input shaft for the reverse gear collection.

The steps are taken to change any gear in the constant mesh gearbox system:

1. The first step in changing the gear would be to push the clutch. Then comes the neutral condition of the vehicle. The speed of the engine needs to be properly optimized.

2. Another switches to the first gear after the neutral machinery. First speed. First gear. This is known as double embroidery. Inadequate execution of the above steps may result in rough, smooth sound.

Advantages and Disadvantages of Constant Mesh Gearbox:


  • The first and foremost benefit of the constant gear mesh is the utilization of helical gears. The double helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities.
  • There are various conditions which might cause harm. In the case of constant mesh gearbox, any harm is suffered entirely by the dog clutch teeth. The teeth belonging to the gear wheels remain intact. This is not the case for sliding mesh gear box.
  • The other gear boxes are noisy and create an unwanted din.


  • It is less efficient than the others due to higher mesh teeth. Skill is required for it.
  • The double clutch mesh is required. This is required to have the spinning movements of the shaft.

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