Constant Mesh Gear Box
Constant mesh gearbox can be a type of Transmission where all or the majority of the gears are always in mesh with each other, instead of a sliding-gear transmission, where engagement is certainly obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are selected by small Clutches that connect the many gear sets with their shafts so that power can be transmitted through them. The next diagram shows the arrangement of a constant mesh gear box
Construction and functioning of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. The gears are rigidly fixed in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, therefore not really transmitting power. The gears in both shafts are constantly meshed together.
To activate the gears with output shaft dog clutch can be used. the dog clutch is usually shifted by the seletor fork transferred by gear lever.To supply invert gearing a idler gear is used.
When the apparatus lever is pushed, the gear selector fork pushes the dog clutch. The dog clutch engages the gear and the output shaft, therefore power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is that a type of manual transmission where sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears as well as the new shifting products named dog clutches square measure introduced which helps in transmittal the desired output to the the majority of shaft by creating connection with the acceptable pair of the meshed gears.
A constant mesh transmission typically includes 4 forward speeds and 1 reverse manual transmission configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmitting was a great success in cars trade as currently there is a system which can offer needed torsion and quickness ratios want by the automobile to face the road challenges nevertheless still there were several vital issues with this gear that raised the issue on its effectiveness and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t an easy task because the shifting needed a special technique that wasn’t in any respect everybody’s cup of tea, a talented driver was needed for generating such vehicle, the special technique needed being Double-de-clutching.
Note – Double-de-clutching- it’s the technique since the name indicates that needed double engagement and disengagement of clutch for shifting 1 gear.
f i.electronic. once driver needs to shift the apparatus he initial presses the clutch pedal and generate the gear to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the speed of the lay-shaft to ensure that the meshing of applicable gear will occur, save for he presses the clutch pedal and create the gear lever to the required equipment and unleash the clutch pedal and finally the required gear is obtained.
Since the gears are to be meshed square measure in continuous rotation with a completely different speed compared to the meshing of these gears may cause breakage to the gear teethes or continuous deterioration is there.
The shifting of gears could be a terribly clamant method.High maintenance is necessary as slippy and meshing of gears causes resistance to wear of shafts and gears.
MAIN PARTS
Clutch Shaft.
Lay Shaft or counter Shaft.
Main Shaft.
Dog clutch.
Gears.
There are different types of gears with both spur and helical gears like:
Clutch gear.
First gear.
Second gear.
Reverse gear.
WORKING PRINCIPLE:
In Constant Mesh Gearbox gearbox, all gears of the primary shaft are in constantly meshed with the corresponding gears of the layshaft or countershaft. As well dog clutches are given on the main shaft: one between the clutch gear and the second gear; and the additional between the first gear and invert gear. The main shaft is manufactured splined and all the gears are absolve to move on it. Dog clutches can slide on the main shaft and rotates with it. All the gears on the countershaft are permanently fixed with it.
When the left dog clutch was created to slide to the left by making use of the apparatus shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the left dog clutch meshes with the next gear on the main shaft, the second speed equipment is achieved. Likewise, by sliding the right-hand dog clutch to the left and right, the first speed gear and reverse equipment are acquired respectively In this kind of gearbox, because all the gears are in constant mesh, they are secure from being damaged and unpleasant grinding sound does not occur while engaging and disengaging them.
Continuous mesh gearbox is utilized for the smooth operating of an automobile. They are accustomed to increase the rotating push (Torque); that is accompanied by a reduction in quickness. It is a kind of manual transmitting. The invention of earliest manual gear system can be traced back to the nineteenth century. There are multiple equipment ratios present which gives various torque and speed ratio. Along with this, the reverse mechanism is also present. This manual transmissions which are developed lately contain all the gears mesh at any given point of time.
In specialized terms, it can be defined as a gearbox where all the gears are often in circumstances of mesh. The gears stay fixed at their first positions. The gears will remain engaged at all times. Learn more about its structure, working, advantages, disadvantages and applications in this article.
Construction:
It really is made up of subsequent components:
1. Counter shaft or Lay Shaft:
This shaft is in direct connection with the clutch and the primary shaft. Remember according to the gear ratio, the speed of the counter shaft could be less that the acceleration of the engine. The apparatus ratio can be defined as the ratio of one’s teeth of driven equipment to the teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the automobile. The power is made available to the main shaft through the gears from the counter shaft. That is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is special feature of continuous mesh gearbox. It is used for the coupling of any two shafts. That is carried out by interference. Using a dog clutch, different gears can be locked to the result and input shafts.
4. Gears:
The primary work of the gears may be the transmission of power between your shafts. If the gear ratio is several, the main shaft will work at a quickness that is slower than the counter shaft, and vice versa. The arrangement of both reverse, in addition to forward gears, is present.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is divided into four parts. Each component goes to one of the output gears, namely first, second, third and 4th. Gear ratios can be obtained for each of them. This is often done by the proper sliding of dog clutch over one’s teeth of the chosen gearwheel. After this the road of the energy stream completes. This happens due to the locking movement of the result shaft.
Reverse gear selection:
The energy will flow from the input shaft to the reverse gears. The power is after that transmitted from the invert gear to the invert idler. The idler wheel changes the path of the rotation. Regarding forwarding direction gear selection, the result gears will rotate in a direction opposite to the input gears. However in the case of invert gear selection, the rotation can be in the same path as the input shaft.
The steps are taken to change any gear in the continuous mesh gearbox system:
1. The first step when one wants to modify the gear would be the pressing of the clutch. After this comes the neutral state of the automobile to be achieved. Proper optimization of the engine’s speed is necessary.
2. After the neutral gear, one moves forwards to the first gear. The first equipment. This process is called dual clutching. Inefficiency in performing the above techniques might lead to a harsh and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost benefit of the constant gear mesh may be the utilization of helical gears. The double helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are many conditions which can cause harm. In the case of constant mesh gearbox, any harm is suffered entirely by your dog clutch teeth. One’s teeth belonging to the gear wheels stay intact. This is not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an undesired din.
Disadvantages:
It really is less efficient than the others due to higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is required. This is necessary to have the spinning actions of the shaft.
Application:
Some of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this type of gearbox, all of the gears of the main shaft are in constant mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are given on the main shaft i.e. one in between the clutch gear and the next gear, and the various other between the first gear and the reverse gear.
Your dog clutch can slide on the shaft and rotate with it. While, all the gears on the counter shaft are rigidly set with it.
As and when the left hands dog clutch is made to slide to the left by means of the gear shift lever, it meshes with the clutch equipment and the top speed gear is obtained. When the remaining hand dog clutch meshes with second equipment, the next gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the first speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in continuous mesh and hence because of this, they are safe from being damaged and irritating grinding sound will not happen while engaging and disengaging.

Are you curious about construction and working of constant mesh gearbox?