Constant Mesh Gear Box
Constant mesh gearbox is certainly a kind of Transmission where all or most of the gears are always in mesh with each other, instead of a sliding-gear transmission, in which engagement is definitely obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are chosen by little Clutches that connect the many gear sets to their shafts to ensure that power is definitely transmitted through them. The following diagram shows the set up of a continuous mesh gear box
Construction and working of a continuous mesh gear box
Constant equipment mesh gearbox employed helical gears for power transmission. The gears are rigidly fixed in the lay shaft. The gears in result shaft rotates freely without engaging with shaft, hence not transmitting power. The gears in both shafts are constantly meshed together.
To activate the gears with output shaft dog clutch is used. the dog clutch is certainly shifted by the seletor fork relocated by gear lever.To supply reverse gearing a idler equipment is used.
When the gear lever is pushed, the apparatus selector fork pushes your dog clutch. Your dog clutch engages the gear and the result shaft, thus 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 and also the new shifting devices named dog clutches square measure introduced which helps in transmittal the construction and working of constant mesh gearbox required output to the many shaft by creating contact with the acceptable pair of the meshed gears.
A constant mesh transmission typically comes with 4 forward speeds and 1 reverse manual tranny configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmission was a great success in vehicles trade as presently there was a system which can provide needed torsion and speed ratios need by the automobile to face the street challenges however still there were several vital issues with this equipment that raised the question on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t a simple task because the shifting needed a particular 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 because the name indicates that needed double engagement and disengagement of clutch for shifting one gear.
f i.e. once driver must shift the apparatus he initial presses the clutch pedal and create the apparatus to the neutral, than once more he releases the clutch pedal and accelerate in order to extend the velocity of the lay-shaft to ensure that the meshing of applicable gear will occur, save for he presses the clutch pedal and produce the apparatus lever to the required gear and unleash the clutch pedal and at last the required gear is obtained.
Since the gears are to be meshed square measure in continuous rotation with a totally different speed compared to the meshing of these gears may cause breakage to the gear teethes or continuous wear and tear is there.
The shifting of gears is actually 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 various kinds 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. Too dog clutches are given on the main shaft: one between the clutch equipment and the next gear; and the various other between the first gear and reverse gear. The main shaft is made splined and all the gears are free to move onto it. Dog clutches can slide on the main shaft and rotates with it. All of the gears on the countershaft are permanently fixed with it.
When the left dog clutch was created to slide to the left by using the gear shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the remaining dog clutch meshes with the second gear on the primary shaft, the second speed gear is achieved. Similarly, by sliding the right-hand dog clutch left and right, the first speed gear and reverse gear are attained respectively In this type of gearbox, because all the gears are in constant mesh, they are secure from being damaged and unpleasant grinding audio does not occur while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth working of an automobile. They are used to increase the rotating push (Torque); this is accompanied by a reduction in velocity. It is a kind of manual tranny. The invention of earliest manual equipment system can be traced back again 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 of the gears mesh at any given point of time.
In technical terms, it can be thought as a gearbox in which all the gears are generally in a state of mesh. The gears remain fixed at their primary positions. The gears will remain engaged all the time. Find out more about its building, working, advantages, drawbacks and applications in this article.
Construction:
It is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct connection with the clutch and the main shaft. Keeping in mind according to the equipment ratio, the acceleration of the counter shaft could be less that the quickness of the engine. The gear ratio can be defined as the ratio of one’s teeth of driven gear to one’s teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the vehicle. The power is manufactured available to the primary shaft through the gears from the counter shaft. This is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is unique feature of constant mesh gearbox. It is used for the coupling of any two shafts. That is done by interference. Using a dog clutch, numerous gears can be locked to the result and input shafts.
4. Gears:
The main work of the gears is the transmission of power between your shafts. If the gear ratio is several, the primary shaft will continue to work at a swiftness that is slower than the counter shaft, and vice versa. The set up of both reverse, as well as forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is divided into four parts. Each part goes to among the output gears, namely initial, second, third and fourth. Gear ratios can be acquired for each of them. This can be done by the proper sliding of dog clutch over one’s teeth of the selected gearwheel. After this the path of the energy circulation completes. This happens due to the locking motion of the result shaft.
Reverse gear selection:
The energy will flow from the input shaft to the reverse gears. The energy is after that transmitted from the reverse gear to the invert idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction equipment selection, the result gears will rotate in a path opposite to the insight gears. However in the case of reverse equipment selection, the rotation is definitely in the same direction as the insight shaft.
The steps are taken up to change any gear in the constant mesh gearbox system:
1. The first rung on the ladder when one really wants to modify the gear would be the pressing of the clutch. Following this comes the neutral condition of the vehicle to be achieved. Proper optimization of the engine’s speed is necessary.
2. After the neutral gear, one moves ahead to the first equipment. The first gear. This process is called double clutching. Inefficiency in executing the above actions might result in a severe and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage 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 might cause harm. In the case of constant mesh gearbox, any harm is suffered completely by your dog clutch teeth. The teeth belonging to the gear wheels remain intact. This is not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an unwanted din.
Disadvantages:
It really is less efficient compared to the others because of higher mesh teeth. Skill is required for it.
The dual clutch mesh is necessary. This is required to have the spinning actions of the shaft.
Application:
A few of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and heavy machinery.
In this kind of gearbox, all the gears of the primary shaft are in constant mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are provided on the main shaft i.electronic. one in between the clutch gear and the next gear, and the other between the first gear and the reverse gear.
The dog clutch can slide on the shaft and rotate with it. While, all of the gears on the counter shaft are rigidly set with it.
As and when the left hand dog clutch was created to slide to the left by means of the apparatus shift lever, it meshes with the clutch equipment and the top speed gear is obtained. When the left hands dog clutch meshes with second equipment, the second gear is obtained.
Similarly, by sliding right hand dog clutch left and right, the first speed gear and reverse gear are obtained respectively.
In this kind 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 does not happen while engaging and disengaging.
