Constant Mesh Gear Box
Constant mesh gearbox is usually a type of Transmission where all or most of the gears are always in mesh with one another, instead of a sliding-gear transmission, in which engagement is definitely obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are chosen by little Clutches that connect the various gear sets with their shafts to ensure that power is transmitted through them. The next diagram shows the arrangement of a continuous mesh gear box
Construction and functioning of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power transmission. The gears are rigidly set in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, thus not really transmitting power. The gears in both shafts are always meshed together.
To activate the gears with result shaft dog clutch can be used. the dog clutch is certainly shifted by the seletor fork transferred by gear lever.To provide invert gearing a idler equipment is used.
When the apparatus lever is pushed, the apparatus selector fork pushes your dog clutch. The dog clutch engages the apparatus and the output shaft, therefore power from lay shaft at this point transmitted to result shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is that a type of manual transmission in which sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears and also the new shifting products named dog clutches square measure introduced which helps in transmittal the desired output to the many shaft by creating connection with the acceptable couple of the meshed gears.
A constant mesh transmission typically comes with 4 forward speeds and 1 reverse manual tranny configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmission was a great success in vehicles trade as construction and working of constant mesh gearbox currently there was a system which can offer needed torsion and velocity ratios desire by the automobile to face the road challenges however still there have been several vital problems with this gear that raised the issue 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 special technique that wasn’t in any respect everybody’s cup of tea, a talented driver was necessary for driving 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 a single gear.
f i.electronic. once driver needs to shift the gear he preliminary presses the clutch pedal and generate the apparatus to the neutral, than once again he releases the clutch pedal and accelerate so as to extend the acceleration of the lay-shaft to ensure that the meshing of relevant gear will take place, save for he presses the clutch pedal and produce the gear lever to the required equipment and unleash the clutch pedal and at last the required gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a completely different speed compared to the meshing of those gears may cause breakage to the apparatus teethes or continuous deterioration is there.
The shifting of gears is actually a terribly clamant method.High maintenance is needed 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 main shaft are in constantly meshed with the corresponding gears of the layshaft or countershaft. Too dog clutches are provided on the primary shaft: one between your clutch equipment and the next gear; and the other between the first gear and reverse gear. The primary shaft is manufactured splined and all of the gears are absolve to move onto it. Dog clutches can slide on the primary shaft and rotates with it. All of the gears on the countershaft are completely fixed with it.
When the left dog clutch is made to slide left with the help of the gear shift lever, it meshes with the clutch gear and the very best speed gear is obtained. When the still left dog clutch meshes with the second gear on the primary shaft, the second speed equipment is achieved. Similarly, by sliding the right-hand dog clutch to the left and correct, the first speed gear and reverse equipment are acquired respectively In this kind of gearbox, because all of the gears are in constant mesh, they are secure from being broken and unpleasant grinding sound does not take place while engaging and disengaging them.
Constant mesh gearbox is utilized for the smooth functioning of a car. They are accustomed to increase the rotating force (Torque); that is accompanied by a decrease in speed. It is a type of manual transmitting. The invention of earliest manual equipment system can be traced back to the nineteenth century. There are multiple gear ratios present which gives various torque and swiftness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed lately contain all of the gears mesh at any provided point of time.
In specialized terms, it can be thought as a gearbox where all of the gears are generally in circumstances of mesh. The gears stay fixed at their original positions. The gears will stay engaged at all times. Learn more about its structure, working, advantages, drawbacks 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 main shaft. Remember according to the equipment ratio, the acceleration of the counter shaft could be less that the velocity of the engine. The gear ratio can be defined as the ratio of the teeth of driven equipment to the 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. That is done relative to the gear ratio.
3. Dog clutch:
Dog clutch is particular feature of constant mesh gearbox. It is used for the coupling of any two shafts. This is carried out by interference. Using a dog clutch, numerous gears could be locked to the result and input shafts.
4. Gears:
The main work of the gears is the transmission of power between the shafts. If the apparatus ratio is several, the main shaft will work at a speed that is slower than the counter shaft, and vice versa. The set up of both reverse, along with forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is divided into four parts. Each part goes to one of the output gears, namely initial, second, third and 4th. Gear ratios can be acquired for each of them. This could be done by the correct sliding of dog clutch over one’s teeth of the selected gearwheel. After this the path of the energy stream completes. This happens due to the locking motion of the result shaft.
Reverse gear selection:
The power will flow from the input shaft to the reverse gears. The power is after that transmitted from the reverse gear to the reverse idler. The idler wheel changes the direction of the rotation. In the case of forwarding direction gear selection, the output gears will rotate in a path opposite to the insight gears. But in the case of invert equipment selection, the rotation is in the same path as the input shaft.
The steps are taken up to change any gear in the continuous mesh gearbox system:
1. The first step when one wants to modify the gear will 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 equipment, one moves ahead to the first equipment. The first equipment. This process is known as dual clutching. Inefficiency in carrying out the above guidelines might result in a severe and gnashing sound.
Advantages and Disadvantages of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh may be the usage of helical gears. The dual helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are numerous conditions which might 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 apparatus wheels remain intact. This is not the case for sliding mesh gear box.
The other equipment boxes are noisy and create an unwanted din.
Disadvantages:
It really is less efficient compared to the others due to higher mesh teeth. Skill is required for it.
The dual clutch mesh is required. This is required to possess the spinning actions of the shaft.
Application:
Some of the vehicles which use this type of gearboxes are farm trucks, motorcycles, and large machinery.
In this type of gearbox, all of 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.e. one in between the clutch equipment and the second gear, and the additional between the first gear and the reverse equipment.
Your dog clutch can slide on the shaft and rotate with it. While, all the gears on the counter shaft are rigidly fixed with it.
As so when the left hands dog clutch was created to slide left by means of the gear change lever, it meshes with the clutch equipment and the very best speed equipment is obtained. When the left hand dog clutch meshes with second equipment, the next gear is 
obtained.
Similarly, by sliding right hand dog clutch left and right, the initial speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in constant mesh and hence because of this, they are secure from being damaged and irritating grinding sound will not take place while engaging and disengaging.
