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, where engagement is obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are chosen by small Clutches that connect the many gear sets with their shafts so that power can be transmitted through them. The following diagram shows the set up of a constant 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, hence not construction and working of constant mesh gearbox transmitting power. The gears in both shafts are often meshed together.
To activate the gears with result shaft dog clutch can be used. the dog clutch is usually shifted by the seletor fork shifted by gear lever.To supply invert gearing a idler equipment is used.
When the gear lever is pushed, the gear selector fork pushes your dog clutch. Your dog clutch engages the gear and the result shaft, hence power from lay shaft now 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 as well as the new shifting devices named dog clutches square measure introduced which helps in transmittal the required output to the most shaft by creating contact with the acceptable couple of the meshed gears.
A constant mesh transmission typically comes with 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 vehicles trade as currently there is a system which can offer needed torsion and acceleration ratios really want by the automobile to face the street challenges however still there have been several vital problems 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 an easy task because the shifting needed a 
particular technique that wasn’t whatsoever everybody’s cup of tea, a talented driver was necessary for traveling such vehicle, the special technique needed being Double-de-clutching.
Note – Double-de-clutching- it’s the technique because the name indicates that needed dual engagement and disengagement of clutch for shifting a single gear.
f i.e. once driver must shift the apparatus he initial presses the clutch pedal and produce the gear to the neutral, than once again he releases the clutch pedal and accelerate in order to extend the speed of the lay-shaft in order that the meshing of applicable gear will happen, save for he presses the clutch pedal and produce the apparatus lever to the desired equipment and unleash the clutch pedal and finally the desired 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 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 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 primary shaft: one between your clutch equipment and the second gear; and the various other between the first gear and invert gear. The primary shaft is manufactured splined and all the gears are absolve to move onto it. Dog clutches can slide on the primary shaft and rotates with it. All the gears on the countershaft are completely fixed with it.
When the left dog clutch was created to slide left by using the apparatus shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the remaining dog clutch meshes with the next gear on the main shaft, the next speed gear is achieved. Likewise, by sliding the right-hand dog clutch to the left and correct, the first speed equipment and reverse equipment are obtained respectively In this kind of gearbox, because all the gears are in continuous mesh, they are safe from being damaged and unpleasant grinding sound does not happen while engaging and disengaging them.
Continuous mesh gearbox can be used for the smooth working of an automobile. They are accustomed to increase the rotating power (Torque); that is accompanied by a reduction in rate. It is a kind of manual transmission. The invention of earliest manual equipment system can be traced back to the nineteenth century. There are multiple equipment ratios present which provides 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 provided point of time.
In technical terms, it could be thought as a gearbox where all the gears are always in circumstances of mesh. The gears remain fixed at their first positions. The gears will stay engaged at all times. Find out more about its structure, working, advantages, disadvantages and applications in this post.
Construction:
It is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct contact with the clutch and the primary shaft. Keeping in mind according to the equipment ratio, the acceleration of the counter shaft may be much less that the acceleration of the engine. The gear ratio can be explained as the ratio of the teeth of driven equipment to one’s teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the automobile. The power is made 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 particular feature of constant mesh gearbox. It is utilized for the coupling of any two shafts. This is carried out by interference. Utilizing a dog clutch, different gears can be locked to the result and input shafts.
4. Gears:
The main work of the gears may be the transmission of power between the shafts. If the apparatus ratio is more than one, the primary shaft will work at a acceleration that is slower compared to the counter shaft, and vice versa. The set up of both reverse, along with forward gears, is present.
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 result gears, namely first, second, third and fourth. Gear ratios can be acquired for each of them. This could be done by the proper sliding of dog clutch over the 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 path of the rotation. In the case of forwarding direction gear selection, the result gears will rotate in a path opposite to the input gears. However in the case of invert gear selection, the rotation can be in the same direction as the insight 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 will be the pressing of the clutch. After this comes the neutral condition of the vehicle to be performed. Proper optimization of the engine’s speed is necessary.
2. After the neutral equipment, one moves forwards to the first gear. The first equipment. This process is called dual clutching. Inefficiency in executing the above methods might lead to a severe and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the continuous gear mesh is 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 can cause harm. In the case of constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. The teeth belonging to the apparatus wheels remain 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 compared to the others due to higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is required. This is necessary to possess the spinning motions of the shaft.
Application:
A few of the vehicles which use this type of gearboxes are farm trucks, motorcycles, and large 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 given on the main shaft i.electronic. one among the clutch equipment and the second gear, and the additional between the first equipment and the reverse equipment.
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 is made to slide left by means of the apparatus shift lever, it meshes with the clutch gear and the top speed equipment is obtained. When the left hands dog clutch meshes with second gear, the next gear is obtained.
Similarly, by sliding correct hand dog clutch to the left and right, the 1st 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 secure from being damaged and irritating grinding sound will not happen while engaging and disengaging.
