Constant Mesh Gear Box
Constant mesh gearbox is definitely a type of Transmission where all or the majority of the gears are always in mesh with each other, as opposed to a sliding-gear transmission, where engagement is definitely obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear construction and working of constant mesh gearbox ratios are chosen by small Clutches that connect the many gear sets with their shafts to ensure that power can be transmitted through 
them. The next diagram shows the set up of a continuous mesh gear box
Construction and operating of a constant 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, thus not really transmitting power. The gears in both shafts are usually meshed together.
To activate the gears with result shaft dog clutch can be used. the dog clutch can be shifted by the seletor fork shifted 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 result shaft, hence power from lay shaft now transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is 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 gadgets named dog clutches square measure introduced which helps in transmittal the required output to the the majority of shaft by creating connection with the acceptable couple of the meshed gears.
A continuous mesh transmission typically includes 4 forward speeds and 1 reverse manual transmitting configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmitting was an excellent success in vehicles trade as presently there is a system which can provide needed torsion and swiftness ratios need by the automobile to face the road challenges however still there have been several vital problems with this gear 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 since the shifting needed a particular technique that wasn’t whatsoever 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 dual engagement and disengagement of clutch for shifting one particular gear.
f i.electronic. once driver must shift the apparatus he preliminary presses the clutch pedal and produce the apparatus to the neutral, than once again he releases the clutch pedal and accelerate in order to extend the velocity of the lay-shaft in order that the meshing of relevant gear will take place, save for he presses the clutch pedal and create 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 gear 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 Continuous 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 main shaft: one between the clutch gear 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 free to move on it. Dog clutches can slide on the main shaft and rotates with it. All of the gears on the countershaft are completely fixed with it.
When the left dog clutch was created to slide to the 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 left dog clutch meshes with the second gear on the main shaft, the next speed gear is achieved. Similarly, by sliding the right-hand dog clutch to the left and correct, the first speed gear and reverse equipment are attained respectively In this type of gearbox, because all of 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 is used for the smooth operating of an automobile. They are accustomed to increase the rotating pressure (Torque); that is accompanied by a decrease in acceleration. It is a kind of manual transmission. The invention of earliest manual gear system could be traced back again to the nineteenth century. There are multiple equipment ratios present which provides various torque and speed ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed recently contain all of the gears mesh at any provided point of time.
In specialized terms, it could be defined as a gearbox where all of the gears are often in circumstances of mesh. The gears remain fixed at their original positions. The gears will remain engaged all the time. Learn more about its construction, working, advantages, disadvantages and applications in this post.
Construction:
It really 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 rate of the counter shaft may be much less that the rate of the engine. The gear ratio can be explained as the ratio of one’s teeth of driven gear to one’s teeth of the driver gear.
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 relative to the gear ratio.
3. Dog clutch:
Dog clutch is particular feature of continuous mesh gearbox. It is used for the coupling of any two shafts. This is performed 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 may be the transmission of power between your shafts. If the apparatus ratio is several, the primary shaft will work at a rate that is slower compared to the counter shaft, and vice versa. The set up 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 result gears, namely initial, second, third and fourth. Gear ratios can be obtained for each of them. This could be done by the correct sliding of dog clutch over one’s teeth of the chosen gearwheel. After this the road of the energy circulation completes. This happens because of 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 invert gear to the invert idler. The idler wheel will change the path of the rotation. Regarding forwarding direction gear selection, the output gears will rotate in a path opposite to the input gears. However in the case of invert equipment selection, the rotation can be in the same path as the insight shaft.
The steps are taken up to change any gear in the constant mesh gearbox system:
1. The first step when one really wants to modify the gear would be the pressing of the clutch. Following 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 forwards to the first equipment. 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 advantage of the continuous gear mesh is the utilization of helical gears. The double helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are various conditions which might cause harm. Regarding constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. One’s teeth belonging to the apparatus tires stay intact. This is simply not the case for sliding mesh equipment box.
The other equipment boxes are noisy and create an undesired din.
Disadvantages:
It is less efficient compared to the others because of higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is necessary. This is necessary to have 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 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 primary shaft i.electronic. one among the clutch gear and the next gear, and the additional between the first equipment and the reverse equipment.
Your 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 so when the left hand dog clutch was created to slide left by means of the apparatus shift lever, it meshes with the clutch gear and the very best speed equipment is obtained. When the remaining 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 safe from being damaged and irritating grinding sound will not take place while engaging and disengaging.