Constant Mesh Gear Box
Constant mesh gearbox is definitely a type of Transmission in which all or most of the gears are always in mesh with one another, instead of a sliding-gear transmission, in which engagement is certainly obtained by sliding some 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 with their shafts to ensure that power is certainly transmitted through them. The following diagram shows the set up of a constant mesh gear box
Construction and working of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power transmitting. The gears are rigidly set in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, thus not transmitting power. The gears in both shafts are at all times meshed together.
To activate the gears with output shaft dog clutch is used. the dog clutch is shifted by the seletor fork moved by gear lever.To supply invert gearing a idler gear 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, therefore power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is a kind 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 gadgets named dog clutches square measure introduced which assists in transmittal the desired 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 transmitting configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmission was an excellent success in vehicles trade as presently there was a system which might provide needed torsion and quickness ratios wish by the automobile to face the street challenges nevertheless still there have been 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 particular technique that wasn’t whatsoever everybody’s cup of tea, a talented driver was necessary 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 a single gear.
f i.electronic. once driver must shift the apparatus he preliminary presses the clutch pedal and create the apparatus to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the swiftness of the lay-shaft to ensure that the meshing of relevant gear will occur, save for he presses the clutch pedal and produce the gear lever to the desired 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 will cause breakage to the gear teethes or continuous wear and tear 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 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 primary shaft: one between the clutch gear and the second gear; and the various other between the first gear and reverse gear. The main shaft is manufactured splined and all the gears are absolve 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 is made to slide to the left with the aid of the gear 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 next speed gear is achieved. Likewise, by sliding the right-hand dog clutch left and correct, the first speed equipment and reverse gear are acquired respectively In this kind of gearbox, because all of the gears are in continuous mesh, they are safe from being damaged and unpleasant grinding audio does not take place while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth functioning of an automobile. They are accustomed to increase the rotating push (Torque); that is accompanied by a decrease in acceleration. It is a kind of manual transmission. The invention of earliest manual gear system can be traced back again to the nineteenth century. There are multiple gear ratios present which provides various torque and acceleration ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed recently contain all of the gears mesh at any given point of time.
In technical terms, it could be defined as a gearbox where all of the gears are constantly in circumstances of mesh. The gears stay fixed at their first positions. The gears will remain engaged all the time. Learn more about its construction, working, advantages, drawbacks and applications in this post.
Construction:
It is made up of subsequent 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 gear ratio, the quickness of the counter shaft may be much less that the acceleration of the engine. The apparatus ratio can be explained as the ratio of one’s teeth of driven equipment to one’s teeth of the driver equipment.
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 relative to 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 done by interference. Using a dog clutch, different gears could be locked to the output and input shafts.
4. Gears:
The main work of the gears is the transmission of power between your shafts. If the apparatus ratio is several, the primary shaft will continue to work at a rate that is slower compared to 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 split into four parts. Each component goes to among the result gears, namely first, second, third and 4th. 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 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 then transmitted from the reverse gear to the reverse idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction gear selection, the result gears will rotate in a path opposite to the insight gears. However in the case of invert equipment selection, the rotation is certainly in the same direction as the insight shaft.
The steps are taken to change any gear in the constant mesh gearbox system:
1. The first step when one wants to change the gear will be the pressing of the clutch. After this comes the neutral state of the vehicle to be performed. Proper optimization of the engine’s speed is necessary.
2. After the neutral gear, one moves ahead to 
the first gear. The first gear. This process is called dual clutching. Inefficiency in construction and working of constant mesh gearbox carrying out the above steps might result in a severe and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the continuous gear mesh may be the utilization of helical gears. The dual helical gears and the helical gears are really beneficial due to their quieter operating capabilities
There are many conditions which might cause harm. Regarding constant mesh gearbox, any damage is suffered entirely by the dog clutch teeth. The teeth belonging to the apparatus wheels remain intact. This is simply not the case for sliding mesh gear box.
The other gear boxes are noisy and create an unwanted din.
Disadvantages:
It is less efficient compared to the others because of higher mesh teeth. Skill is required for it.
The double clutch mesh is necessary. This is necessary to possess the spinning actions of the shaft.
Application:
A few of the vehicles designed to use this type of gearboxes are farm trucks, motorcycles, and heavy 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.electronic. one among the clutch equipment and the next gear, and the various other between the first gear 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 to the left by means of the gear change lever, it meshes with the clutch equipment and the very best speed gear is obtained. When the left hand dog clutch meshes with second gear, 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 for this reason, they are safe from being damaged and irritating grinding sound does not occur while engaging and disengaging.
