Constant Mesh Gear Box
Constant mesh gearbox is certainly a kind of Transmission where all or the majority of the gears are always in mesh with each other, instead of a sliding-gear transmission, in which engagement is obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are selected by small Clutches that connect the many gear sets with their shafts so that power is usually transmitted through them. The following diagram shows the set up of a continuous mesh gear box
Construction and working 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 result shaft rotates freely without engaging with shaft, therefore not transmitting power. The gears in both shafts are at all times meshed together.
To activate the gears with result shaft dog clutch is used. the dog clutch can be shifted by the seletor fork shifted by gear lever.To supply reverse 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, hence power from lay shaft today transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is a form 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 desired output to the many shaft by creating connection with the acceptable pair of the meshed gears.
A constant mesh transmission typically includes 4 forward speeds and 1 reverse manual transmission configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmitting was a great success in cars trade as currently there was a system which can offer needed torsion and velocity ratios wish by the vehicle to face the street challenges nevertheless still there were several vital problems with this equipment that raised the question on its performance and responsibility. the problems long-faced were as follows-
The shifting of gears wasn’t an easy task since the shifting needed a particular 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 construction and working of constant mesh gearbox because the name indicates that needed dual engagement and disengagement of clutch for shifting a single gear.
f i.electronic. once driver needs to shift the gear he initial presses the clutch pedal and produce the gear to the neutral, than once more he releases the clutch pedal and accelerate in order to extend the speed 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 desired gear and unleash the clutch pedal and finally the required gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a totally different speed than the meshing of those 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 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. As well dog clutches are provided on the primary shaft: one between your clutch gear and the next gear; and the other between the first gear and reverse gear. The primary shaft is made splined and all the gears are free to move onto it. Dog clutches can slide on the primary 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 left with the aid of 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 primary shaft, the next speed gear is achieved. Similarly, by sliding the right-hand dog clutch 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 broken and unpleasant grinding audio does not take place while engaging and disengaging them.
Constant mesh gearbox is used for the smooth operating of a car. They are used to increase the rotating pressure (Torque); that is accompanied by a decrease in acceleration. It is a kind of manual transmitting. The invention of earliest manual gear system can be traced back again to the nineteenth century. There are multiple gear ratios present which gives various torque and quickness ratio. Along with this, the reverse mechanism can be present. This manual transmissions which are developed lately contain all of the gears mesh at any given point of time.
In specialized terms, it can be defined as a gearbox where all of the gears are always in circumstances of mesh. The gears remain fixed at their first positions. The gears will remain engaged at all times. Find out more about its building, working, advantages, drawbacks and applications in this post.
Construction:
It really 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. Remember according to the gear ratio, the quickness of the counter shaft may be less that the swiftness of the engine. The apparatus ratio can be explained as the ratio of the teeth of driven equipment to the 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 in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is special feature of continuous mesh gearbox. It can be used for the coupling of any two shafts. That is completed by interference. Utilizing a dog clutch, numerous gears could 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 continue to work at a speed that is slower compared to the counter shaft, and vice versa. The arrangement 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 acquired for each of them. This is often done by the proper sliding of dog clutch over the teeth of the selected gearwheel. After this the road of the energy circulation completes. This happens because of the locking movement 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 invert gear to the invert 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 direction opposite to the input gears. However in the case of invert gear selection, the rotation 
is usually 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 step when one wants to modify the gear will be the pressing of the clutch. Following this comes the neutral state of the vehicle to be performed. Proper optimization of the engine’s speed is necessary.
2. After the neutral equipment, one moves forward to the first equipment. The first equipment. This process is called double clutching. Inefficiency in executing the above measures 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 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 can 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 gear wheels stay intact. This is not the case for sliding mesh equipment box.
The other equipment boxes are noisy and create an undesired din.
Disadvantages:
It really is less efficient than 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 movements of the shaft.
Application:
A few of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and large machinery.
In this kind of gearbox, all the gears of the primary shaft are in continuous mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are given on the primary shaft i.electronic. one in between the clutch equipment and the second 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 the gears on the counter shaft are rigidly fixed with it.
As and when the left hand dog clutch is made to slide to the left by means of the apparatus shift lever, it meshes with the clutch equipment and the very best speed equipment is obtained. When the left hand dog clutch meshes with second gear, the second gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the initial speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all the gears are in constant mesh and hence because of this, they are safe from being damaged and irritating grinding sound does not happen while engaging and disengaging.