Constant Mesh Gear Box
Constant mesh gearbox can be a kind of Transmission where all or the majority of the gears are always in mesh with one another, as opposed to a sliding-gear transmission, in which engagement can be obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are chosen by little Clutches that connect the various gear sets to their shafts so that power is certainly transmitted through them. The following diagram shows the arrangement of a constant mesh gear box
Construction and operating of a continuous mesh gear box
Constant gear mesh gearbox employed helical gears for power transmitting. The gears are rigidly fixed in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, hence not really transmitting power. The gears in both shafts are constantly meshed together.
To activate the gears with result shaft dog clutch is used. the dog clutch can be shifted by the seletor fork transferred by gear lever.To supply invert gearing a idler gear is used.
When the gear lever is pushed, the apparatus selector fork pushes the dog clutch. The dog clutch engages the apparatus and the output shaft, therefore power from lay shaft right now transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous 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 as well as 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 pair of the meshed gears.
A constant mesh transmission typically includes 4 forward speeds and 1 reverse manual transmission configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh tranny was an excellent success in vehicles trade as currently there is a system which might offer needed torsion and velocity ratios want by the automobile to face the street challenges nevertheless still there were several vital problems with this equipment that raised the query on its performance and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t a simple 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 because the name indicates that needed dual engagement and disengagement of clutch for shifting 1 gear.
f i.e. once driver must shift the apparatus he initial presses the clutch pedal and generate 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 happen, save for he presses the clutch pedal and generate the gear lever to the desired equipment and unleash the clutch pedal and finally the required gear is obtained.
Since the gears construction and working of constant mesh gearbox should be meshed square measure in continuous rotation with a totally different speed than the meshing of these gears may cause breakage to the apparatus 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 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 the clutch gear and the second gear; and the additional between your first gear and invert gear. The main shaft is made splined and all of the gears are free to move on it. Dog clutches can slide on the primary shaft and rotates with it. All the gears on the countershaft are permanently fixed with it.
When the left dog clutch is made 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 still left dog clutch meshes with the next gear on the primary shaft, the next speed equipment is achieved. Similarly, by sliding the right-hand dog clutch to the left and right, the first speed gear and reverse equipment are attained respectively In this kind of gearbox, because all the gears are in constant mesh, they are safe from being damaged and unpleasant grinding sound does not occur while engaging and disengaging them.
Constant mesh gearbox is used for the smooth functioning of an automobile. They are accustomed to increase the rotating power (Torque); this is accompanied by a reduction in acceleration. It is a type of manual tranny. The invention of earliest manual gear system could be traced back again to the nineteenth century. There are multiple gear ratios present which gives various torque and velocity ratio. Along with this, the reverse mechanism is also 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 the gears are usually in a state of mesh. The gears stay fixed at their first positions. The gears will remain engaged at all times. Find out more about its building, working, advantages, disadvantages 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. Keeping in mind according to the gear ratio, the velocity of the counter shaft may be less that the speed of the engine. The gear ratio can be explained as the ratio of the teeth of driven gear to the teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the vehicle. The power is made 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 constant mesh gearbox. It is used for the coupling of any two shafts. That is carried out by interference. Using a dog clutch, numerous gears could be locked to the output 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 primary shaft will continue to work at a quickness that is slower than the counter shaft, and vice versa. The set up of both reverse, and also 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 these. This could be done by the proper sliding of dog clutch over the teeth of the selected gearwheel. After this the road of the energy stream completes. This happens due to the locking movement of the output 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 reverse idler. The idler wheel will change the direction of the rotation. Regarding forwarding direction equipment selection, the result gears will rotate in a path opposite to the insight gears. But in the case of reverse gear selection, the rotation is certainly in the same direction as the input shaft.
The steps are taken to change any gear in the continuous mesh gearbox system:
1. The first rung on the ladder when one wants to change the gear would be the pressing of the clutch. After this comes the neutral condition 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 called dual clutching. Inefficiency in carrying out the above steps might result in a harsh and gnashing sound.
Advantages and Disadvantages of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh is the utilization of helical gears. The dual helical gears and the helical gears are really beneficial due to their quieter operating capabilities
There are numerous conditions which can cause harm. Regarding constant mesh gearbox, any damage is suffered entirely by the dog clutch teeth. The teeth belonging to the gear wheels stay intact. This is not the case for sliding mesh gear box.
The other gear boxes are noisy and create an undesirable din.
Disadvantages:
It is less efficient compared to the others due to higher mesh teeth. Skill is necessary for it.
The double clutch mesh is required. This is required to have 
the spinning actions 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 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.electronic. one among the clutch equipment and the next gear, and the other between the first equipment and the reverse gear.
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 hands 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 still left hand dog clutch meshes with second gear, the next gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the 1st speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all the gears are in continuous mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not occur while engaging and disengaging.
