Constant Mesh Gear Box
Constant mesh gearbox can be a kind of Transmission in which all or most of the gears are always in mesh with each other, as opposed to a sliding-gear transmission, in which engagement is definitely obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are selected by small Clutches that connect the various gear sets to their construction and working of constant mesh gearbox shafts to ensure that power can be transmitted through them. The next diagram shows the arrangement of a continuous mesh gear box
Construction and operating of a continuous 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 really transmitting power. The gears in both shafts are usually meshed together.
To activate the gears with result shaft dog clutch is used. the dog clutch is certainly shifted by the seletor fork transferred by gear lever.To provide reverse gearing a idler equipment is used.
When the gear lever is pushed, the apparatus selector fork pushes your dog clutch. The dog clutch engages the gear and the result shaft, thus power from lay shaft right now transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is a type 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 pair of the meshed gears.
A constant mesh transmission typically includes 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 tranny was a great success in vehicles trade as presently there was a system 
which might offer needed torsion and velocity ratios wish by the automobile to face the street challenges however still there have been several vital issues with this gear that raised the question on its efficiency and responsibility. the problems 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 needed for driving 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 gear to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the velocity of the lay-shaft in order that the meshing of applicable gear will occur, save for he presses the clutch pedal and generate the apparatus lever to the desired equipment and unleash the clutch pedal and finally the desired gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a completely different speed compared to the meshing of those gears will 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 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 different types 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. As well dog clutches are given on the primary shaft: one between your clutch gear and the second gear; and the additional between your first gear and invert gear. The main shaft is manufactured splined and all of the gears are absolve to move on 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 to the left by using the gear shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the remaining dog clutch meshes with the second gear on the main shaft, the second speed equipment is achieved. Similarly, by sliding the right-hand dog clutch to the left and right, the first speed gear and reverse gear are obtained respectively In this kind of gearbox, because all the gears are in continuous mesh, they are secure from being broken and unpleasant grinding sound does not take place while engaging and disengaging them.
Continuous mesh gearbox is utilized for the smooth operating of a car. They are used to increase the rotating push (Torque); this is accompanied by a decrease in rate. It is a kind of manual transmission. The invention of earliest manual gear system can be traced back to the nineteenth century. There are multiple gear ratios present which provides various torque and swiftness 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 provided point of time.
In technical terms, it can be thought as a gearbox in which all of the gears are usually in a state of mesh. The gears stay fixed at their primary positions. The gears will stay engaged at all times. Learn more about its construction, working, advantages, drawbacks and applications in this article.
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 main shaft. Remember according to the equipment ratio, the swiftness of the counter shaft could be much less that the swiftness of the engine. The apparatus ratio can be defined as the ratio of one’s teeth of driven gear to the teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the automobile. The power is manufactured available to the primary shaft through the gears from the counter shaft. That is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is unique feature of constant mesh gearbox. It can be used for the coupling of any two shafts. That is completed by interference. Using 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 more than one, the primary shaft will work at a velocity that is slower compared to the counter shaft, and vice versa. The arrangement of both reverse, along with 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 among the result gears, namely initial, second, third and 4th. Gear ratios can be obtained for each of these. This can 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 then transmitted from the reverse gear to the invert idler. The idler wheel will change the direction of the rotation. In the case of forwarding direction gear selection, the result gears will rotate in a direction opposite to the input gears. But in the case of reverse equipment selection, the rotation can be in the same path as the input shaft.
The steps are taken up to change any gear in the continuous mesh gearbox system:
1. The first rung on the ladder when one wants to modify the gear will 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 forward to the first equipment. The first equipment. This process is known as double clutching. Inefficiency in executing the above steps might result in a severe and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the constant 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 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 gear wheels stay intact. This is simply not the case for sliding mesh gear box.
The other gear boxes are noisy and create an undesirable din.
Disadvantages:
It really is less efficient compared to the others because of higher mesh teeth. Skill is required for it.
The double clutch mesh is required. This is required to possess the spinning actions of the shaft.
Application:
A few of the vehicles which use this type of gearboxes are farm trucks, motorcycles, and heavy machinery.
In this type 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 provided on the main shaft i.electronic. one among the clutch gear and the second 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 is made to slide to the left by means of the gear shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the still 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 initial speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in constant mesh and hence for this reason, they are safe from being damaged and irritating grinding sound does not take place while engaging and disengaging.
