Constant Mesh Gear Box
Constant mesh gearbox is definitely a kind of Transmission where all or most of the gears are always in mesh with one another, instead of a sliding-gear transmission, in which engagement is usually obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are selected by little Clutches that connect the various gear sets with their shafts so that power is definitely 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 equipment 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, thus 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 moved 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 gear and the output shaft, hence power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is that a type of manual transmission where sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears as well as the new shifting products named dog clutches sq . measure introduced which assists in transmittal the required output to the many shaft by creating contact with the acceptable couple of the meshed gears.
A constant mesh transmission typically includes 4 forward speeds and 1 reverse manual tranny configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmitting was an excellent success in vehicles trade as presently there was a system which might provide needed torsion and speed ratios desire by the automobile to face the road challenges however still there have been several vital issues with this gear that raised the issue on its performance and responsibility. the problems long-faced were as follows-
The shifting of gears wasn’t a simple task since the shifting needed a special 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 double engagement and disengagement of clutch for shifting 1 gear.
f i.e. once driver needs to shift the apparatus he preliminary presses the clutch pedal and produce the gear to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the quickness of the lay-shaft to ensure that the meshing of applicable gear will happen, save for he presses the clutch pedal and produce the gear lever to the required 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 than the meshing of those 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 given on the main shaft: one between your clutch equipment and the next gear; and the other between your first gear and reverse gear. The main 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 is made to slide left by making use 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 next gear on the main shaft, the second speed gear is achieved. Similarly, by sliding the right-hand dog clutch left and right, the first speed gear and reverse equipment are acquired respectively In this kind of gearbox, because all of the gears are in continuous mesh, they are secure from being damaged and unpleasant grinding sound does not happen while engaging and disengaging them.
Continuous mesh gearbox can be used for the smooth working of a car. They are used to increase the rotating power (Torque); this is accompanied by a decrease in quickness. It is a type of manual transmitting. 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 speed ratio. Along with this, the reverse mechanism is also present. This manual transmissions which are developed lately contain all the gears mesh at any provided point of time.
In technical terms, it can be defined as a gearbox in which all of the gears are usually in circumstances of mesh. The gears stay fixed at their unique 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 following 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 equipment ratio, the speed of the counter shaft may be less that the rate of the engine. The gear 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 main shaft through the gears from the counter shaft. This is done relative to the gear ratio.
3. Dog clutch:
Dog clutch is special feature of continuous mesh gearbox. It is used for the coupling of any two shafts. This is completed by interference. Utilizing a dog clutch, different gears can be locked to the output and input shafts.
4. Gears:
The main work of the gears may be the transmission of power between the shafts. If the gear ratio is several, the main shaft will work at a quickness that is slower than the counter shaft, and vice versa. The set up of both reverse, along with forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is divided into four parts. Each part goes to one of the output gears, namely first, second, third and fourth. Gear ratios can be acquired for each of these. This could be done by the correct sliding of dog clutch over the teeth of the selected gearwheel. After this the path of the energy stream completes. This happens because of the locking motion 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 reverse gear to the reverse idler. The idler wheel changes the direction of the rotation. In the case of forwarding direction equipment selection, the output gears will rotate in a direction opposite to the insight gears. But in the case of invert gear selection, the rotation is definitely 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 really wants to modify the gear will be the pressing of the clutch. After 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 forward to the first equipment. The first gear. This process is called dual clutching. Inefficiency in performing the above steps might result in a harsh and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh may be the utilization of helical gears. The dual helical gears and the helical gears are extremely beneficial due to their quieter operating capabilities
There are numerous conditions which can cause harm. In the case of continuous mesh gearbox, any damage is suffered completely by your dog clutch teeth. The teeth belonging to the apparatus wheels stay intact. This is simply not the case for sliding mesh gear 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 required for it.
The double clutch mesh is necessary. This is required to possess the spinning motions of the shaft.
Application:
Some of the vehicles which 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 continuous mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are provided on the primary shaft i.e. one among the clutch gear and the next gear, and the additional between the first gear and the reverse gear.
The dog clutch can slide on the shaft and rotate with it. While, all the gears on the counter shaft are rigidly set with it.
As so when the left hand dog clutch is made to slide to the left by means of the gear change lever, it meshes with the clutch equipment and the top speed gear is obtained. When the left hand dog clutch meshes with second equipment, the next gear is obtained.
Similarly, by sliding correct hand dog clutch 
to the left and right, the first speed gear and reverse gear are obtained respectively.
In this type of gearbox, all the gears are in constant mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not happen while engaging and disengaging.
Call us to be in the understand concerning construction and working of constant mesh gearbox.