Constant Mesh Gear Box
Constant mesh gearbox is certainly a kind of Transmission in which all or the majority of the gears are always in mesh with each other, as opposed to 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 small Clutches that connect the many gear sets with their shafts so that power can be transmitted through them. The following diagram shows the set up of a continuous 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 transmitting power. The gears in both shafts are often meshed together.
To engage the gears with output shaft dog construction and working of constant mesh gearbox clutch can be used. the dog clutch is certainly shifted by the seletor fork moved by gear lever.To supply reverse gearing a idler equipment is used.
When the gear lever is pushed, the apparatus selector fork pushes the dog clutch. Your dog clutch engages the gear and the result shaft, therefore power from lay shaft at this point transmitted to result shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is that a type of manual transmission in which 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 helps in transmittal the required output to the most shaft by creating connection with the acceptable pair of the meshed gears.
A constant mesh transmission typically comes with 4 forward speeds and 1 reverse manual transmission configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmitting was a great success in cars trade as currently there is a system which might offer needed torsion and acceleration ratios desire by the vehicle to face the road challenges nevertheless still there were several vital issues with this equipment 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 traveling 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.electronic. once driver needs to shift the apparatus he preliminary presses the clutch pedal and generate the apparatus to the neutral, than once more he releases the clutch pedal and accelerate in order 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 produce the apparatus lever to the required gear and unleash the clutch pedal and finally 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 those gears will cause breakage to the gear teethes or continuous deterioration is there.
The shifting of gears could be 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. Too dog clutches are given on the main shaft: one between the clutch gear and the next gear; and the additional between your first gear and invert gear. The primary shaft is made 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 completely fixed with it.
When the left dog clutch is made to slide to the left by using the apparatus 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 next speed gear is achieved. Likewise, by sliding the right-hand dog clutch left and correct, the first speed gear and reverse gear are attained respectively In this kind of gearbox, because all the gears are in continuous mesh, they are secure from being damaged and unpleasant grinding sound does not occur while engaging and disengaging them.
Continuous mesh gearbox is utilized for the smooth functioning of an automobile. They are used to increase the rotating power (Torque); this is accompanied by a decrease in speed. It is a kind of manual transmitting. The invention of earliest manual gear system can be traced back to the nineteenth century. There are multiple equipment ratios present which gives various torque and swiftness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed lately contain all the gears mesh at any provided point of time.
In technical terms, it could be defined as a gearbox where all of the gears are generally in circumstances of mesh. The gears remain fixed at their first positions. The gears will remain engaged all the time. Find out more about its building, working, advantages, disadvantages 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 equipment ratio, the velocity of the counter shaft could be less that the rate of the engine. The apparatus ratio can be defined as the ratio of one’s teeth of driven gear to one’s 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. This is done relative to the gear ratio.
3. Dog clutch:
Dog clutch is unique feature of continuous mesh gearbox. It is used for the coupling of any two shafts. This is carried out by interference. Utilizing a dog clutch, numerous gears could be locked to the output 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 main shaft will continue to work at a velocity that is slower compared to the counter shaft, and vice versa. The arrangement 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 result gears, namely initial, second, third and 4th. Gear ratios can be obtained 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 road of the energy circulation completes. This happens because of the locking motion 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 invert gear to the invert idler. The idler wheel will change the direction of the rotation. Regarding forwarding direction gear selection, the result gears will rotate in a path opposite to the input gears. However in the case of invert gear selection, the rotation can be 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 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 vehicle to be performed. Proper optimization of the engine’s speed is required.
2. After the neutral gear, one moves ahead to the first equipment. The first gear. This process is called double clutching. Inefficiency in carrying out the above steps might result in a harsh and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the continuous gear mesh may be the usage of helical gears. The double helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are numerous conditions which might cause harm. Regarding constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. One’s teeth belonging to the gear wheels remain intact. This is not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an undesired din.
Disadvantages:
It really is less efficient than the others due to higher mesh teeth. Skill is necessary for it.
The double clutch mesh is required. This is necessary to possess the spinning movements of the shaft.
Application:
Some of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this kind 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 second gear, and the other between the first equipment and the reverse gear.
Your 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 hands dog clutch was created to slide to the left by means of the apparatus change lever, it meshes with the clutch equipment and the very best speed gear is obtained. When the left hands dog clutch meshes with second equipment, the second gear is obtained.
Similarly, by sliding correct 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 constant mesh and hence for this reason, they are safe from being damaged and irritating grinding sound will not occur while engaging and disengaging.