Constant Mesh Gear Box
Constant mesh gearbox is a kind of Transmission where all or most of the gears are always in mesh with each other, as opposed to a sliding-gear transmission, in which engagement is usually obtained by sliding some 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 with their shafts to ensure that power is transmitted through them. The next diagram shows the arrangement of a constant mesh gear box
Construction and working of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. The gears are rigidly fixed in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, thus not transmitting power. The gears in both shafts are constantly meshed together.
To activate the gears with output shaft dog clutch can be used. the dog clutch is certainly shifted by the seletor fork relocated by gear lever.To provide reverse gearing a idler equipment is used.
When the apparatus lever is pushed, the apparatus selector fork pushes your dog clutch. Your dog clutch engages the apparatus and the output shaft, therefore power from lay shaft now transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is a kind 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 devices named dog clutches square measure introduced which helps in transmittal the desired output to the the majority of shaft by creating connection with the acceptable pair of the meshed gears.
A continuous 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.electronic. sliding mesh transmitting was a great success in cars trade as presently there was a system which might provide needed torsion and rate ratios really want by the automobile to face the street challenges however still there were several vital problems with this equipment that raised the question on its effectiveness and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t an easy task because the shifting needed a special technique that wasn’t in any respect 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 since the name indicates that needed double engagement and disengagement of clutch for shifting one gear.
f i.e. once driver must shift the apparatus he initial presses the clutch pedal and produce the apparatus to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the acceleration of the lay-shaft in order that the meshing of relevant gear will occur, save for he presses the clutch pedal and produce the gear lever to the desired equipment 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 necessary as slippy and meshing of gears causes resistance to wear of shafts and gears.
Lay Shaft or counter Shaft.
There are various kinds of gears with both spur and helical gears like:
In Constant Mesh Gearbox gearbox, all gears of the primary 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 various other between the first gear and invert gear. The primary shaft is made splined and all the gears are absolve to move on it. Dog clutches can slide on the primary shaft and rotates with it. All the gears on the countershaft are completely fixed with it.
When the left dog clutch was created to slide to the left by making use of 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 gear is achieved. Likewise, by sliding the right-hand dog clutch to the left and correct, the first speed equipment and reverse gear are acquired 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 occur while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth functioning of a car. They are used to increase the rotating force (Torque); this is accompanied by a reduction in velocity. It is a kind of manual transmission. The invention of earliest manual gear system could be traced back to the nineteenth century. There are multiple gear ratios construction and working of constant mesh gearbox 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 specialized terms, it can be defined as a gearbox in which all the gears are always in a state of mesh. The gears stay fixed at their initial positions. The gears will remain engaged all the time. Find out more about its building, working, advantages, drawbacks and applications in this post.
It 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. Keeping in mind according to the gear ratio, the velocity of the counter shaft may be less that the rate of the engine. The gear ratio can be explained as the ratio of one’s teeth of driven equipment to one’s teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the automobile. The power is made available to the main shaft through the gears from the counter shaft. That 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 performed by interference. Utilizing a dog clutch, numerous gears can be locked to the output and input shafts.
The primary work of the gears may be the transmission of power between the shafts. If the gear ratio is more than one, the primary shaft will work at a speed that is slower than the counter shaft, and vice versa. The set up of both reverse, and also forward gears, is present.
Forward gear selection:
From the input shaft, the power starts flowing and is divided into four parts. Each component goes to one of the result gears, namely 1st, second, third and 4th. Gear ratios can be acquired for each of these. This is often done by the correct sliding of dog clutch over one’s teeth of the selected gearwheel. After this the road of the energy stream completes. This happens because of the locking motion of the output shaft.
Reverse gear selection:
The power will flow from the input shaft to the reverse gears. The energy is after that 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 path opposite to the insight gears. But in the case of invert equipment selection, the rotation is in the same path as the input shaft.
The steps are taken to change any gear in the constant mesh gearbox system:
1. The first step when one wants to change the gear would be the pressing of the clutch. After this comes the neutral state of the vehicle to be achieved. Proper optimization of the engine’s speed is necessary.
2. After the neutral gear, one moves ahead to the first equipment. The first gear. This process is known as double clutching. Inefficiency in carrying out the above guidelines might result in a severe and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
The first and foremost benefit of the continuous gear mesh is the utilization of helical gears. The double helical gears and the helical gears are really beneficial due to their quieter operating capabilities
There are many 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 tires stay intact. This is not the case for sliding mesh gear box.
The other equipment boxes are noisy and create an undesired din.
It really is less efficient than 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.
A few of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and large machinery.
In this kind of gearbox, all the gears of the main shaft are in constant mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are given on the main shaft i.e. one in between the clutch gear and the next gear, and the various other between the first gear 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 hand dog clutch was created to slide to the left by means of the gear change lever, it meshes with the clutch gear and the very best speed gear is obtained. When the 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 of the gears are in constant mesh and hence for this reason, they are safe from being damaged and irritating grinding sound will not happen while engaging and disengaging.
Constant Mesh Gear Box