construction and working of constant mesh gearbox

Constant Mesh Gear Box
Constant mesh gearbox is usually a type of Transmission in which all or most of the gears are always in mesh with each other, instead of 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 selected by small Clutches that connect the various gear sets to their shafts to ensure that power is certainly transmitted through them. The next diagram shows the set up of a constant mesh gear box
Construction and working of a continuous mesh gear box
Constant gear mesh gearbox employed helical gears for power transmission. 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 at all times meshed together.
To activate the gears with output shaft dog clutch can be used. the dog clutch can be shifted by the seletor fork relocated 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. The dog clutch engages the gear and the result shaft, thus power from lay shaft today transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous 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 products named dog clutches sq . measure introduced which assists in transmittal the required output to the most shaft by creating contact with the acceptable couple of the meshed gears.
A continuous mesh transmission typically comes with 4 forward speeds and 1 reverse manual tranny configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmitting was an excellent success in cars trade as currently there was a system which might offer needed torsion and velocity ratios desire by the automobile to face the road challenges however still there were several vital issues with this gear that raised the question on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t an easy task since the shifting needed a special construction and working of constant mesh gearbox technique that wasn’t in any respect everybody’s cup of tea, a talented driver was necessary 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 a single gear.
f i.e. once driver needs to shift the gear he initial 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 speed of the lay-shaft to ensure that the meshing of applicable gear will happen, save for he presses the clutch pedal and create the gear lever to the desired gear and unleash the clutch pedal and finally the required gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a totally different speed compared to the meshing of those gears may cause breakage to the gear 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 primary 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 second gear; and the additional between the first gear and invert gear. The primary shaft is manufactured splined and all of the gears are absolve to move on it. Dog clutches can slide on the main shaft and rotates with it. All the gears on the countershaft are permanently fixed with it.
When the left dog clutch was created to slide to the left with the aid of the apparatus shift lever, it meshes with the clutch gear and the very best speed gear is obtained. When the remaining dog clutch meshes with the second gear on the primary shaft, the second speed equipment is achieved. Likewise, by sliding the right-hand dog clutch left and correct, the first speed equipment and reverse equipment are attained respectively In this type of gearbox, because all of the gears are in continuous mesh, they are safe from being damaged and unpleasant grinding audio does not occur while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth working of a car. They are used to increase the rotating push (Torque); that is accompanied by a decrease in swiftness. It is a kind of manual transmitting. The invention of earliest manual equipment system can be traced back again to the nineteenth century. There are multiple gear ratios present which provides various torque and velocity ratio. Along with this, the reverse mechanism can be present. This manual transmissions which are developed lately contain all the gears mesh at any given point of time.
In technical terms, it could be thought as a gearbox in which all the gears are generally 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 structure, working, advantages, drawbacks 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. Remember according to the equipment ratio, the quickness of the counter shaft could be less that the quickness of the engine. The gear ratio can be explained as the ratio of the teeth of driven gear to one's teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the vehicle. The power is manufactured available to the primary shaft through the gears from the counter shaft. This is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is particular feature of constant mesh gearbox. It can be used for the coupling of any two shafts. That is done by interference. Using a dog clutch, numerous gears can be locked to the result and input shafts.
4. Gears:
The primary work of the gears may be the transmission of power between your shafts. If the gear ratio is several, the main shaft will continue to work at a velocity that is slower than the counter shaft, and vice versa. The set up of both reverse, as well as forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is divided into four parts. Each component goes to among the output gears, namely 1st, second, third and fourth. Gear ratios can be obtained 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 path of the energy movement 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 power is then transmitted from the reverse gear to the invert idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction equipment selection, the result gears will rotate in a direction opposite to the input gears. But in the case of reverse equipment selection, the rotation is certainly in the same path as the insight shaft.
The steps are taken to change any gear in the constant mesh gearbox system:
1. The first rung on the ladder when one wants to modify the gear would be the pressing of the clutch. After this comes the neutral state of the vehicle to be performed. 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 called double clutching. Inefficiency in executing the above steps might result in a harsh and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the constant gear mesh may be the utilization of helical gears. The dual helical gears and the helical gears are really beneficial due to their quieter operating capabilities
There are many conditions which might cause harm. In the case of continuous mesh gearbox, any damage is suffered completely by the dog clutch teeth. The teeth belonging to the apparatus tires remain intact. This is simply not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an undesired din.
Disadvantages:
It is less efficient than the others due to higher mesh teeth. Skill is required for it.
The double clutch mesh is required. This is required to have the spinning actions of the shaft.
Application:
Some of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this type of gearbox, all 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 given on the primary shaft i.e. one in between the clutch equipment and the second gear, and the other between the first equipment and the reverse equipment.
The dog clutch can slide on the shaft and rotate with it. While, all the gears on the counter shaft are rigidly fixed with it.
As and when the left hands dog clutch was created to slide to the left by means of the apparatus shift lever, it meshes with the clutch equipment and the top speed gear is obtained. When the remaining hand dog clutch meshes with second gear, the second gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the initial speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all of the gears are in constant mesh and hence because of this, they are safe from being damaged and irritating grinding sound does not happen while engaging and disengaging.