construction and working of constant mesh gearbox

Constant Mesh Gear Box
Constant mesh gearbox can be a kind of Transmission where all or the majority of the gears are always in mesh with each other, instead of a sliding-gear transmission, in which engagement can be obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are selected by little Clutches that connect the many gear sets with their shafts to ensure that power is transmitted through them. The following diagram shows the arrangement of a constant mesh gear box
Construction and functioning of a continuous mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. 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 at all times meshed together.
To activate the gears with output shaft dog clutch can be used. the dog clutch is usually shifted by the seletor fork relocated by gear lever.To supply reverse gearing a idler construction and working of constant mesh gearbox equipment is used.
When the apparatus lever is pushed, the apparatus selector fork pushes the dog clutch. Your dog clutch engages the apparatus and the result shaft, thus power from lay shaft now transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is that a form 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 sq . measure introduced which helps in transmittal the desired output to the most shaft by creating connection with the acceptable couple of the meshed gears.
A constant mesh transmission typically comes with 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 an excellent success in vehicles trade as currently there was a system which might offer needed torsion and acceleration ratios wish by the automobile to face the street challenges nevertheless still there were several vital issues with this gear 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 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 since the name indicates that needed double engagement and disengagement of clutch for shifting 1 gear.
f i.e. once driver must shift the gear he preliminary presses the clutch pedal and generate the gear 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 generate the gear lever to the required gear and unleash the clutch pedal and at last the desired gear is obtained.
Since the gears are to be meshed square measure in continuous rotation with a totally different speed than the meshing of those gears may cause breakage to the gear teethes or continuous deterioration 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 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 primary shaft: one between your clutch gear and the second gear; and the various other between your first gear and invert gear. The main shaft is made splined and all the gears are free to move on it. Dog clutches can slide on the primary 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 help of the gear shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the left 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 to the left and right, the first speed gear and reverse gear are obtained respectively In this type of gearbox, because all of the gears are in constant mesh, they are safe from being damaged and unpleasant grinding sound does not happen while engaging and disengaging them.
Continuous mesh gearbox can be used for the smooth operating of a car. They are used to increase the rotating drive (Torque); this is accompanied by a reduction in velocity. It is a type of manual transmission. The invention of earliest manual gear system can be traced back again to the nineteenth century. There are multiple equipment ratios present which gives various torque and quickness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed recently contain all the gears mesh at any provided point of time.
In specialized terms, it could be defined as a gearbox in which all of the gears are at all times in circumstances of mesh. The gears stay fixed at their original positions. The gears will remain engaged all the time. Find out more about its building, working, advantages, drawbacks and applications in this article.
Construction:
It really is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct contact with the clutch and the main shaft. Remember according to the gear ratio, the speed of the counter shaft may be less that the acceleration 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 relative to the gear ratio.
3. Dog clutch:
Dog clutch is particular feature of continuous mesh gearbox. It is utilized for the coupling of any two shafts. This is done by interference. Utilizing a dog clutch, various gears can be locked to the result 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 primary shaft will continue to work at a rate that is slower compared to 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 part goes to one of the output gears, namely 1st, second, third and fourth. Gear ratios can be obtained for each of them. This is often done by the proper sliding of dog clutch over one’s 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 after that transmitted from the invert gear to the invert idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction gear selection, the output gears will rotate in a direction opposite to the insight gears. However in the case of invert equipment selection, the rotation is in the same direction as the input shaft.
The steps are taken to change any gear in the continuous mesh gearbox system:
1. The first rung on the ladder when one wants to change the gear will be the pressing of the clutch. After this comes the neutral state of the automobile to be performed. Proper optimization of the engine’s speed is necessary.
2. After the neutral gear, one moves forwards to the first gear. The first gear. This process is called double clutching. Inefficiency in executing the above measures might result in a harsh and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
Advantages:
The first and foremost advantage of the constant gear mesh is the utilization of helical gears. The dual helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are various conditions which might cause harm. Regarding continuous mesh gearbox, any harm is suffered entirely by the dog clutch teeth. One’s teeth belonging to the apparatus wheels remain 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 is less efficient compared to the others due to higher mesh teeth. Skill is required for it.
The double clutch mesh is required. This is necessary to possess the spinning actions of the shaft.
Application:
A few of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and heavy machinery.
In this type 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 primary shaft i.e. one among the clutch gear and the second 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 fixed with it.
As so when the left hands dog clutch is made to slide to the left by means of the apparatus shift lever, it meshes with the clutch equipment and the top speed equipment is obtained. When the still left hand dog clutch meshes with second equipment, the second gear is obtained.
Similarly, by sliding right hand dog clutch to the left and right, the first speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all the gears are in constant mesh and hence because of this, they are safe from being damaged and irritating grinding sound will not take place while engaging and disengaging.