Constant Mesh Gear Box
Constant mesh gearbox is a type 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 definitely obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are chosen by small Clutches that connect the various gear sets with their shafts to ensure that power can be transmitted through them. The following diagram shows the set up of a constant mesh gear box
Construction and functioning of a constant 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 result shaft rotates freely without engaging with shaft, therefore not transmitting power. The gears in both shafts are usually meshed together.
To engage the gears with output shaft dog clutch is 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 gear selector fork pushes the dog clutch. The dog clutch engages the apparatus and the output shaft, hence power from lay shaft today transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is a type of manual transmission in which sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears as well as the new shifting gadgets named dog clutches square measure introduced which helps in transmittal the desired output to the many shaft by creating contact 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 transmission was a great success in cars trade as currently there was a system which can provide needed torsion and quickness ratios need by the automobile to face the street challenges nevertheless still there have been several vital issues with this gear that raised the issue on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t a simple task because the shifting needed a particular technique that wasn’t in any respect 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 one particular gear.
f i.e. once driver must shift the apparatus he preliminary presses the clutch pedal and generate the gear to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the speed of the lay-shaft in order that the meshing of applicable gear will happen, save for he presses the clutch pedal and create the apparatus lever to the required equipment and unleash the clutch pedal and at last the desired gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a completely different speed compared to the meshing of these gears will cause breakage to the apparatus 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 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. As well dog clutches are provided on the main shaft: one between your clutch gear and the next gear; and the additional between the first gear and invert gear. The main shaft is manufactured splined and all of the gears are absolve to move onto it. Dog clutches can slide on the main shaft and rotates with it. All of the gears on the countershaft are permanently fixed with it.
When the left dog clutch is made to slide left with the help 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 next speed gear is achieved. Similarly, by sliding the right-hand dog clutch to the left and correct, the first speed gear and reverse gear are acquired respectively In this type of gearbox, because all of the gears are in continuous mesh, they are secure from being broken 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 accustomed to increase the rotating drive (Torque); that is accompanied by a decrease in swiftness. It is a type of manual tranny. The invention of earliest manual gear system can be traced back again to the nineteenth century. There are multiple equipment ratios present which provides various torque and swiftness ratio. Additionally, the reverse mechanism is also present. This manual transmissions which are developed recently contain all of the gears mesh at any given point of time.
In specialized terms, it could be defined as a gearbox in which all the gears are at all times in a state of mesh. The gears stay fixed at their unique positions. The gears will stay engaged at all times. Find out more about its structure, 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. Keeping in mind according to the gear ratio, the rate of the counter shaft could be less that the velocity of the engine. The gear ratio can be defined as the ratio of one’s teeth of driven equipment to the teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the vehicle. The power is made available to the primary shaft through the gears from the counter shaft. That is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is special feature of constant mesh gearbox. It is used for the coupling of any two shafts. That is done by interference. Utilizing a dog clutch, different gears can be locked to the output and input shafts.
4. Gears:
The primary work of the gears may be the transmission of power between the shafts. If the apparatus ratio is more than one, the primary shaft will work at a quickness that is slower compared to the counter shaft, and vice versa. The arrangement of both reverse, as well as forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is construction and working of constant mesh gearbox divided into four parts. Each component goes to one of the output gears, namely first, second, third and fourth. 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 circulation completes. This happens because of the locking movement of the output shaft.
Reverse gear selection:
The power will flow from the input shaft to the reverse gears. The power is after that transmitted from the reverse gear to the reverse idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction equipment selection, the result gears will rotate in a path opposite to the input gears. But in the case of invert equipment selection, the rotation can be in the same direction as the insight shaft.
The steps are taken to change any gear in the continuous mesh gearbox system:
1. The first step when one wants to change the gear would be the pressing of the clutch. Following this comes the neutral state of the vehicle to be achieved. Proper optimization of the engine’s speed is required.
2. After the neutral gear, one moves forward to the first equipment. The first gear. This process is called double clutching. Inefficiency in executing the above actions might lead to a harsh and gnashing sound.
Advantages and Disadvantages of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh may be the utilization of helical gears. The double helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are various conditions which can cause harm. Regarding constant mesh gearbox, any harm is suffered entirely by your dog clutch teeth. The 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 unwanted din.
Disadvantages:
It really is less efficient than the others due to higher mesh teeth. Skill is required for it.
The dual clutch mesh is necessary. This is necessary to have the spinning actions of the shaft.
Application:
A few of the vehicles designed to use this type of gearboxes are farm trucks, motorcycles, and heavy machinery.
In this type of gearbox, all of 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 provided on the main shaft i.electronic. one in between the clutch gear and the next gear, and the other between the first gear and the reverse equipment.
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 so when the left hands dog clutch is made to slide to the left by means of the gear shift lever, it meshes with the clutch gear and the top speed equipment is obtained. When the remaining hands dog clutch meshes with second equipment, the next gear is obtained.
Similarly, by sliding right hand dog clutch to the left and right, the initial speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in continuous mesh and hence for this reason, they are secure from being damaged and irritating grinding sound will not occur while engaging and disengaging.