Constant Mesh Gear Box
Constant mesh gearbox is a kind of Transmission where all or most of the gears are always in mesh with one another, instead of a sliding-gear transmission, where 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 small Clutches that connect the various gear sets with their shafts so that power is usually transmitted through them. The next diagram shows the arrangement of a constant mesh gear box
Construction and operating of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power transmission. The gears are rigidly set in the lay shaft. The gears in output shaft rotates freely without engaging with shaft, hence not really 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 shifted by the seletor fork relocated by gear lever.To supply reverse gearing a idler gear is used.
When the gear lever is construction and working of constant mesh gearbox pushed, the gear selector fork pushes your dog clutch. Your dog clutch engages the apparatus and the output shaft, hence power from lay shaft right now transmitted to result shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is 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 products named dog clutches square measure introduced which assists in transmittal the required output to the many shaft by creating connection 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.electronic. sliding mesh transmitting was an excellent success in cars trade as presently there is a system which can provide needed torsion and speed ratios want by the automobile to face the street challenges nevertheless still there were several vital issues 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 because the name indicates that needed dual engagement and disengagement of clutch for shifting 1 gear.
f i.e. once driver must shift the apparatus 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 quickness of the lay-shaft to ensure that the meshing of relevant gear will occur, save for he presses the clutch pedal and produce the apparatus lever to the desired gear and unleash the clutch pedal and finally the desired gear is obtained.
Since the gears should be meshed square measure in continuous rotation with a completely different speed than the meshing of these gears may cause breakage to the apparatus teethes or continuous wear and tear is there.
The shifting of gears is actually 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 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 provided on the main shaft: one between the clutch equipment and the second gear; and the other between the first gear and reverse gear. The main shaft is manufactured splined and all the gears are absolve to move onto 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 left by making use 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 gear is achieved. Similarly, by sliding the right-hand dog clutch left and correct, the first speed equipment and reverse equipment are obtained respectively In this type of gearbox, because all the gears are in constant mesh, they are secure from being broken and unpleasant grinding sound does not take place while engaging and disengaging them.
Continuous mesh gearbox is used for the smooth working of a car. They are accustomed to increase the rotating power (Torque); this is accompanied by a decrease in rate. It is a type of manual transmitting. The invention of earliest manual gear system could be traced back again to the nineteenth century. There are multiple equipment ratios present which provides various torque and acceleration ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed recently contain all the gears mesh at any given point of time.
In specialized terms, it can be defined as a gearbox in which all the gears are generally in circumstances of mesh. The gears remain fixed at their original positions. The gears will remain engaged all the time. Find out more about its construction, working, advantages, disadvantages and applications in this post.
Construction:
It is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct connection 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 apparatus ratio can be explained as the ratio of one’s teeth of driven equipment to one’s teeth of the driver gear.
2. Main shaft:
This shaft operates the speed of the vehicle. 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 unique feature of constant mesh gearbox. It is used for the coupling of any two shafts. This is carried out by interference. Utilizing a dog clutch, various gears can be locked to the output and input shafts.
4. Gears:
The primary work of the gears is 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, along with forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is split into four parts. Each part goes to one of the output gears, namely first, second, third and 4th. 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 path of the energy circulation completes. This happens due to 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 reverse idler. The idler wheel changes the path of the rotation. Regarding forwarding direction gear selection, the output gears will rotate in a direction opposite to the input gears. But in the case of invert gear selection, the rotation is usually 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 modify the gear will be the pressing of the clutch. After this comes the neutral condition of the automobile to be achieved. Proper optimization of the engine’s speed is required.
2. After the neutral gear, one moves forward to the first gear. The first gear. This process is called double clutching. Inefficiency in performing the above steps might lead to a severe and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh is the usage 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 might cause harm. In the case of constant mesh gearbox, any damage is suffered completely by your dog clutch teeth. One’s teeth belonging to the apparatus tires remain intact. This is not the case for sliding mesh equipment box.
The other equipment boxes are noisy and create an undesired din.
Disadvantages:
It is less efficient than the others because of higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is necessary. This is required to have the spinning actions of the shaft.
Application:
A few of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and weighty 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 additional between the first equipment 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 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 gear, the second gear is obtained.
Similarly, by sliding correct hand dog clutch to the left and right, the 1st speed gear and reverse gear are obtained respectively.
In this type of gearbox, all the gears are in continuous mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not take place while engaging and disengaging.