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 a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are selected by little Clutches that connect the various gear sets to their shafts so that power is definitely transmitted through them. The next diagram shows the arrangement of a continuous mesh gear box
Construction and functioning 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, therefore not transmitting power. The gears in both shafts are constantly meshed together.
To activate the gears with result 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 equipment is used.
When the gear lever is pushed, the apparatus selector fork pushes the dog clutch. The dog clutch engages the apparatus and the result shaft, therefore power from lay shaft now transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is that a form 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 gadgets named dog clutches square measure introduced which helps in transmittal the required output to the most shaft by creating contact with the acceptable pair of the meshed gears.
A continuous mesh transmission typically comes with 4 forward speeds and 1 reverse manual transmission configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmission was an excellent success in cars trade as currently there was a system which might provide needed torsion and velocity ratios want by the automobile to face the street challenges however still there were several vital problems with this gear that raised the issue on its effectiveness and responsibility. the problems 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 one gear.
f i.electronic. once driver must shift the apparatus he preliminary presses the clutch pedal and generate the gear to the neutral, than once again he releases the clutch pedal and accelerate in order to extend the quickness of the lay-shaft in order that the meshing of relevant gear will happen, save for he presses the clutch pedal and generate the gear lever to the required 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 completely different speed than 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 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 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 your clutch gear and the next gear; and the additional between the first gear and reverse gear. The primary shaft is made 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 top speed gear is obtained. When the left dog clutch meshes with the second gear on the main shaft, the second speed equipment is achieved. Similarly, by sliding the right-hand dog clutch to the left and right, the first speed equipment and reverse equipment are obtained respectively In this kind 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 functioning of an automobile. They are used to increase the rotating drive (Torque); that is accompanied by a decrease in quickness. It is a type of manual transmission. The invention of earliest manual equipment system could be traced back again to the nineteenth century. There are multiple equipment ratios present which gives various torque and swiftness ratio. Along with this, the reverse mechanism is also 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 where all of the gears are always in a state of mesh. The gears remain fixed at their primary positions. The gears will stay engaged all the time. Learn more about its building, working, advantages, drawbacks and applications in this post.
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. Keeping in mind according to the equipment ratio, the quickness of the counter shaft may be much less that the speed of the engine. The apparatus ratio can be defined as the ratio of one’s teeth of driven gear 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 primary shaft through the gears from the counter shaft. This is done relative to 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. This is completed 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 may be the transmission of power between the shafts. If the gear ratio is several, the primary shaft will work at a rate that is slower than the counter shaft, and vice versa. The set up of both reverse, in addition to forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is split into four parts. Each component goes to among the result gears, namely first, second, third and 4th. Gear ratios can be acquired for each of these. This could be 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 due to the locking motion of the result 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 equipment selection, the output gears will rotate in a direction opposite to the insight gears. But in the case of reverse gear selection, the rotation is definitely in the same path as the input shaft.
The steps are taken up to change any gear in the continuous 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 achieved. Proper construction and working of constant mesh gearbox optimization of the engine’s speed is necessary.
2. After the neutral equipment, one moves forwards to the first gear. The first gear. This process is called double clutching. Inefficiency in carrying out the above actions might result in a harsh and gnashing sound.
Advantages and Disadvantages of Continuous Mesh Gearbox:
Advantages:
The first and foremost advantage of the continuous gear mesh is the utilization of helical gears. The double helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are many conditions which can cause harm. Regarding constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. The teeth belonging to the gear tires remain intact. This is not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an unwanted din.
Disadvantages:
It is less efficient than the others due to higher mesh teeth. Skill is required for it.
The double clutch mesh is necessary. This is required to have the spinning actions of the shaft.
Application:
A few of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and large machinery.
In this type of gearbox, all of the gears of the main shaft are in continuous 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 second gear, and the other between the first equipment and the reverse gear.
Your 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 left by means of the apparatus change lever, it meshes with the clutch gear and the very best speed equipment is obtained. When the still left hand dog clutch meshes with second equipment, the next gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the first speed gear and reverse gear are obtained respectively.
In this type of gearbox, all the gears are in constant mesh and hence because of this, they are safe from being damaged and irritating grinding sound does not occur while engaging and disengaging.