Constant Mesh Gear Box
Constant mesh gearbox is certainly a type of Transmission where all or most of the gears are always in mesh with one another, instead of a sliding-gear transmission, where engagement is definitely 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 to their shafts to ensure that power is transmitted through them. The next diagram shows the set up of a continuous mesh gear box
Construction and working 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 result shaft rotates freely without engaging with shaft, hence not transmitting power. The gears in both shafts are always meshed together.
To engage the gears with result shaft dog clutch is used. the dog clutch is usually shifted by the seletor fork relocated by gear lever.To supply reverse gearing a idler gear is used.
When the gear lever is pushed, the apparatus selector fork pushes the dog clutch. Your dog clutch engages the apparatus and the output shaft, hence power from lay shaft right now transmitted to output 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 desired 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 might provide needed torsion and quickness ratios want by the automobile to face the road challenges nevertheless still there were several vital problems 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 whatsoever 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 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 again he releases the clutch pedal and accelerate in order to extend the swiftness of the lay-shaft in order that the meshing of relevant gear will occur, save for he presses the clutch pedal and produce the apparatus lever to the required 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 will cause breakage to the apparatus teethes or continuous deterioration 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 various kinds 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 primary shaft are in constantly meshed with the corresponding gears of the layshaft or countershaft. As well dog clutches are given on the main shaft: one between the clutch equipment and the next gear; and the various other between the first gear and invert gear. The main 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 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 next 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 obtained respectively In this kind of gearbox, because all the gears are in constant mesh, they are secure from being broken and unpleasant grinding audio does not take place 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 push (Torque); this is accompanied by a reduction in speed. It is a type of manual transmitting. The invention of earliest manual gear system could be traced back to the nineteenth century. There are multiple equipment ratios present which gives various torque and swiftness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed lately contain all of 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 initial positions. The gears will remain engaged all the time. Find out more about its construction, working, advantages, disadvantages and applications in this article.
Construction:
It 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 could be less that the swiftness of the engine. The apparatus ratio can be explained as the ratio of the teeth of driven equipment 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 unique feature of constant mesh gearbox. It is used for the coupling of any two shafts. That is carried out by interference. Using a dog clutch, different gears can be locked to the output and input shafts.
4. Gears:
The main 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 quickness that is slower compared to the counter shaft, and vice versa. The set up of both reverse, along with 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 among the output gears, namely first, second, third and 4th. Gear ratios can be obtained for each of these. This is often done by the correct sliding of dog clutch over one’s teeth of the chosen gearwheel. After this the path of the energy movement completes. This happens because of the locking motion of the result shaft.
Reverse gear selection:
The energy 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 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 reverse equipment selection, the rotation is in the same path as the insight shaft.
The steps are taken up 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. Following this comes the neutral condition of the vehicle to be achieved. Proper optimization of the engine’s speed is required.
2. After the neutral equipment, one moves forward to the first gear. The first gear. This process is called double clutching. Inefficiency in carrying out the above steps might result in a harsh and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh is 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 might cause harm. Regarding constant mesh gearbox, any damage is suffered entirely 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 double clutch mesh is necessary. This is necessary to have the spinning actions of the shaft.
Application:
Some 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 among the clutch equipment 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 fixed 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 gear is obtained. When the left hands dog clutch meshes with second equipment, 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 for this reason, they are secure from being damaged and irritating grinding sound will not take place while engaging and disengaging.
