Constant Mesh Gear Box
Constant mesh gearbox is certainly a type of Transmission where all or the majority of the gears are always in mesh with one another, as opposed to a sliding-gear transmission, in which 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 construction and working of constant mesh gearbox usually transmitted through them. The next diagram shows the set up of a constant mesh gear box
Construction and functioning of a constant mesh gear box
Constant equipment 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, therefore 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 shifted by gear lever.To supply reverse gearing a idler equipment is used.
When the apparatus lever is pushed, the gear selector fork pushes your dog clutch. Your dog clutch engages the gear and the output shaft, hence power from lay shaft now transmitted to result 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 products named dog clutches square measure introduced which helps in transmittal the required output to the most shaft by creating connection with the acceptable pair of the meshed gears.
A continuous 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 an excellent success in cars trade as presently there is a system which might offer needed torsion and velocity ratios desire by the automobile to face the street challenges however still there have been several vital issues with this gear that raised the query on its efficiency and responsibility. the problems long-faced were as follows-
The shifting of gears wasn’t a simple 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 generating 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.electronic. once driver must shift the gear he initial presses the clutch pedal and produce the apparatus to the neutral, than once more he releases the clutch pedal and accelerate in order to extend the acceleration of the lay-shaft to ensure that the meshing of applicable gear will take place, save for he presses the clutch pedal and create 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 compared to the meshing of those 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 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. Too dog clutches are provided on the primary shaft: one between the clutch gear and the next gear; and the additional between your first gear and invert gear. The primary shaft is manufactured splined and all the gears are free to move onto it. Dog clutches can slide on the primary shaft and rotates with it. All of the gears on the countershaft are permanently fixed with it.
When the left dog clutch was created to slide to the left by making use of the gear shift lever, it meshes with the clutch gear and the very best speed gear is obtained. When the still left 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 to the left and right, the first speed gear and reverse gear are obtained respectively In this kind of gearbox, because all the gears are in continuous mesh, they are safe from being damaged and unpleasant grinding sound does not occur while engaging and disengaging them.
Continuous mesh gearbox is used for the smooth functioning of a car. They are used to increase the rotating pressure (Torque); that is accompanied by a reduction in velocity. It is a kind of manual transmitting. The invention of earliest manual gear system can be traced back to the nineteenth century. There are multiple equipment ratios present which provides various torque and quickness ratio. Along with this, the reverse mechanism is also present. This manual transmissions which are developed recently contain all the gears mesh at any given point of time.
In technical terms, it could be defined as a gearbox in which all the gears are often in circumstances of mesh. The gears remain fixed at their unique positions. The gears will stay engaged at all times. Find out more about its construction, working, advantages, disadvantages 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 contact with the clutch and the main shaft. Keeping in mind according to the equipment ratio, the speed of the counter shaft may be much less that the velocity of the engine. The gear ratio can be explained as the ratio of one’s 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 main shaft through the gears from the counter shaft. This is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is special feature of constant mesh gearbox. It is utilized for the coupling of any two shafts. That 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 your shafts. If the apparatus ratio is several, the primary shaft will continue to work at a speed that is slower than the counter shaft, and vice versa. The set up of both reverse, and also forward gears, is present.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is divided into four parts. Each part goes to among the output gears, namely initial, second, third and fourth. 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 road of the energy circulation completes. This happens because of the locking movement of the output shaft.
Reverse gear selection:
The energy will flow from the input shaft to the reverse gears. The power is after that transmitted from the invert gear to the reverse idler. The idler wheel will change the direction 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 usually in the same path as the insight shaft.
The steps are taken to change any gear in the continuous mesh gearbox system:
1. The first step when one really wants to change the gear will be the pressing of the clutch. After this comes the neutral condition 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 equipment. This process is called double clutching. Inefficiency in executing the above techniques might lead to a severe and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost benefit of the continuous gear mesh is the usage of helical gears. The dual helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are numerous conditions which might cause harm. In the case of constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. One’s teeth belonging to the gear tires 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 is less efficient than the others because of higher mesh teeth. Skill is necessary for it.
The double clutch mesh is required. This is required to possess the spinning actions of the shaft.
Application:
A few of the vehicles which 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 continuous mesh with the corresponding gears of the counter shaft or lay shaft.
Two dog clutches are provided on the main shaft i.e. one in between the clutch gear and the next gear, and the various other between the first gear 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 fixed with it.
As and when the left hand dog clutch was created to slide to the left by means of the apparatus change lever, it meshes with the clutch equipment and the top speed equipment is obtained. When the remaining 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 of the gears are in constant mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not take place while engaging and disengaging.
