construction and working of constant mesh gearbox

Constant Mesh Gear Box
Constant mesh gearbox is a type of Transmission in which all or the majority of the gears are always in mesh with each other, instead of a sliding-gear transmission, where engagement is obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Gear ratios are chosen by little Clutches that connect the many gear sets to their shafts to ensure that power can be transmitted through them. The next diagram shows the set up of a continuous 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 output shaft rotates freely without engaging with shaft, hence not transmitting power. The gears in both shafts are generally meshed together.
To engage the gears with result shaft dog clutch is used. the dog clutch is definitely shifted by the seletor fork transferred 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 gear and the output shaft, therefore power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is that a kind of manual transmission where sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears and also the new shifting devices named dog clutches sq . measure introduced which assists in transmittal the desired output to the the majority of shaft by creating contact with the acceptable couple of the meshed gears.
A continuous mesh transmission typically includes 4 forward speeds and 1 reverse manual transmitting configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmitting was a great success in cars trade as presently there is a system which can provide needed torsion and quickness ratios wish by the vehicle to face the street challenges however still there have been several vital problems with this equipment that raised the question 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 particular 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 construction and working of constant mesh gearbox indicates that needed double engagement and disengagement of clutch for shifting a single gear.
f i.e. once driver needs to 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 applicable gear will happen, save for he presses the clutch pedal and produce the gear lever to the desired gear and unleash the clutch pedal and finally the required 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 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 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 primary 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 the clutch gear and the second gear; and the various other between your first gear and invert gear. The primary shaft is made splined and all of the gears are free to move on 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 is made to slide left by using the gear shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the remaining 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 correct, the first speed equipment and reverse gear are acquired respectively In this kind of gearbox, because all the gears are in continuous mesh, they are safe from being broken and unpleasant grinding audio does not happen while engaging and disengaging them.
Constant mesh gearbox is used for the smooth working of an automobile. They are used to increase the rotating power (Torque); this is accompanied by a decrease in swiftness. It is a kind of manual transmitting. The invention of earliest manual equipment system can be traced back again to the nineteenth century. There are multiple equipment ratios present which gives various torque and speed ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed lately contain all the gears mesh at any provided point of time.
In specialized terms, it could be thought as a gearbox in which all the gears are constantly in a state of mesh. The gears stay fixed at their initial positions. The gears will remain engaged at all times. Find out more about its construction, working, advantages, disadvantages and applications in this article.
Construction:
It is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct contact with the clutch and the primary shaft. Keeping in mind according to the equipment ratio, the acceleration of the counter shaft may be less that the swiftness 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 equipment.
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 relative to the gear ratio.
3. Dog clutch:
Dog clutch is unique feature of constant mesh gearbox. It is utilized 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 may be the transmission of power between the shafts. If the apparatus ratio is several, the primary shaft will continue to work at a quickness that is slower than the counter shaft, and vice versa. The set up of both reverse, as well as forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is divided into four parts. Each part goes to among the result gears, namely 1st, second, third and 4th. Gear ratios can be obtained for each of them. This could be done by the correct sliding of dog clutch over one's teeth of the chosen gearwheel. After this the road of the energy stream completes. This happens due to the locking movement of the result shaft.
Reverse gear selection:
The power will flow from the input shaft to the reverse gears. The power is then transmitted from the invert gear to the invert idler. The idler wheel changes the path of the rotation. In the case of forwarding direction gear selection, the output gears will rotate in a path opposite to the insight gears. However in the case of reverse equipment selection, the rotation can be in the same path as the insight shaft.
The steps are taken up 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. After this comes the neutral condition of the vehicle to be performed. Proper optimization of the engine's speed is required.
2. After the neutral equipment, one moves forward to the first equipment. The first equipment. This process is called double clutching. Inefficiency in executing the above steps might result in a harsh and gnashing sound.
Advantages and Disadvantages of Constant 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 extremely beneficial due to their quieter operating capabilities
There are numerous conditions which might cause harm. In the case of continuous mesh gearbox, any damage is suffered entirely by your dog clutch teeth. The teeth belonging to the apparatus tires stay intact. This is simply not the case for sliding mesh equipment box.
The other equipment boxes are noisy and create an undesired din.
Disadvantages:
It really is less efficient than the others because of higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is necessary. This is necessary to possess the spinning movements of the shaft.
Application:
A few of the vehicles which use this type of gearboxes are farm trucks, motorcycles, and large machinery.
In this kind of gearbox, all 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.electronic. one among the clutch equipment 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 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 top speed gear is obtained. When the left hand dog clutch meshes with second gear, the second gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the initial 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 does not happen while engaging and disengaging.