Constant Mesh Gear Box
Constant mesh gearbox can be a type of Transmission where all or the majority of the gears are always in mesh with one another, instead of a sliding-gear transmission, in which engagement is certainly obtained by sliding a few 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 so that power is certainly transmitted through them. The following diagram shows the set up of a continuous mesh gear box
Construction and functioning of a continuous mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. 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 activate the gears with result shaft dog clutch is used. the dog clutch can be shifted by the seletor fork moved by gear lever.To supply invert gearing a idler gear is used.
When the apparatus lever is pushed, the apparatus selector fork pushes the dog clutch. Your dog clutch engages the gear and the output shaft, thus power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is that a type 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 gadgets named dog clutches square measure introduced which helps in transmittal the required output to the the majority of shaft by creating contact with the acceptable couple of the meshed gears.
A constant mesh transmission typically comes with 4 forward speeds and 1 reverse manual transmitting configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh tranny was an excellent success in cars trade as presently there was a system which can provide needed torsion and velocity ratios desire by the vehicle to face the road challenges nevertheless still there have been several vital problems with this gear that raised the issue on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t an easy task because the shifting needed a particular technique that wasn’t whatsoever 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 since the name indicates that needed double engagement and disengagement of clutch for shifting one particular gear.
f i.e. once driver needs to shift the gear he preliminary presses the clutch pedal and generate the apparatus to the neutral, than once again he releases the clutch pedal and accelerate so as to extend the velocity of the lay-shaft in order that the meshing of relevant gear will take place, save for he presses the clutch pedal and generate the apparatus lever to the required gear and unleash the clutch pedal and at last 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 these gears may cause breakage to the apparatus teethes or continuous deterioration is there.
The shifting of gears could be 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 Constant 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 primary shaft: one between your clutch gear and the next gear; and the additional between your first gear and reverse gear. The main shaft is manufactured splined and all the gears are free to move onto it. Dog clutches can slide on the main 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 with the aid of the apparatus shift lever, it meshes with the clutch gear and the very best speed gear is obtained. When the left dog clutch meshes with the next gear on the main shaft, the next speed gear 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 type of gearbox, because all the gears are in continuous mesh, they are secure from being damaged and unpleasant grinding sound does not take place while engaging and disengaging them.
Constant mesh gearbox is utilized for the smooth operating of an automobile. They are accustomed to increase the rotating drive (Torque); that is accompanied by a decrease in quickness. 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 provides various torque and quickness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed recently contain all of the gears mesh at any given point of time.
In technical terms, it could be thought as a gearbox in which all of the gears are generally in a state of mesh. The gears remain fixed at their primary positions. The gears will stay engaged all the time. Find out more about its construction, working, advantages, disadvantages and applications in this post.
Construction:
It is made up of subsequent components:
1. Counter shaft or Lay Shaft:
This shaft is in direct contact with the clutch and the primary shaft. Remember according to the gear ratio, the quickness of the counter shaft could be much less that the speed of the engine. The gear ratio can be explained as the ratio of the teeth of driven gear to one’s teeth of the driver gear.
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 unique construction and working of constant mesh gearbox feature of constant mesh gearbox. It can be used for the coupling of any two shafts. This is completed by interference. Using a dog clutch, numerous gears could be locked to the result and input shafts.
4. Gears:
The primary work of the gears is the transmission of power between the shafts. If the gear 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, as well as 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 one of the result gears, namely first, second, third and 4th. Gear ratios can be obtained for each of them. This can be done by the proper sliding of dog clutch over the teeth of the selected gearwheel. After this the path of the energy movement completes. This happens due to 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 changes the direction of the rotation. Regarding forwarding direction equipment selection, the output gears will rotate in a direction opposite to the input gears. But in the case of reverse gear selection, the rotation is certainly in the same direction as the insight 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 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 necessary.
2. After the neutral equipment, one moves forward to the first equipment. The first gear. This process is called dual clutching. Inefficiency in performing the above measures might result in a harsh and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost benefit of the constant gear mesh may be the utilization of helical gears. The double helical gears and the helical gears are extremely beneficial owing to their quieter operating capabilities
There are numerous conditions which might cause harm. Regarding constant mesh gearbox, any harm is suffered completely by the dog clutch teeth. The teeth belonging to the apparatus wheels remain intact. This is simply not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an undesirable din.
Disadvantages:
It is less efficient than the others because of higher mesh teeth. Skill is required for it.
The dual clutch mesh is necessary. This is required to possess the spinning movements of the shaft.
Application:
Some of the vehicles designed to use this type of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this type of gearbox, all of the gears of the primary 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.electronic. one among the clutch gear and the second gear, and the additional 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 was created to slide left by means of the gear shift lever, it meshes with the clutch gear and the very best speed equipment is obtained. When the still left hands dog clutch meshes with second equipment, the second gear is obtained.
Similarly, by sliding right 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 continuous mesh and hence because of this, they are secure from being damaged and irritating grinding sound will not occur while engaging and disengaging.