Constant Mesh Gear Box
Constant mesh gearbox is certainly a type of Transmission in which all or the majority of the gears are always in mesh with one another, as opposed to a sliding-gear transmission, in which engagement is obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are selected by little Clutches that connect the many gear sets to their shafts to ensure that power is usually transmitted through them. The next diagram shows the arrangement of a constant mesh gear box
Construction and working of a constant mesh gear box
Constant equipment mesh gearbox employed helical gears for power transmission. The gears are rigidly fixed in the lay shaft. The gears in result shaft rotates freely without engaging with shaft, therefore not really transmitting power. The gears in both shafts are generally meshed together.
To activate the gears with result shaft dog clutch is used. the dog clutch is shifted by the seletor fork shifted by gear lever.To supply invert gearing a idler gear is used.
When the apparatus lever is pushed, the gear selector fork pushes your dog clutch. The dog clutch engages the apparatus and the result shaft, thus power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A constant 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 gadgets named dog clutches square measure introduced which assists in transmittal the desired output to the many shaft by creating contact with the acceptable pair of the meshed gears.
A constant 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.electronic. sliding mesh tranny was an excellent success in cars trade as presently there was a system which might provide needed torsion and swiftness ratios desire by the vehicle to face the road challenges nevertheless still there have been several vital problems with this gear that raised the query on its effectiveness and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t a simple task because the shifting needed a particular technique that wasn’t in any respect everybody’s cup of tea, a talented driver was needed for driving such vehicle, the special technique needed being Double-de-clutching.
Note – Double-de-clutching- it’s the technique since the name indicates that needed dual engagement and disengagement of clutch for shifting one particular gear.
f i.e. once driver must shift the gear he preliminary presses the clutch pedal and produce the gear to the neutral, than once more he releases the clutch pedal and accelerate in order to extend the quickness of the lay-shaft in order that the meshing of applicable gear will occur, save for he presses the clutch pedal and generate the gear lever to the desired equipment and unleash the clutch pedal and at last the desired gear is obtained.
Since the gears should be meshed square measure in construction and working of constant mesh gearbox continuous rotation with a completely different speed compared to the meshing of these gears may cause breakage to the apparatus teethes or continuous wear and tear 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 main shaft are in constantly meshed with the corresponding gears of the layshaft or countershaft. As well dog clutches are given on the primary shaft: one between your clutch gear and the second gear; and the other between your first gear and invert gear. The primary shaft is manufactured splined and all of 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 completely fixed with it.
When the left dog clutch is made to slide to the left with the aid of the gear shift lever, it meshes with the clutch gear and the top 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. Likewise, by sliding the right-hand dog clutch to the left and correct, the first speed equipment and reverse equipment are attained respectively In this type of gearbox, because all of the gears are in constant mesh, they are safe from being broken and unpleasant grinding sound does not happen while engaging and disengaging them.
Continuous mesh gearbox is used for the smooth functioning of an automobile. They are accustomed to increase the rotating push (Torque); this is accompanied by a reduction in swiftness. It is a type of manual transmission. The invention of earliest manual gear system can be traced back again to the nineteenth century. There are multiple equipment ratios present which gives various torque and quickness ratio. Along with this, 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 could be thought as a gearbox where all the gears are at all times in a state of mesh. The gears stay fixed at their unique positions. The gears will remain engaged all the time. Find out more about its construction, working, advantages, drawbacks and applications in this post.
Construction:
It is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct connection with the clutch and the main shaft. Remember according to the equipment ratio, the speed of the counter shaft may be less that the speed of the engine. The gear ratio can be explained as the ratio of the 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 manufactured available to the main shaft through the gears from the counter shaft. That 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. This is completed by interference. Utilizing a dog clutch, various gears can be locked to the output and input shafts.
4. Gears:
The main work of the gears may be the transmission of power between your shafts. If the gear ratio is more than one, the main shaft will work at a acceleration that is slower compared to the counter shaft, and vice versa. The set up of both reverse, as well as forward gears, is present.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is divided into four parts. Each part goes to among the result gears, namely first, second, third and fourth. Gear ratios can be acquired for each of these. This can be done by the proper sliding of dog clutch over the teeth of the chosen gearwheel. After this the path of the energy stream completes. This happens because of the locking motion of the output shaft.
Reverse gear selection:
The energy will flow from the input shaft to the reverse gears. The power is then transmitted from the invert gear to the reverse idler. The idler wheel will change the direction of the rotation. In the case of forwarding direction equipment selection, the result gears will rotate in a direction opposite to the insight gears. However in the case of reverse equipment selection, the rotation is usually in the same path as the input shaft.
The steps are taken to change any gear in the constant mesh gearbox system:
1. The first step when one really wants to modify the gear would be the pressing of the clutch. Following this comes the neutral state of the automobile to be performed. Proper optimization of the engine’s speed is necessary.
2. After the neutral equipment, one moves forward to the first gear. The first equipment. This process is called dual clutching. Inefficiency in performing the above techniques might lead to a severe and gnashing sound.
Advantages and Disadvantages of Continuous Mesh Gearbox:
Advantages:
The first and foremost advantage 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 damage is suffered entirely by your dog clutch teeth. The teeth belonging to the gear wheels remain intact. This is simply not the case for sliding mesh gear box.
The other equipment 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 double clutch mesh is necessary. This is necessary to have the spinning motions of the shaft.
Application:
Some of the vehicles designed to use this type of gearboxes are farm trucks, motorcycles, and large machinery.
In this type 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 provided on the main shaft i.electronic. one in between the clutch gear and the second gear, and the additional between the first equipment and the reverse equipment.
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 hand dog clutch is made to slide to the left by means of the apparatus change lever, it meshes with the clutch gear and the top speed gear is obtained. When the still left hand dog clutch meshes with second gear, the next gear is obtained.
Similarly, by sliding right hand dog clutch to the left and right, the initial speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in continuous mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not occur while engaging and disengaging.