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 each other, as opposed to a sliding-gear transmission, where engagement is usually obtained by sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are chosen by small Clutches that connect the many gear sets with their shafts so that power is usually transmitted through them. The next diagram shows the set up of a continuous mesh gear box
Construction and operating of a constant mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. The gears are rigidly fixed in the lay shaft. The gears in construction and working of constant mesh gearbox result shaft rotates freely without engaging with shaft, thus not really transmitting power. The gears in both shafts are at all times meshed together.
To engage the gears with result shaft dog clutch can be used. the dog clutch can be shifted by the seletor fork moved by gear lever.To provide reverse gearing a idler gear is used.
When the gear lever is pushed, the gear selector fork pushes the dog clutch. Your dog clutch engages the apparatus and the result shaft, therefore power from lay shaft right now transmitted to result shaft.
CONSTANT MESH GEARBOX
A constant mesh transmission is a form 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 required output to the most 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 wish Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh tranny was an excellent success in vehicles trade as currently there was a system which might offer needed torsion and acceleration ratios want by the automobile to face the road challenges however still there have been several vital issues with this gear that raised the question on its performance 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 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 must shift the apparatus he initial presses the clutch pedal and produce the gear to the neutral, than once more he releases the clutch pedal and accelerate so as to extend the rate of the lay-shaft to ensure that the meshing of applicable 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 should be meshed square measure in continuous rotation with a totally different speed than 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 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 main shaft are in constantly meshed with the corresponding gears of the layshaft or countershaft. Too dog clutches are provided on the main shaft: one between your clutch gear and the second gear; and the other between your first gear and reverse gear. The main shaft is made splined and all the gears are absolve to move on it. Dog clutches can slide on the primary shaft and rotates with it. All the gears on the countershaft are completely fixed with it.
When the left dog clutch was created to slide to the left by using the apparatus shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the remaining dog clutch meshes with the next gear on the primary 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 equipment are acquired respectively In this type of gearbox, because all the gears are in constant mesh, they are safe from being broken and unpleasant grinding sound does not happen while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth functioning of an automobile. They are accustomed to increase the rotating force (Torque); that is accompanied by a decrease in speed. It is a type of manual tranny. The invention of earliest manual gear system could be traced back again to the nineteenth century. There are multiple gear ratios present which provides various torque and quickness ratio. Additionally, the reverse mechanism can be present. This manual transmissions which are developed lately contain all the gears mesh at any given point of time.
In specialized terms, it could be thought as a gearbox where all of the gears are at all times in a state of mesh. The gears remain fixed at their unique positions. The gears will remain engaged at all times. Learn more about its structure, working, advantages, drawbacks and applications in this post.
Construction:
It really is made up of following components:
1. Counter shaft or Lay Shaft:
This shaft is in direct contact with the clutch and the main shaft. Remember according to the equipment ratio, the swiftness of the counter shaft may be much less that the swiftness of the engine. The apparatus ratio can be explained as the ratio of one’s teeth of driven equipment to the 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. That is done in accordance with the gear ratio.
3. Dog clutch:
Dog clutch is particular feature of constant mesh gearbox. It is utilized for the coupling of any two shafts. This is completed by interference. Utilizing a dog clutch, different gears can be locked to the result and input shafts.
4. Gears:
The main work of the gears may be 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 than the counter shaft, and vice versa. The arrangement of both reverse, and also 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 these. 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 movement completes. This happens because of the locking movement 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 invert gear to the invert idler. The idler wheel will change the path of the rotation. In the case of forwarding direction gear selection, the result gears will rotate in a path opposite to the input gears. However in the case of invert gear selection, the rotation is usually 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. Following this comes the neutral state of the automobile to be performed. Proper optimization of the engine’s speed is required.
2. After the neutral equipment, one moves forwards to the first equipment. The first gear. This process is known as double clutching. Inefficiency in performing the above methods might lead to a harsh and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
Advantages:
The first and foremost advantage of the constant gear mesh is the usage of helical gears. The double helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are numerous conditions which might cause harm. In the case of continuous mesh gearbox, any damage is suffered completely by the dog clutch teeth. The teeth belonging to the gear wheels remain intact. This is simply not the case for sliding mesh equipment box.
The other equipment boxes are noisy and create an undesirable din.
Disadvantages:
It is less efficient compared to the others due to higher mesh teeth. Skill is required for it.
The double clutch mesh is required. This is necessary to have the spinning motions of the shaft.
Application:
Some of the vehicles which use this type of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this type of gearbox, all the gears of the main 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 gear and the next gear, and the various other between the first gear 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 set with it.
As and when the left hand dog clutch is made to slide to the left by means of the gear shift lever, it meshes with the clutch equipment and the top 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 initial speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all the gears are in constant mesh and hence because of this, they are secure from being damaged and irritating grinding sound does not happen while engaging and disengaging.