Constant Mesh Gear Box
Constant mesh gearbox is definitely 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 definitely obtained by construction and working of constant mesh gearbox sliding some of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are selected by little Clutches that connect the various gear sets with their shafts to ensure that power can be transmitted through them. The next diagram shows the arrangement of a constant mesh gear box
Construction and operating 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 really transmitting power. The gears in both shafts are at all times meshed together.
To engage the gears with output shaft dog clutch is used. the dog clutch is usually shifted by the seletor fork shifted by gear lever.To provide invert gearing a idler equipment is used.
When the gear lever is pushed, the gear selector fork pushes your dog clutch. The dog clutch engages the gear and the result shaft, therefore power from lay shaft now transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is a type of manual transmission where sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears as well as the new shifting products named dog clutches sq . 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 constant mesh transmission typically comes with 4 forward speeds and 1 reverse manual tranny configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh tranny was a great success in vehicles trade as presently there is a system which might provide needed torsion and acceleration ratios wish by the automobile to face the road challenges however still there were several vital problems with this gear that raised the query on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t an easy task since the shifting needed a special technique that wasn’t in any respect 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 because the name indicates that needed double engagement and disengagement of clutch for shifting 1 gear.
f i.electronic. once driver needs to shift the gear he preliminary presses the clutch pedal and create the gear to the neutral, than once more he releases the clutch pedal and accelerate in order to extend the velocity of the lay-shaft to ensure that the meshing of relevant gear will happen, save for he presses the clutch pedal and produce the apparatus lever to the required gear and unleash the clutch pedal and finally 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 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. As well dog clutches are provided on the main shaft: one between the clutch equipment and the next gear; and the other between your first gear and invert gear. The main shaft is manufactured splined and all the gears are absolve to move onto it. Dog clutches can slide on the primary shaft and rotates with it. All 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 main shaft, the second speed equipment is achieved. Likewise, by sliding the right-hand dog clutch left and correct, the first speed equipment and reverse equipment 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 take place while engaging and disengaging them.
Continuous mesh gearbox is used for the smooth operating of an automobile. They are accustomed to increase the rotating drive (Torque); that is accompanied by a reduction in quickness. It is a kind of manual transmitting. The invention of earliest manual gear system could be traced back again to the nineteenth century. There are multiple equipment ratios present which provides various torque and swiftness ratio. Along with this, the reverse mechanism is also present. This manual transmissions which are developed lately contain all the gears mesh at any provided point of time.
In technical terms, it could be defined as a gearbox where all of the gears are often in circumstances of mesh. The gears stay fixed at their initial positions. The gears will stay engaged at all times. Learn more about its construction, 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 speed of the counter shaft may be much less that the velocity of the engine. The apparatus ratio can be defined as the ratio of the teeth of driven equipment to the teeth of the driver gear.
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 continuous mesh gearbox. It is utilized for the coupling of any two shafts. That is done by interference. Using a dog clutch, different gears can be locked to the result and input shafts.
4. Gears:
The primary work of the gears is the transmission of power between your shafts. If the apparatus ratio is more than one, the primary shaft will continue to work at a velocity 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 component goes to among the output gears, namely initial, second, third and fourth. Gear ratios can be acquired for each of these. This is often done by the correct sliding of dog clutch over the teeth of the chosen gearwheel. After this the path of the energy circulation completes. This happens because of 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 after that transmitted from the invert gear to the reverse idler. The idler wheel changes the direction of the rotation. Regarding forwarding direction gear selection, the result gears will rotate in a direction opposite to the insight gears. But in the case of invert equipment selection, the rotation can be 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 wants to change the gear would 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 required.
2. After the neutral gear, one moves ahead to the first gear. The first equipment. This process is known as dual clutching. Inefficiency in carrying out the above actions might lead to a severe and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the constant gear mesh is the utilization of helical gears. The dual helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are numerous conditions which can cause harm. In the case of continuous mesh gearbox, any harm is suffered completely by the dog clutch teeth. One’s 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 really is less efficient compared to the others because of higher mesh teeth. Skill is necessary for it.
The double clutch mesh is necessary. This is necessary to possess the spinning actions of the shaft.
Application:
Some of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and large 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 primary shaft i.e. one in between the clutch gear and the second gear, and the other between the first gear and the reverse gear.
Your 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 hand dog clutch is made to slide to the left by means of the apparatus shift lever, it meshes with the clutch equipment and the very best speed equipment is obtained. When the left hands dog clutch meshes with second equipment, the second gear is obtained.
Similarly, by sliding correct hand dog clutch left and right, the 1st speed gear and reverse gear are obtained respectively.
In this type 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 take place while engaging and disengaging.