Constant Mesh Gear Box
Constant mesh gearbox is usually a type of Transmission where all or most of the gears are always in mesh with one another, as opposed to a sliding-gear transmission, where engagement is usually obtained by sliding a few of the gears along a shaft into mesh. In a constant-mesh manual gearbox, Equipment ratios are selected by small Clutches that connect the many gear sets to their shafts so that power is definitely 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 transmitting. The gears are rigidly fixed in the lay shaft. The gears in result shaft rotates freely without engaging with shaft, thus not really transmitting power. The gears in both shafts are always meshed together.
To engage the gears with result shaft dog construction and working of constant mesh gearbox Clutch is used. the dog clutch is usually shifted by the seletor fork moved by gear lever.To supply invert gearing a idler equipment is used.
When the apparatus lever is pushed, the apparatus selector fork pushes your dog clutch. Your dog clutch engages the gear and the output shaft, therefore power from lay shaft at this point 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 gadgets named dog clutches sq . measure introduced which helps in transmittal the desired output to the most shaft by creating connection 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 want Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh tranny was an excellent success in vehicles trade as currently there is a system which can provide needed torsion and acceleration ratios want by the automobile to face the road challenges nevertheless still there were several vital problems with this equipment that raised the issue on its performance and responsibility. the problems long-faced were as follows-
The shifting of gears wasn’t a simple task since the shifting needed a particular technique that wasn’t in any respect everybody’s cup of tea, a talented driver was needed for generating 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 a single gear.
f i.e. once driver must shift the gear he initial presses the clutch pedal and generate the apparatus to the neutral, than once again he releases the clutch pedal and accelerate in order to extend the quickness of the lay-shaft to ensure that the meshing of applicable gear will take place, 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 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 gear 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 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 next gear; and the additional between your first gear and reverse gear. The primary shaft is manufactured splined and all of 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 is made to slide to the left by making use of the apparatus shift lever, it meshes with the clutch gear and the top speed gear is obtained. When the still left dog clutch meshes with the next gear on the main shaft, the second speed equipment is achieved. Similarly, by sliding the right-hand dog clutch left and correct, the first speed gear and reverse gear are acquired respectively In this kind of gearbox, because all of the gears are in continuous mesh, they are secure from being broken and unpleasant grinding sound does not take place while engaging and disengaging them.
Continuous mesh gearbox can be used for the smooth working of an automobile. They are accustomed to increase the rotating force (Torque); that is accompanied by a reduction in velocity. It is a kind of manual transmitting. The invention of earliest manual gear system could be traced back to the nineteenth century. There are multiple gear ratios present which gives various torque and swiftness ratio. Along with this, the reverse mechanism is also present. This manual transmissions which are developed recently contain all the gears mesh at any provided point of time.
In specialized terms, it could be defined as a gearbox in which all the gears are usually in a state of mesh. The gears stay fixed at their primary positions. The gears will remain engaged all the time. Find out more about its structure, 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 connection with the clutch and the primary shaft. Remember according to the gear ratio, the speed of the counter shaft may be much less that the speed of the engine. The gear ratio can be defined as the ratio of the teeth of driven gear to the teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the automobile. The power is made available to the primary 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 can be used for the coupling of any two shafts. This is completed by interference. Using a dog clutch, various 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 apparatus ratio is several, the primary shaft will continue to work at a speed that is slower than the counter shaft, and vice versa. The set up of both reverse, along with forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is divided into four parts. Each component goes to among the output gears, namely 1st, second, third and 4th. Gear ratios can be obtained for each of these. This is often done by the proper sliding of dog clutch over the teeth of the selected gearwheel. After this the path of the energy flow 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 after that transmitted from the reverse gear to the reverse idler. The idler wheel will change the path of the rotation. In the case of forwarding direction equipment selection, the result gears will rotate in a direction opposite to the input gears. However in the case of reverse gear selection, the rotation is definitely 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 change the gear would be the pressing of the clutch. Following this comes the neutral state of the automobile to be achieved. Proper optimization of the engine’s speed is required.
2. After the neutral equipment, one moves ahead to the first gear. The first gear. This process is called dual clutching. Inefficiency in executing the above guidelines might result in a severe and gnashing sound.
Benefits and drawbacks of Constant Mesh Gearbox:
Advantages:
The first and foremost benefit of the constant gear mesh may be the usage of helical gears. The double helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are many conditions which might cause harm. Regarding continuous mesh gearbox, any harm is suffered entirely by the dog clutch teeth. One’s teeth belonging to the apparatus tires stay intact. This is simply not the case for sliding mesh gear box.
The other gear boxes are noisy and create an undesirable din.
Disadvantages:
It is less efficient compared to the others due to higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is necessary. This is necessary to have the spinning motions of the shaft.
Application:
Some of the vehicles designed to use this kind of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this kind of gearbox, all of 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 primary shaft i.electronic. one in between the clutch gear 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 of the gears on the counter shaft are rigidly fixed with it.
As and when the left hands dog clutch was created to slide left by means of the apparatus change lever, it meshes with the clutch equipment and the top speed equipment 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 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 safe from being damaged and irritating grinding sound does not take place while engaging and disengaging.