Constant Mesh Gear Box
Constant mesh gearbox is usually a kind of Transmission in which all or most 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 selected by little Clutches that connect the many gear sets with 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 functioning 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 often meshed together.
To engage the gears with output shaft dog clutch can be used. the dog clutch is shifted by the seletor fork moved by gear lever.To provide reverse gearing a idler equipment is used.
When the apparatus lever is pushed, the apparatus selector fork pushes your dog clutch. The dog clutch engages the gear and the result shaft, hence power from lay shaft right now transmitted to result shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is a kind of manual transmission in which sliding gears from the sliding mesh gearbox is replaced with the constantly meshed combines of gears as well as the new shifting devices named dog clutches sq . measure introduced which helps in transmittal the desired output to the many shaft by creating connection with the acceptable pair of the meshed gears.
A continuous mesh transmission typically includes 4 forward speeds and 1 reverse manual transmission configuration.
Why will we want Constant Mesh Transmission?
The introduction of initial transmission system i.electronic. sliding mesh transmission was a great success in vehicles trade as currently there was a system which might provide needed torsion and rate ratios really want by the vehicle to face the street challenges however still there were several vital problems with this equipment that raised the question on its efficiency and responsibility. the issues long-faced were as follows-
The shifting of gears wasn’t a simple task because the shifting needed a special technique that wasn’t in any respect everybody’s cup of tea, a talented driver was necessary 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 1 gear.
f i.e. once driver must shift the apparatus he initial 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 swiftness of the lay-shaft to ensure that the meshing of applicable gear will occur, save for he presses the clutch pedal and produce the apparatus lever to the desired equipment and unleash the clutch pedal and finally the desired gear is obtained.
Since the gears are to be meshed square measure in continuous rotation with a totally different speed compared to the meshing of those gears will cause breakage to the gear teethes or continuous deterioration is there.
The shifting of gears could be 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 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 your clutch gear and the second gear; and the other between the first gear and invert gear. The primary shaft is made 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 with the help of the gear shift lever, it meshes with the clutch gear and the very best speed gear is obtained. When the left dog clutch meshes with the second gear on the primary shaft, the second speed equipment is achieved. Likewise, 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 constant mesh, they are secure from being damaged and unpleasant construction and working of constant mesh gearbox grinding audio does not happen while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth working of a car. They are used to increase the rotating pressure (Torque); this is accompanied by a reduction in rate. It is a type of manual transmitting. The invention of earliest manual gear system could be traced back to the nineteenth century. There are multiple equipment ratios present which provides various torque and velocity 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 specialized terms, it can be defined as a gearbox where all the gears are usually in circumstances of mesh. The gears stay fixed at their unique positions. The gears will remain engaged at all times. Find out more about its building, working, advantages, drawbacks and applications in this article.
Construction:
It 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. Keeping in mind according to the equipment ratio, the rate of the counter shaft may be less that the acceleration of the engine. The apparatus ratio can be explained as the ratio of the teeth of driven equipment to one’s teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the vehicle. The power is made available to the main shaft through the gears from the counter shaft. That is done relative to the gear ratio.
3. Dog clutch:
Dog clutch is special feature of constant mesh gearbox. It is used for the coupling of any two shafts. That is done by interference. Using a dog clutch, different gears can be locked to the output and input shafts.
4. Gears:
The primary work of the gears is the transmission of power between your shafts. If the apparatus ratio is several, the primary shaft will work at a velocity that is slower than the counter shaft, and vice versa. The arrangement of both reverse, and also forward gears, is present.
Working:
Forward gear selection:
From the input shaft, the energy starts flowing and is split into four parts. Each component goes to among the output gears, namely first, 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 road of the energy flow completes. This happens due to the locking motion of the output shaft.
Reverse gear selection:
The power will flow from the input shaft to the reverse gears. The energy is then transmitted from the reverse 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 direction opposite to the insight gears. However in the case of invert equipment selection, the rotation is usually in the same path as the input shaft.
The steps are taken to change any gear in the continuous 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 performed. Proper optimization of the engine’s speed is required.
2. After the neutral gear, one moves forwards to the first gear. The first gear. This process is known as double clutching. Inefficiency in executing the above techniques might result in a severe and gnashing sound.
Advantages and Disadvantages of Constant Mesh Gearbox:
Advantages:
The first and foremost advantage of the continuous gear mesh is the usage of helical gears. The dual helical gears and the helical gears are really beneficial due to their quieter operating capabilities
There are various conditions which can cause harm. In the case of continuous mesh gearbox, any harm is suffered entirely by your dog clutch teeth. One’s teeth belonging to the gear tires stay intact. This is not the case for sliding mesh gear box.
The other equipment boxes are noisy and create an unwanted din.
Disadvantages:
It really is less efficient compared to the others due to higher mesh teeth. Skill is required for it.
The double clutch mesh is necessary. This is required to possess the spinning motions of the shaft.
Application:
A few of the vehicles which use this kind of gearboxes are farm trucks, motorcycles, and large machinery.
In this kind of gearbox, all 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 provided on the main shaft i.e. one in between the clutch equipment and the next gear, and the other between the first gear and the reverse gear.
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 apparatus change lever, it meshes with the clutch equipment and the top speed gear is obtained. When the left hands dog clutch meshes with second gear, the next gear is obtained.
Similarly, by sliding correct hand dog clutch to the left and right, the 1st speed gear and reverse gear are obtained respectively.
In this kind of gearbox, all of the gears are in constant mesh and hence for this reason, they are safe from being damaged and irritating grinding sound will not happen while engaging and disengaging.