Constant Mesh Gear Box
Constant mesh gearbox is a type of Transmission in which all or the majority of the gears are always in mesh with each other, 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 small Clutches that connect the many gear sets to their shafts so that power is definitely transmitted through them. The following diagram shows the set up of a constant mesh gear box
Construction and working of a continuous mesh gear box
Constant gear mesh gearbox employed helical gears for power tranny. The gears are rigidly set 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 often meshed together.
To activate the gears with result shaft dog clutch is used. the dog clutch is certainly shifted by the seletor fork relocated by gear lever.To supply invert gearing a idler gear is used.
When the apparatus lever is pushed, the apparatus selector fork pushes the dog clutch. Your dog clutch engages the apparatus and the output shaft, thus power from lay shaft at this point transmitted to output shaft.
CONSTANT MESH GEARBOX
A continuous mesh transmission is 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 devices named dog clutches square measure introduced which helps in transmittal the desired output to the many shaft by creating contact with the acceptable couple of the meshed gears.
A constant mesh transmission typically includes 4 forward speeds and 1 reverse manual transmission configuration.
Why will we wish Constant Mesh Transmission?
The introduction of initial transmission system i.e. sliding mesh transmission was an excellent success in cars trade as currently there is a system which can offer needed torsion and velocity ratios need by the automobile to face the street challenges nevertheless 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 an easy task because the shifting needed a special 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 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 again he releases the clutch pedal and accelerate so as to extend the quickness of the lay-shaft to ensure that the meshing of relevant 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 are to be meshed square measure in continuous rotation with a completely different speed compared to the meshing of these gears will cause breakage to the apparatus 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 different types 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 various other between the first gear and invert gear. The primary shaft is manufactured splined and all of the gears are free to move on it. Dog clutches can slide on the primary shaft and rotates with it. All of the gears on the countershaft are completely fixed with it.
When the left dog clutch is made to slide 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 main shaft, the next speed gear is achieved. Similarly, by sliding the right-hand dog clutch to the left and right, the first speed gear and reverse gear are obtained respectively In this type of gearbox, because all of the gears are in constant mesh, they are secure from being damaged and unpleasant grinding sound does not happen while engaging and disengaging them.
Constant mesh gearbox can be used for the smooth working of a car. They are accustomed to increase the rotating push (Torque); this is accompanied by a decrease in rate. It is a type of manual tranny. The invention of earliest manual equipment system can be traced back to the nineteenth century. There are multiple gear ratios present which gives various torque and rate ratio. Additionally, the reverse mechanism is also present. This manual transmissions which are developed recently contain all the gears mesh at any given point of time.
In technical terms, it can be thought as a gearbox in which all the gears are usually in circumstances of mesh. The gears stay fixed at their original positions. The gears will construction and working of constant mesh gearbox remain engaged all the time. Learn more about its structure, working, advantages, disadvantages and applications in this article.
Construction:
It really is made up of subsequent components:
1. Counter shaft or Lay Shaft:
This shaft is in direct connection with the clutch and the main shaft. Keeping in mind according to the gear ratio, the swiftness of the counter shaft may be less that the quickness of the engine. The gear ratio can be defined as the ratio of one’s teeth of driven equipment to one’s teeth of the driver equipment.
2. Main shaft:
This shaft operates the speed of the automobile. The power is manufactured available to the main shaft through the gears from the counter shaft. This is done in accordance with 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 completed by interference. Utilizing a dog clutch, numerous 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 apparatus ratio is several, the primary shaft will continue to work at a quickness that is slower than the counter shaft, and vice versa. The arrangement of both reverse, in addition to forward gears, exists.
Working:
Forward gear selection:
From the input shaft, the power starts flowing and is split into four parts. Each part goes to one of the result gears, namely 1st, second, third and 4th. Gear ratios can be obtained for each of them. 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 stream 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 power is then transmitted from the invert gear to the invert 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 input gears. However in the case of reverse gear selection, the rotation is definitely in the same direction as the insight shaft.
The steps are taken to change any gear in the constant mesh gearbox system:
1. The first rung on the ladder when one wants to change the gear will 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 equipment. The first gear. This process is called dual clutching. Inefficiency in performing the above techniques might result in a harsh and gnashing sound.
Benefits and drawbacks of Continuous Mesh Gearbox:
Advantages:
The first and foremost benefit of the constant gear mesh may be the utilization of helical gears. The dual helical gears and the helical gears are really beneficial owing to their quieter operating capabilities
There are various conditions which might cause harm. In the case of constant mesh gearbox, any harm is suffered entirely by your dog clutch teeth. The teeth belonging to the apparatus wheels stay intact. This is not the case for sliding mesh equipment box.
The other gear boxes are noisy and create an unwanted din.
Disadvantages:
It is less efficient than the others due to higher mesh teeth. Skill is necessary for it.
The dual clutch mesh is required. This is required to have the spinning motions of the shaft.
Application:
A few of the vehicles designed to use this type of gearboxes are farm trucks, motorcycles, and weighty machinery.
In this type of gearbox, all 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 given on the main shaft i.e. one in between the clutch gear and the second gear, and the various other between the first equipment 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 left by means of the gear change lever, it meshes with the clutch equipment and the very best 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 first speed gear and reverse gear are obtained respectively.
In this type of gearbox, all of the gears are in continuous mesh and hence for this reason, they are secure from being damaged and irritating grinding sound will not happen while engaging and disengaging.