The output shaft is a splined shaft, so that the gear or synchronizer can be moved to engage or disengage. The bearings are required to support the rotating part and reduce friction. The gear box has both a counter and main shaft which is supported by the bearing. Gears are used to transmitting the power from one shaft to another shaft.
The amount of torque transmitted through the gears depends on the number of teeth and the size of the gears. All gears except those on the main shaft are fixed to their respective shafts; They can slide in any of the directions along the shaft. Gear selectors are simple devices that use a lever that selects gears to engage in disengage mechanisms.
The motion of the lever slides the engaging part on the shaft. It depends on the type of gearbox whether the lever slides the gear or synchronizer that are already forged along the main shaft.
It is the simplest type of gearbox. In this gearbox, spur gears are used. The Figure shows the construction of a sliding mesh type transmission having three forward and one reverse speeds. There are three gears 1, 6 and 5 attached on the main shaft and four gears 2, 3,4 and 7 on the layshaft.
The two gears on the main shaft 6 and 5 can be slided by a shafting yoke and mesh with the gears 3 and 4 on a layshaft. Therefore, it is called a sliding mesh gearbox. A separate idler gear 8 is mounted on the idler shaft. Figure shows the construction of a constant mesh type gearbox having three forward and one reverse speeds. In this type of gearbox, all gears are constantly in mesh and dog clutches are used for engaging and disengaging the gears.
The dog clutches D and D2 are mounted on the main shaft. One D2 is connected between clutch gear and reverse gear whereas the other D is placed between low speed gear and reverse gear. The splines are provided on the main shaft for the linear movement of dogs. Dog clutch can slide on the shaft and rotate along with it. All gears are rigidly fixed on the counter shaft. All main shaft and layshaft gears, and idler gears are engaged by dog clutch to obtain opposite and slow speed.
Only reverse gears are spur gear type and all others are helical gears. As compared with the sliding mesh type, the constant mesh type gearbox meshes more readily with the gears having less danger of damaging during meshing because the gear diameters are smaller with few numbers of teeth. So, this type has more defects when compared to a synchromesh type.
The necessity of double clutching is needed so that it is not used to any large extent. Synchromesh gearbox uses synchronizer instead of sliding dog clutches to affect the ratio change. Conventional — non-electric — cars are powered by internal combustion engines, those engines have to be running spinning to develop power and develop their best power over a relatively narrow RPM band — maybe 1, to 2, RPM.
When you shift gears what you're doing is to matching the engine speed to the speed you want to be traveling down the road. This lets you operate the engine at a relatively fixed "good" speed while allowing you to vary your speed. The relevance to maintenance and repair is that frequent operation outside of that band could damage the engine.
If you run the engine too slow, called "lugging," the pressure in the cylinders can become high enough to do damage. If you run the engine too fast, "over-revving" it, you run into another set of problems. At high speeds you will see more heat build-up and problems like "valve float" will start to creep in. Since many parts of the engine are spinning and changing direction the balance of parts like pistons, connecting rods, and the crankshaft all become critical as the engine speed goes up.
The transmission and shifting gears gives you a way to avoid these problems. Gears are required to keep the engine at rotational speeds where it creates a desirable amount of power across a wide range of road speeds. Generally, the faster an engine turns, the more fuel it consumes, and the more power it makes. Engines are also only capable of rotating to a maximum speed redline.
Gears are designed for a given limited range of road speed. First gear allows the engine to provide a large amount of power at very low speed. Once a reasonable road speed is achieved and the engine reaches the upper portion of it's usable range, a higher gear is selected.
Smooth gear changing is the first of three key foundation skills you need to learn, the others being steering and clutch control. Gears can be changed up or down.
This has nothing to do with the direction you move the gear lever, it simply means that you change to a higher gear 4 or 5 or a lower gear 1 or 2. The basic rule is that you change up through the gears as the speed of the car increases and down when you need more power from the engine. For example, you would change down to a lower gear when climbing a hill or pulling away at low speed. First gear provides the most pulling power but the least potential for speed, whilst fifth gear which provides the least pulling power allows the greatest range of speed.
The following table indicates typical speed and revs for changing gears up or down. As the car increases speed, change up through the gears. But opting out of some of these cookies may have an effect on your browsing experience. Necessary Necessary. Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information. Non-necessary Non-necessary.
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