From the time the car is driven off the lot, to the time the belt needs replacing thousands of kilometers later, it synchronizes the two shafts exactly. Again, exact accounting of teeth and revolutions can be applied with these machines.Ī belt with teeth, called the timing belt, is used in some internal combustion engines to exactly synchronize the movement of the camshaft with that of the crankshaft, so that the valves open and close at the top of each cylinder at exactly the right time relative to the movement of each cylinder. Special gears called sprockets can be coupled together with chains, as on bicycles and some motorcycles. In other words, the gear ratio is proportional to ratio of the gear diameters and inversely proportional to the ratio of gear speeds.īelts can have teeth in them also and be coupled to gear-like pulleys. Since the diameter is equal to twice the radius Since the number of teeth is also proportional to the circumference of the gear wheel (the bigger the wheel the more teeth it has) the gear ratio can also be expressed as the relationship between the circumferences of both wheels (where d is the diameter of the smaller wheel and D is the diameter of the larger wheel): Since the intermediate (idler) gear contacts directly both the smaller and the larger gear it can be removed from the calculation, also giving a ratio of 42/13 = 3.23. Suppose the largest gear in the picture has 42 teeth, the gear ratio between the second and third gear is thus 21/42, or 1/2, and for every revolution of the smallest gear, the largest gear turns 0.62/2, or 0.31 revolution, a total reduction of about 1:3.23. In practical terms, the idler gear turns more slowly. It also means that for every one revolution of the pinion, the idler gear has made 1/1.62, or 0.62, revolutions. The ratio means that the pinion gear must make 1.62 revolutions to turn the idler gear 1 revolution. In the picture to the right, the smaller gear (known as the pinion) has 13 teeth, while the second, larger gear (known as the idler gear) has 21 teeth.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |