The gear ratio of any gearbox is one of its most important characteristics. It can be determined by the ratio of the number of teeth of the driving and driven gears.
The gear ratio of the gearbox is a very important indicator, for example, two gearboxes that are absolutely identical in appearance (the same company and model) can have different gear ratios, which makes them completely non-interchangeable. Therefore, experienced motorists advise: before buying or replacing a faulty gearbox, especially on a car with a drive on both axles, you must first determine the gear ratio of the gearbox.
Naturally, if when buying a new or used gearbox, the former owner / seller cannot name the gear ratio, then it is better not to purchase it. After all, it would be very stupid to refuel, for example, a car from a column where the brand of fuel is not indicated. And the consequences of this error will be more significant than low-quality gasoline.
All the arguments that the gearbox sold from a car with a similar engine are completely not convincing, because:
- The semantic load of this argument is similar to that which would be if you were told that the KamAZ gearbox sold has the same color as your car.
- This is not a guarantee of truth, but it can be a fraud or a mistake, while the seller has one goal - to sell the product faster.
There are several ways to determine the gear ratio. But first, it’s better to consider the types of gearboxes that are generally available and are installed on various machines and mechanisms.
1. Helical gears. They are most often used in mechanisms of hoisting machines, as well as in other areas of production, where the regime of loads is repeated and short-term. They have high efficiency and great durability.
2. Bevel gears. They have a more complex device than cylindrical ones. They have the most favorable ratio of performance and compactness. They are used in crane structures.
3. Worm gearboxes. Designed to carry out rotation between the crossing shafts, i.e. by means of a worm and a mating worm wheel. They are used in hoisting-and-transport machines, machine tools (mainly metal-cutting ones), as well as in trolley buses. Pluses - smoothness of work and noiselessness. Cons - low efficiency and increased wear. And the gear ratio of the gearbox does not quite meet the necessary requirements.
4. Planetary gearboxes. They have the smallest specific metal consumption, but a large load capacity.
5. Wave reducers. They are mainly used in the space rocket or defense industry.
6. Combined gearboxes. This is the use of several types of gears in one housing.
The gear ratio of a car gearbox can be determined in the following ways:
1. The catalog method. This is the easiest way (it can be applied without leaving your home), but it is also not the most reliable. Determine by vehicle VIN. To do this, write off the number from the certificate of registration of the car. Then in one of the online catalogs of auto parts stores, enter the number in the search bar and find detailed information about your car. After that, select the transmission and look for the gear ratio of the car gear there.
2. "According to the nameplate." This is the easiest and most reliable way. On the gear case can be either an engraving, or a sticker (label) containing all the information about this gear.
3. To calculate. The most reliable way, but not suitable for cars. Of course, if you are not going to disassemble the bridge.