Rear gear what. Reference information on the choice of gearbox. Application area of ​​gearboxes

Reducer for general engineering purposes. This type of equipment is an independent unit used in machine drives. His specifications meet the general requirements for different applications. Structurally, general machine-building gearboxes may differ.

Special gearboxes designed for automotive, aviation and other highly specialized industries. From the name it is clear that the units of this group must correspond to the specifics and parameters of a particular application.

Gearboxes can be classified according to the following criteria:

• By types of gears and the number of steps;
• By the location of the axes of the input / output shafts in space and relative to each other;
• According to the method of fastening.

1.1 Number of stages and arrangement of shafts

Two- and three-stage gearboxes of deployed and bifurcated circuits (in the case of two-stage models, also coaxial circuits) have a number of advantages over other types of units - first of all, this is high efficiency and load resistance. Coaxial spur gearboxes can be equipped with a low-speed stage with internal gearing. Planetary and wave units with coaxial shaft axes also provide high performance and a wide range of gear ratios.

When completing machines and mechanisms that require an intersecting arrangement of shafts, two- and three-stage bevel (bevel-cylindrical) gearboxes will be effective.

Units with worm (worm-cylindrical, cylindrical-worm) gears are characterized by a high gear ratio and low noise level. However, the efficiency of such models is lower than that of cylindrical counterparts.

The vertical arrangement of the output shafts requires less space. In mechanisms where such an arrangement is necessary, worm or bevel gearboxes are more often used. Convenience lies in the fact that the axis of the engine is in a horizontal position.

Table 1. Classification of gearboxes according to the location of the axes of the shafts

1.2 Types of gears used

1.2.1 Worm gears

Worm gearboxes are the most common type of gearboxes. The drive has compact dimensions (compared to cylindrical units). The gear ratio of a worm pair can reach 1-100 (sometimes even higher).

The potential for increasing torque with a decrease in shaft speed is higher for worm gearboxes than for equipment with other types of gears. The gear ratio of the same order can be obtained when operating a three-stage spur gearbox. In worm units, one stage is enough to solve this problem. Another advantage is the simplicity and low cost of worm gears. The use of worm gearing allows to reduce the noise level of the transmission, to ensure high smoothness.

The self-braking function is present only in worm gearboxes. Its principle is based on the braking of the driven shaft in the absence of movement on the drive shaft (worm). Self-braking in the transmission is carried out at the moment when the angle of elevation of the drive shaft is less than or equal to 3.5 degrees.

When choosing a worm gearbox, one should take into account the fact that with an increase in the gear ratio, the efficiency of the worm gear decreases. Hence - the energy loss due to the friction of the worm on the teeth of the wheel.

The resource of worm drives is, on average, 10 thousand hours.

1.2.2 Worm gear globoid

The screw of the globoid worm gear has a convex shape (in other worm gears it is cylindrical). This design feature increases torque transmission and drive power.

Globoid gearboxes are designed for use in applications requiring high reliability, no backslip and no dynamic impact on the output shaft. Most often, gearboxes of this type are used in elevator drum drives: the globoid pair is adapted to the variable loads that occur when lifting and braking the cabin, and is able to maintain normal reversibility during operation.

Table 2. Permissible loads for globoid worm gearboxes type ChG

Automotive gearbox

What is a gearbox in a car? Not everyone, even avid motorists, can give an answer to this question. In most cases, users do not pay attention to some key aspects. They only adhere to the principle: refuel, serve, drive, give to the service for repairs. So, let's see what the purpose is and what a gearbox is in a car!

A gearbox is one of the transmission units, which is used to reduce the torque received from the crankshaft. Further, the gearbox transmits torque to other transmission units, that is, the center differential.

Differential and gearbox in a car, what's the difference?

This question is often asked by motorists, so a clear line should be drawn between these two nodes. The differential is used to distribute the incoming torque between the axles, and the gearbox is used to increase / decrease the torque.

There are the following types of gearboxes:

• The front gearbox is in the front axle.
• The rear gearbox is in the rear axle.

The front gearbox is used in front-wheel drive cars, the rear - rear-wheel drive. In this case, the front gearbox in the car is integrated into the gearbox, and the second - the rear axle. An exception is all-wheel drive vehicles that have two gearboxes at the same time. In the latter case, the transmission nodes communicate with each other by cardan.

Automobile gearbox device

For familiarization, you should consider the main components of this transmission unit.

The car gearbox includes:

• The body is made of high strength steel and a number of light alloys. It is used to protect the center differential from excessive external influences.
• Fasteners - they provide a strong connection between the body and the base, seals act as seals. The latter do not allow leakage of the transmission fluid that ensures the functioning of the differential and gears.

Rear gear

• 1) Drive gear - communicates with the gearbox output shaft, transmitting torque to the driven gear.
• 2) Driven gear - after accepting the torque, it transfers it to the center differential.

It should be noted that the driven gear has large dimensions and a large number of teeth, since it is designed to receive excessively high torque from the leading one.

center differential

For example, the car turned - the outer wheel received more torque, the inner one - less. At the same time, the entire drive axle works - both wheels on the axle work together, which the automaker could not handle for a long time about 80 years ago.

Here is what it is customary to use a differential in cars:

• 1) Housing and seals - used to ensure the resistance of gears to damage.
• 2) Gears - satellites - most often there are three of them in the structure, and two of them are located parallel to each other, and the third is perpendicular. The perpendicular gear communicates with the driven. Satellites are necessary to transmit torque from the driven gear to the gears of the axle shafts.
• 3) Axle gears (wheel) - transmission of torque to the shafts of the wheel axles.
• 4) Bearings - are responsible for the rotation of the wheel shafts and the reduction of friction between the constituent elements.

Gearboxes

This group of components differs in the principle of connecting the teeth of the driving and driven gears. Through the use of various variations, there are four groups of gears in cars:

• Bevel - two bevel gears are located perpendicular to each other. This scheme is used in rear- and all-wheel drive vehicles.
• Cylindrical - two cylindrical gears communicate with each other in parallel. This scheme is used in front-wheel drive cars.
• Hypoid - gears are located in relation to each other at an angle of 45 degrees. This scheme is used in rear and all-wheel drive vehicles.
• Worm - communicating one screw with a worm driven gear.

What makes a gearbox stand out in a car?

Each car gearbox has its own characteristics, the main of which is the gear ratio, which reflects the ratio between the angular velocity of the drive / driven shafts. A high gear ratio is typical for trucks, a low ratio for cars.

It should be noted that in cars the weight of the gearbox is noticeably lower, thanks to which they develop high speeds. The gear ratio index is determined by the number of hooks of the driven gear with the leading gear in one revolution. For example, if the index is 4.8, then for a single complete revolution of the drive gear, the driven gear hits 4 whole and 0.8 times.

WITHwhat difficulties can be encountered?

Most often, the weak point of an automobile gearbox is working components, that is, those that are subject to significant wear. The main reason is increased loads and prolonged oil starvation. The last factor is associated with a shortage or complete absence of transmission fluid.

An unpleasant sound, hum, vibration and clicks in the nodes in which the gears and bearings communicate indicate a breakdown of the gearbox in the car. If the oil seals are out of order, there is a transmission fluid leak that regularly seeps through the cracks that have formed.

Damage to the hull with broken fasteners is an infrequent, but very dangerous phenomenon. It occurs as a result of a vehicle colliding with some high or sharp obstacle. In 70% of cases, after such an incident, a crack or a group of cracks forms at the hull attachment point. Immediately they will not cause any problems, but in the future they get dirt, dust, damaging the structure of the transmission fluid.

Subsequently, the raw material cannot perform the previously assigned functions of cooling and lubricating gears. This leads to overheating, wear and even breakage of the teeth. If the car gearbox housing has been damaged, a loud hum from working elements may indicate this. This significantly affects the acoustics and ride comfort. In places of damage to the body or its fasteners, an oil leak is formed.

How to solve the problem of car gearbox breakdown

Since we figured out why a gearbox is needed in a car and studied the main breakdowns, we should study ways to solve the problems that have arisen. So that the gearbox does not fail unexpectedly, it is necessary to follow the technological regulations for servicing the vehicle and do not forget to replace the transmission fluid every 100,000 km.

The second option, when it is necessary to carry out an urgent replacement of the transmission fluid, is the forced replacement of oil seals. This option is also welcomed by automotive users.

If you find any problems in the operation of the car's transmission that indicate a failure in the operation of the gearbox in the car, immediately contact the car service for a full diagnosis. This will avoid unexpected expenses and significantly reduce the cost of repairs and maintenance.

The gearbox in the car is necessary to distribute the torque transmitted from the engine between the drive wheels. Structurally, the automotive gearbox is a conical gearbox located in a separate housing.

Depending on the type of car, the gearbox is located on the front or rear axle, and all-wheel drive involves the presence of two gearboxes, since the torque in this case is distributed between all wheels.

Gear ratio of an automobile gearbox

The main characteristic of a gearbox, like any other mechanical transmission, is the gear ratio, which shows the degree of reduction in angular velocity and increase in torque transmitted to the wheels. The gear ratio directly depends on the number of teeth of the driving and driven gears. In gearboxes more teeth always has a driven gear. Due to their good performance, gears with a circular tooth are widely used in automotive gearboxes.

A gear ratio close to one has a gearbox of high-speed cars, in which the number of teeth of the driven gear is only a few units more than the leading one. An increase in the gear ratio increases the traction characteristics of the vehicle, which is especially important for special vehicles and tractors.

Features of installing gearboxes on all-wheel drive vehicles

Gearboxes with the same gear ratio must be installed on the front and rear axles of all-wheel drive vehicles, otherwise it becomes impossible to operate the machine with the center differential lock on.

Failures and repair of the gearbox

Lubrication of rotating parts in the engagement area is of great importance for ensuring the reliability of the vehicle gearbox. Lubricant leakage can lead to oil starvation, as a result of which the gear teeth will overheat and wear out intensively. Periodic control of the condition of the transmission, carried out by professional employees of the service station, will help to avoid breakdowns.

Repair of the gearbox is a work of particular complexity, as it involves a large number of adjustments and subsequent tests. One of the gears of the gearbox cannot be replaced without selection and running-in, as otherwise the required area of ​​the contact patch will not be provided. Adjustment of the gearbox is carried out by changing the gap between the end face of the gear wheel and the body of the unit.

Every car owner knows what a mechanism such as a gearbox is for and how important it is for a car. In this article, we will take a closer look at what a reducer is, what reducers are and what they are for. We will also talk about the components of the gearbox.

Story

The process of the industrial revolution was marked by the transition of wooden parts to metal ones. Wind and water-powered propellers have already created such forces that wooden details it was hard to bear. The main factor of the industrial revolution was the creation of more advanced mechanisms, the search for new energy resources. The advent of the steam engine required very large capacities. Consequently, there was a need to design metal gearboxes. By the middle of the nineteenth century, hand looms had already begun to recede far into the background and be replaced by mechanical ones with three times the productivity.

Energy began to become cheaper, which led to an increase in the speed of machine tools and strengthened their economic advantage. steam engine had enough power to run several textile looms. The machines were placed around the steam engine to increase efficiency. The steam engine unleashed the hands of manufacturing possibilities, which made it possible to build enterprises both near the water and in those places where there were coal, transport, labor and markets. Modern times have selected optimal gear designs.

Those that gave the highest economic effect gained great popularity. The middle of the 19th century was marked by the appearance of the first serial gearboxes. Well, the appearance of internal combustion engines and an electric drive a few years later marked the creation of gearboxes with specified parameters. Gear mechanisms transmitted rotational movements from high-speed engines and converted their parameters. Even the first models of electric motors and internal combustion were endowed with too much speed and torque, which, a priori, was not suitable for use in industry. Today, of course, it is difficult to find any vehicle or technological equipment that is devoid of a gear mechanism. Gearboxes are used in almost all vehicles and technological equipment. As you already understood, gears have gone through many years of development.

Reducer device

A mechanical gearbox is a mechanism that converts torque and transmits it using one or more mechanical transmissions. The gearbox is characterized by a coefficient useful action, gear ratio and transmitted power, as well as the maximum angles of the shafts that rotate at a given speed. Reducers can consist of a different number of drive and driven shafts, as well as different types of gears. Next, we will consider what types of gearboxes are based on the types of their gears.

Gearbox types

Depending on what gear the gearbox has, it will belong to one type or another. There are cylindrical, bevel, worm, planetary, wave, combined gearboxes. This classification is the main one, however, in mechanics it is also customary to distinguish between an additional classification according to the body of the product. In addition, gearboxes are often distinguished by gear ratio and distributed power.

Types of gearboxes

By type of transmission:

1. cylindrical (shafts are parallel);
2. conical (shafts intersect);
3. worm (shafts cross);
4. combined (conical-cylindrical), the shafts intersect and are parallel.

By number of steps:

1. single-stage (two shafts);
2. two-stage (three shafts);
3. three-stage.

step- one pair of gear wheels (gears), providing the conversion of rotational speed and torque.

The number of steps is equal to the number of shafts minus one!

Consider the main types of gearboxes:

Helical gearbox

The helical gearbox is used to simultaneously reduce the speed and

increasing torque. Cylindrical gearboxes are divided into horizontal single-stage and horizontal two-stage. Helical gearboxes are used for variable, constant, single direction and reversible load, both in continuous operation and in operation with periodic stops. The cylindrical gearbox has a versatile rotation of the shafts. Gearboxes of this type have a high degree of reliability and efficiency, but produce high level noise.

Worm gear

Worm gears are probably the most commonly used type of these mechanisms. It is a threaded screw (worm) meshed with a gear wheel with a special tooth profile (worm wheel). When the screw (worm) rotates, its turns, when moving, push the teeth of the worm wheel in the same direction. Thus, the dimensions of the worm gearbox are limited by the dimensions of the worm and the worm wheel. Also, these gearboxes are characterized by reduced noise and excellent smoothness.

But it also has disadvantages: heating, backlash, reduced efficiency, "self-braking".

Their application is very wide - conveyors, conveyor belts, concrete mixers, pumps. Gearboxes are used in the automotive industry, machine tool industry, even in the production of climate control and ventilation systems. different kinds reducers.

A gear motor is a symbiosis of the gearbox itself and an electric motor (sometimes also called a gear motor).

There are the following gear motors intended for use in industry: spiroid, cylindrical, worm, helical-worm, planetary, wave and special designs. Most often in the industry there are the following gear motors with a coaxial arrangement of the gearbox and motor - planetary and cylindrical. In worm geared motors, the electric motor is often located at a 90 degree angle to the output shaft.

The output shaft of the motor-reducer can be made in various variations: hollow with a slotted hole, one-sided or two-sided, conical, cylindrical or coupling.

The choice of a gearmotor should primarily be influenced by the following factors: how often the gearmotor will be started; duration of daily work; external load and shaft speed.

Reducer malfunctions

Most often, gearbox breakdowns, as an integral element of an automobile transmission, are often associated with the complete exhaustion of the resource of parts that require subsequent replacement. The main reasons contributing to the subsequent malfunctions of the gearbox rear axle are: - worn liner seals; - worn shank and differential bearings; - Failed elements of the differential; - worn or broken parts of the main pair. It is simply impossible not to notice the signs of a broken rear axle gearbox. This is an oil leak from the gearbox itself, and a characteristic howling sound that comes from this assembly during movement. All this immediately gives the cause of the breakdown. And if the leakage of transmission oil is easy enough to eliminate by installing a new shank oil seal, then the noise that a broken transmission makes is not so easy to remove.

First of all, you should check whether the noise disappears when the car is coasting. If it disappears, then the cause of the noise, of course, is in the main pair of the gearbox. If the noise and rumble have not disappeared anywhere, then most likely the reason is broken bearings.
shank or differential. Why is it so easy to diagnose such serious malfunctions? We answer. While the car is coasting, the elements of the main pair do not come into contact with force, therefore they are not able in any way to influence the appearance of a strange noise in the car.

Note that often the main pair is subject to increased wear due to low level oils. When gear parts are not sufficiently lubricated, this naturally exposes them to very high frictional and thermal overloads. And the oil level, in turn, drops sharply due to faults in the stuffing box, which becomes unusable when the shank nut is not tightened well. The next reason, leading to the replacement of the rear axle gearbox, is the increased load on the transmission, which occurs when the machine is used for a long time with a strong overload. Also, do not rule out a defect in parts from the conveyor that are installed on the rear gearbox, the cost of which is prohibitively high.

Rear axle gear adjustment

It is necessary to adjust the rear axle only in those cases when it really began to bother you with a strange hum, which is already audible at speeds from 30 km / h. The main reason for the characteristic noise in the rear axle gearbox is the constant exposure of the car to large overloads or too frequent driving with a trailer or simple mechanical damage. Therefore, do not delay with a visual diagnosis of the mechanism. Oil seals and flanges, bearings, satellites (star-shaped element in the differential) and their axles - all this will need to be removed and inspected, and in case of wear - immediately replaced. How all these parts should look in normal working condition, you will learn from the manual for your vehicle. Replacing a gearbox in a domestic car will not be expensive.

And if you have a foreign car, then it is better to study all the price lists and make inquiries in auto parts stores. Now that all the parts are in order (this was revealed during visual diagnostics), then you can assemble the gearbox. The first step is the drive gear, then the shim, flange and spacer with bearings. Next, tighten the nut with the necessary force. To do this, we take a special key with a built-in dynamometer; in the absence of one, you will have to constantly use the measuring lever. Each millimeter of lever travel will need to be accompanied by a pressure measurement with a steelyard. And this is very troublesome and long, and requires a certain accuracy and caution. The nut must be tightened by 1 Newton, during which time the flange must not move.

It must be secured with a special wrench with spacers that exactly fit the grooves of the flange in size. Then we mount the driven gear in its place in the differential case and tighten the bolts. Now we proceed to the direct adjustment of the backlash. After installing all the parts in their place, tighten all the nuts to a minimum and turn the driven gear. Next, we check it for the presence of a small backlash, shaking the gear from side to side. Remember, there should be a backlash, but not significant! This, one might say, is a spare place for heating the gearbox. So that nothing bursts when moving. On final stage we check the distance between the bolts holding the nuts that we recently tightened. The nuts must be tightened to the same distance, for this you should use a caliper. After that, we check the gear again for backlash. It's important that it stays that way. Everything, the gearbox adjustment is over.

What does a reducer do?

By itself, the word reducer in literally means downgrade. Accordingly, editors were invented in order to lower the rotational speed. In this case, the gearbox increases the power of the torque. As we already said at the beginning of the article, gearboxes are used in cars. There they are needed in order to downshift and return. This principle can be clearly seen on the example of the operation of bicycle gears, where the role of the gearbox is performed by the so-called sprockets. Note that today gearboxes are used not only in machines, but also in many engines, as well as to reduce and maintain the pressure of the working medium, including gas, steam and liquid.

What is the difference between a gearbox and a differential

This question is often asked by novice motorists. The gearbox, as we said above, is a node that increases or decreases the torque coming to it from the engine crankshaft. And the differential is a node that divides the torque coming from the gearbox between the axles (interaxle differential) or semi-axes (interaxle differential) in a certain proportion, and is also responsible for supplying more or less torque to the outer wheel when turning the car.

How to disassemble the gearbox

The gearbox housing has some features, as a result of which such a device is disassembled according to a certain scheme. This process is necessary if, for some reason, the gear unit has ceased to function normally. Some do it wrong: when the gearbox breaks, they just throw it away. However, with the right approach to this matter, the equipment can be repaired, after which the equipment will function in the same way as before.

In addition, as mentioned earlier, it is difficult to buy spare parts for a car or scooter, so you should not scatter them in vain.

• • If the gearbox housing has been disassembled for some time, then for a start it would be nice to clean it from dust and dirt;
  • Unscrew all bolts that tighten the gearbox. Take a building hair dryer. With it, warm up the device from all sides, after which wooden mallet knock on the body. This must be done until it breaks into two halves;
  • Now you can find out what caused the breakdown. Naturally there is different types gearboxes, so this should be taken into account when searching for the cause of a malfunction. The gearbox could fail for two main reasons: the input shaft or its bearing was broken, or the gear teeth were worn out. Both parts will have to be replaced if they are broken;
  • Gears and bearings should be removed to be replaced with new parts;
  • Remove the locking shield;
  • Remove the retaining ring and remove the half shaft from the cup;
  • Before starting to assemble all the parts back, you need to check their integrity;
  • When the gearbox housing is fully assembled, it can be sent to the designated place.

This mechanism can be called a key engineering device. It can be described as a mechanism for converting incoming torque and then transferring it to other systems. This definition characterizes general principle work, and in a broader sense, a gearbox can be called any converter of the direction of movement, pressure or torque.

The key features of these devices are:

• number of rotation shafts;
• transmitted power;
• appointment.

There are many types of gearboxes: mechanical, gas, water pressure reducers, turbine and others. They reduce the pressure of a liquid or gaseous medium and are able to change the direction of flow. Their work is based on a similar principle, but the internal structure and the conversion mechanism itself are different. Correct classification of gearboxes is possible only with a comprehensive consideration of all the key features of a particular type.

Classification by main features

Modern engineering standards provide for the classification of gearboxes according to the following criteria:

• the design of the transmission used;
• spatial arrangement of elements;
• constructive performance.

According to the spatial arrangement of key elements, these devices are divided into vertical gearboxes and traditional horizontal ones. The design provides for two additional types: a pure mechanical gearbox, and a gearbox with a propulsion system (reducer motor). However, the generally accepted classification of gearboxes is considered to be the type of transmission unit (transmission) used.

Gearboxes with spur and bevel gears

As a transmission unit, a cylindrical or conical gear is used. The efficiency index of this type of gearboxes is extremely high: from 80 to 98%, depending on the number of links. An important feature cylindrical and bevel gearboxes, the absence of heating elements is considered. Because of its simplicity internal device they do not need additional cooling or structural reinforcement, which explains their high reliability and ease of operation.

Here, the planetary gear acts as a working element, which converts the torque supplied to it. Planetary gears differ from standard ones in the principle of their operation: the transformation is based on rotational movement within one geometric axis. The structural features of planetary assemblies make it possible to create extremely compact gearboxes, which are widely used in various branches of instrument making and industry.

According to their characteristics, planetary gearboxes occupy an intermediate link between cylindrical and worm gears. They have a lower efficiency than cylindrical ones, but are more compact and much more durable than worm-type gearboxes. Between themselves, planetary gearboxes differ in the number of gears, their location relative to the main axis, and design.

As the main structural element here is a worm gear, which is capable of converting not only direct torque, but also angular velocity. The worm gearbox owes its name to the main screw, which carries out the transformation. It is a massive spiral screw that looks like an earthworm. The efficiency of worm gears is much lower than that of traditional cylindrical gears.

Reliability also suffers: due to complex design worm gears require careful adherence to technological standards, and under increased load they can fail. However, this type of gearbox is indispensable in cases where it is required to establish a transmission connection with perpendicularly related axes.

Structurally, the wave reducer consists of a fixed housing with internal teeth and a flexible element that is connected to the drive shaft. The flexible element has an oval shape and rotates inside the body, creating undulating disturbances.

Wave gearboxes provide a very large gear ratio - much higher than that of any other types of gearboxes. In addition, their relative simplicity and compactness allows them to be used to connect hermetically separated compartments.

General features and additional characteristics

As noted earlier, gearboxes are practically never found in their pure form. So, vertical spur gearboxes most often have several bevel gears located horizontally. Worm gears use two-stage propellers with an additional output shaft. In addition, all gearboxes can be manufactured with two design options: purely mechanical and geared motors. The latter are the most widely used and represent a single device that combines an electric motor, a gear mechanism and various auxiliary elements.

Using gearboxes of various types

Reducers act as the main element of most complex devices and assemblies. They have found application in almost all areas of industry. In heavy industry, spur and worm gearboxes are most widely used, which are used to transmit torque to a working tool.

In automobiles, the gearbox is the most common element. Gearbox, cardan shaft, brake systems, gasoline pumps and regulators - all these units use gearboxes of various types.

Gas reducers and water pressure reducers are used both in the gas production and processing industry, and at the household level (see). They allow you to control the pressure of a liquid or gas, change its direction.

Gearmotors are key elements household appliances: mixers, combines, washing machines and drills use planetary or wave geared motors to create optimal modes work.