Automatic transmissions 2

While in service the car there can be erroneous switchings. The most frequent and dangerous error of not skilled driver is moving of the handle to position "R" придвижении forward. The lever of a choice of a mode of movement is designed in such a manner that provides the resolved switchings without pressing of a clamp both at трогании from a place, and during movement. Therefore, if it is necessary for you to move the handle from position "N" to position "D" it can be made, simply having pulled it to itself. However, if you want to translate the lever from position "D" in position "L" or "R" without pressing of a clamp it will not be possible to you. It is made for prevention of breakages and transmission overloads at incorrect/choice a movement mode. Lever installation in position in which it probably to establish only with the pressed fixing button, is carried out or after a full stop (if is necessary to establish "R"), or after delay of movement to a minimum (if is necessary to establish "L").

Design feature of automatic transmissions is the equipment their special system of inclusion of lower transfer. It works by sharp or full pressing of a pedal of gas and allows to increase sharply speed of movement of a vehicle, for example, at overtaking.

Use on high speeds of three-stage automatic transmission involves some over-expenditure of fuel. Therefore the majority of modern automatic transmissions are equipped by the fourth transfer designated by symbols "0/D" or "D4". Usually use of the fourth transfer is initiated compulsorily by means of the push-button switch located on the control panel or on the handle of a choice of a mode of movement. Structurally transmission is executed in such a manner that assumes use of the fourth transfer only on the speed exceeding 40 km/hour, in the traffic conditions, not demanding big twisting moment.

In an intermediate casing, between the engine and a transmission, the hydrotransformer which carries out functions of usual coupling is established. In the course of work this knot filled трансмиссионной with a liquid, bears enough



High loadings also rotates with enough great speed. It not only transfers a twisting moment, absorbs and smoothes engine vibrations, but also puts in action the oil pump which is in the case of a transmission. The oil pump fills трансмиссионной with a liquid the hydrotransformer and creates working pressure in a control system and control. Incorrect the opinion that the car equipped with automatic transmission, it is possible to get compulsorily therefore is, without using a starter, and having dispersed it till high speed. The shesterenchatyj pump receives energy only from the engine and if the engine does not work pressure in a control system and control is not created, in what position there would be no lever of a choice of a mode of movement. Hence, compulsory rotation of the driveshaft does not oblige a transmission to work, and the engine - to rotate.

In the case of the transmission planetary mechanisms are located some, they and provide necessary transfer relations. And transfer of a twisting moment from the engine through planetary mechanisms to wheels occurs to the help of frictional disks, differential and other service devices. Management of all these devices is carried out thanking трансмиссионной liquids through a control system and control.

It is necessary to give special attention to management and control knot. This knot consists from маслосборника (the transmission pallet), шестеренчатого the pump and клапанной boxes. The klapannaja box represents system of channels with the valves located in them and плунжерами which carry out control and management functions. This device will transform speed of movement of the car, loading of the engine and degree of pressing a gas pedal to hydraulic signals. On the basis of these signals, at the expense of consecutive inclusion and an exit from a working condition of frictional blocks, transfer relations in a transmission automatically change.

The liquid used in automatic transmission, carries out the diversified functions: twisting moment transfer to the hydrotransformer from the engine in a transmission, maintenance of functioning of a control system and control, work of frictional blocks, greasing and cooling of rubbing details, etc. Therefore in an automatic transmission is applied the special high-quality mineral oil received from oil and mixed with several special additives. This oil is called as lubricant hydraulic трансмиссионной a liquid. Use of other types of oils reduces operational characteristics and frequently leads to refusal of automatic transmission. The type used трансмиссионной, as a rule, is specified a liquid on oil щупе transmissions or in the certificate of quality of the car. For maintenance of correct functioning of a transmission and its durability it is necessary to support an optimum level and to update a liquid in process of its use. Operation term трансмиссионной is specified a liquid on packing or in the quality certificate in a liquid. However operating experience shows that average periodicity of its replacement makes about 15 000 kilometres. It speaks also that second-hand cars are worn strongly out and are maintained in severe constraints. Besides, the liquid part remains in the hydrotransformer, клапанной a box, the pump and other cavities, therefore it is possible to replace only half of the used volume, i.e. there is only a liquid updating, instead of replacement. In the majority of the cars equipped with automatic transmission, the type liquid "Dexron", "Dexron-II", "Dexron-III" is used. Now in automatic transmissions on type automeans 4WD newer updating of a greasing liquid - type "Т" or "T-II" is used. The specified types трансмиссионной liquids are specially painted in different colours, type "Dexron" - red, and type "Т" - yellow. By it it is underlined what to mix them it is not recommended.

It is necessary to notice also that in the cars equipped with automatic transmissions, the block of the main transfer and a transmission can be divided, and consequently at oil replacement both compartment should be filled separately. In a compartment of the main transfer it is used usual трансмиссионное oil "SAE 85W/90" or domestic "ТАД 17", periodicity of its replacement makes 50 000 km of run.

Automatic transmissions

Improvement of operational qualities of the modern car has led to considerable complication of its design. And equipment of cars by automatic transmission has allowed to lower sharply volume of the loading assigned to the driver during movement that also was favorably reflected in a running gear, the engine and high-speed qualities of the car. Reliability and simplicity of operation have defined the further wide use of this invention. Now automatic transmissions are applied both on automobile, and on all-wheel drive cars, and even on a truck transport.

At use of a hand-operated vehicle, for maintenance of necessary speed, it is necessary for driver to use the gear change lever often.

 For this reason he is obliged to watch loading of the engine and speed of the car constantly.

Application of automatic transmission excludes necessity of constant using the switching lever. Change of speed is carried out automatically, depending on loading of the engine, speed of moving of a vehicle and desires of the driver.

Therefore, in comparison with a manual transmission, automatic transmission has following conclusive advantages:

- Increases comfort of driving of the car at the expense of clearing of the driver of control functions;

- Automatically and smoothly makes switchings, co-ordinating engine loading, speed of its movement, degree of pressing a gas pedal;

- Protects the engine and a running gear of the car from overloads;

- Supposes both manual, and automatic switching of speeds.

All variety of the automatic transmissions applied today, it is conditionally possible to divide into two types. The basic distinction of these types consists in control systems and control over transmission use. For the first type that management and control functions are carried out by the special hydraulic device is characteristic. And in the second type of function of management and control carries out

The electronic device. Components and knots of automatic transmissions of both types are almost identical.

There are some distinctions in configuration and the device of automatic transmission front-wheel and заднепрйводного the car. Automatic transmission for frontприводных cars is more compact and has in the case branch of the main transfer - differential. Despite these differences, the basic functions and a principle of action of all automatic machines are identical.

To provide movement, and also for performance of other functions, automatic transmission should be equipped by following knots: the mechanism of a choice of a mode of movement, the hydrotransformer, a transmission, in management and control knot.

The mechanism of a choice of a mode of movement represents the handle placed in salon of the car and connected with a transmission by rigid or flexible draught. By means of this lever the driver chooses a car operating mode: "forward", "back", "neutral" or "parking". On the majority of cars the way of advance consists of three stages or, it is possible to tell, three modes: a mode of low speed,



Average mode and mode of normal movement. Depending on the manufacturer these modes have different designating symbols. For example, the mode of low speed is designated by symbols "L" or "I", the average mode is designated "2", "S" or "*" more often, and a mode of normal movement - "D" or "D-3", also other symbols however are applied.

The mode of low speed is used as the first transfer to a case when the big twisting moment is required at small speed of moving. For example, трогание from a place uphill, overcoming of steep slopes on small speed, driving on the road abounding with holes and ruts.

The average mode usually has only two transfers, in other words, one switching. At the pressed pedal of gas the car moves on the second transfer, and at отпускании, after several seconds, there is a braking by the engine and switching on the first transfer that gives the chance to use less often than a brake. It is the most expedient to use this mode at driving on slippery road (snow накат, ice or a glaze ice), on road with insufficiently good covering (holes, ruts), etc.

If the lever is established in position of a normal mode of movement transmission works in a three-high-speed mode. This mode is used at movement on the road having a good covering, allowing to develop high enough speed, provides unobstructed трогание from a place in small lifting etc.

Under the lever also other symbols also are put:

"Р" - Assumes a parking of the car with the idle engine;

"R" - It is used at maneuvering;

"N" - Provides free качение the car in any direction, and also its parking with working engine.

It is necessary to notice that with a view of safety automatic transmission allows to start the engine only in position "N" or "Р".