9.2. Automatic Transmissions (AT)AT F3A21 design
Design of AT of the F4A20 series (F4A22 and F4A23)
Scheme of functioning of the planetary transmission
Scheme of functioning of the planetary transfer case
1 — the Output shaft of the transmission
4 — the Shaft of the drive of forward wheels
For a complete set of the models considered in the present manual 4-staged AT of the F3A20 (F3A21) and F4A20 series (F4A22, F4A23, F4A33 and F4A51) are used. All transmissions are equipped with the blocked rotation converter. The converter provides direct coupling between the engine and driving wheels of the car. Transmissions can have electronic control, - in this case the onboard processor makes switching of a box to the raising or lowering transfer, based on the analysis of information arriving from three electromagnetic blocks installed on the case of valvate assembly.
In view of complexity of a design of AT, absence on free sale of replaceable internal components, and also need of use of the special equipment, authors of the present manual do not recommend to owners of cars to carry out capital repairs of transmission by own forces. In the present Chapter only procedures of diagnostics of the general refusals of AT, its routine maintenance, main adjustments, removals and installations are considered.
Sometimes, in case of serious breakage, it is more reasonable and simpler to replace transmission, than to spend time and funds for restoration of the failed assembly. Regardless of the chosen way of introduction of the refused AT to action, independent performance of its removal and installation will help to cut down substantially expenses (before make sure that transmission really needs recovery repair).
Towage of the car from the refused AT has to be made with a speed not higher than 50 km/h (30 miles/h) and on distance no more than 80 km (50 miles)!
Design and principle of functioning
Generally automatic transmission consists of the converter of rotation, distributing assembly and differential. Transmission of F3A21 represents 3-staged AT with mechanical control. The F4A20 series differs in a 4-staged design and has electronic control.
The internal device of transmissions of both series is almost identical. The main difference consists in use of the raising 4th transfer on assemblies of the F4A20 series. Transmission consists of the 3-element converter of rotation with the operating regulator (F3A20 series), converter clutch couplings (F4A20 series), one planetary assembly, one brake tape and three (F3A20 series) or four (F4A20 series) of multidisk clutch couplings.
Planetary assembly of transfers consists of two planetary rows. A planetary row with frictional elements of management (the blocking coupling and a brake) is a part of the transfer case. The electronic block operates work of all transmission. Switching of the high-speed modes is made by means of the car installed in salon selector growling. The selector by means of a cable is connected to valvate assembly, and with its help it is possible to set the range of the used transfers. Besides the selector in salon for a task of the special modes of functioning of transmission one or several switches are provided.
For prevention of breakages of AT at the wrong choice of high-speed range, for example, movement from "D" the clamp is provided in "R" on the lever of the selector, - "dangerous" switchings can be carried out only at the pressed clamp button. Application of a clamp allows to avoid a situation when on imprudence one of ranges of the movement can be included and the car will begin to move uncontrolledly. The lever of the selector can be installed in one of six fixed provisions: "Р", "R", "D", "N", "2" and "L", appointment of each of which is considered below.
Is chosen at the parking of the car. In this situation, in transmission all elements of management are switched off, and its output shaft is blocked, - the movement of the car is impossible. It is necessary to transfer the selector to situation "P" only after a full stop of the vehicle.
Transfer of the selector to situation "P" during the movement can lead to a transmission exit out of operation!
Backing. It is possible to transfer the selector to a R position only after a full stop of the vehicle.
Turning on of the reverse gear during the movement of the car can lead to a transmission exit out of operation!
Neutral situation. In a box all elements of management are switched off that provides lack of rigid kinematic communication between her leader and conducted by shaft. The mechanism of blocking of an output shaft at the same time is switched off, i.e. the car can freely move. It is not recommended to switch transmission to situation "N" at the movement by a setup.
Do not switch off ignition at the movement under a bias at all!
Main mode of the movement. Provides automatic switching with the first on the fourth transfer. It is recommended at the movement in normal conditions.
The movement on the first three transfers is authorized. It is recommended to use at movement along the hilly road or in the conditions of frequent stops (an intense city cycle).
14 The movement only on the first and second transfers is authorized. It is recommended to use, for example, on twisting mountain roads. Switching to the third and fourth transfers is forbidden. On this range the braking mode is effectively used by the engine.
The movement only on the first transfer is authorized. This range allows to realize as much as possible the braking mode the engine. It is recommended at the movement on abrupt descents, rises and off road terrain.
OD mode (F4A20 series transmission)
Permission to use of the fourth, raising, transfers is carried out by means of the special OD button. If the button is in the drowned state and the lever is installed in situation "D", then switching to the raising transfer is authorized. Otherwise inclusion of the fourth (raising) transfer is forbidden. The condition of a control system in this case is determined by the control lamp "O/D OFF". In case of permission of the raising transfer the indicator does not burn, at the ban, - burns. The mode is used at the movement with a constant speed on direct sections of the highway. It is necessary to avoid use of the OD mode in city conditions, especially in winter season when braking by the engine gains the vital value. It is also not necessary to include the mode of the raising transfer at full load of the car.
Special programs (if are provided)
On cars with AT two control modes are put by gear shifting: "economic" (NORMAL) and "sports" (POWER). The choice is carried out by means of the special switch which is built in in the central console of the car.
Economy mode (NORMAL)
In this mode the minimum consumption of fuel takes place. Gear shiftings happen in the middle of the corresponding ranges of the engine, the nature of the movement of the car quiet, smooth.
Sports mode (POWER)
At inclusion of this mode on the panel of priors the control lamp of "ECT POWER" lights up. In this mode there is the maximum selection of engine capacity, - switching of a box is made in the upper bound of the corresponding ranges of turns of the engine. Acceleration performance of the car substantially increases, fuel consumption, respectively, increases.
Three planetary rows, three blocking couplings, four brakes and three couplings of a free wheeling are a part of the planetary transmission.
Power from the engine via the hydrotransformer is transferred to an entrance shaft of the planetary transmission.
Gear shifting is carried out by inclusion of a certain combination of brakes and couplings of a free wheeling therefore the frequency of rotation of an output shaft changes.
Elements of the planetary transmission
The function chart of planetary assembly of the automatic transmission is submitted on an illustration.
The blocking coupling of the raising planetary row (C0) connects and solar drove also a solar wheel of the raising planetary row.
The brake of the raising planetary row (B0) stops a solar wheel of the raising planetary row.
The coupling No. 1 of a free wheeling (F1) at the included brake of the second transfer forbids rotation counterclockwise of solar gear wheels of forward and back planetary ranks.
The coupling of the forward course (C1) connects an entrance shaft and an epicycle of a forward planetary row.
The brake of the second transfer (B2) stops an external ring of the coupling of a free wheeling No. 1, forbidding thereby rotation of solar gear wheels of forward and back planetary ranks counterclockwise.
The brake of the 1st transfer and backing (B3) stops drove a back planetary row.
The coupling of a free wheeling No. 2 (F2) forbids rotation drove a back planetary row counterclockwise.
The coupling of direct transfer (C2) connects an entrance shaft and solar gear wheels of forward and back planetary ranks.
The brake of providing the mode of braking with the engine on the second transfer (B1) stops rotation of solar gear wheels of forward and back planetary ranks.
The coupling of a free wheeling of the raising planetary row (F0) at start of the engine connects a solar gear wheel and drove the raising planetary row.
Planetary transfer case
The scheme of functioning of the planetary transfer case is submitted on an illustration.
The transfer case contains one planetary row, two blocking couplings and one brake.
Elements of the planetary transfer case of transfers:
The coupling of the forward course (SZ) connects an output shaft of the transmission to the satellite of a planetary number of the transfer case of transfers.
The coupling of direct transfer (C4) connects a shaft of the drive of back wheels and the leading asterisk of chain transfer of the drive of forward wheels.
The coupling of the raising transfer (B4) stops rotation of an epicycle of a planetary number of the transfer case.
Device of a hydraulic part of a control system
Hydraulic part of a control system consists of the oil pump, valvate assembly, electromagnetic valves, couplings and brakes, and also the channels connecting among themselves the listed elements. Pressure of working liquid created by the pump is used for management of frictional elements of transmission, feed of the hydrotransformer and lubricant. In valvate assembly three electromagnetic valves of switching are installed. With their help the electronic block exercises control of gear shifting and blocking of the hydrotransformer.
Electric part of a control system (F4A20 series transmission)
Electric part operates gear shifting in the transmission and the transfer case, and also the blocking coupling of the hydrotransformer. It consists of three parts: the sensors of speed of the movement of the car (VSS), the sensor of provision of a butterfly valve (TPS) and other information sensors tracing parameters of a condition of transmission and transferring data to an electronic control unit; an electronic control unit which on the basis of the analysis of the data arriving to it defines the switching moments in the transmission and the transfer case, and also operates the blocking coupling of the hydrotransformer; and the executive part consisting of four electromagnetic valves.