9.5. Checks and adjustments of a mekhaniko-hydraulic part
Stall-Test
General information
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Some automobile companies consider that performance of this check is accompanied by risk of an exit of transmission out of operation owing to emergence of the raised loads of its working elements! |
Stall-Test is applied to check of serviceability of functioning of the converter of rotation (hydrotransformer) and assessment of the holding ability of brake assemblies and friction clutches of transmission assembly.
One of the defining conditions of performance of check is serviceability of a state and correctness of setup of the power unit, - check levels of cooling liquid, motive oil and ATF
Check is made at working, warmed up up to the normal working temperature, the engine and AT put on transfer, - do not forget to cock the parking brake and to prop up wheels antiretractable boots.
Conducting check of Stall-Test will require a good tachometer and the specification card of turns of the engine. Connection of a tachometer should be made strictly according to instructions of manufacturers of the device, - try to place the measuring instrument so that its dial was well looked through from the driver's place.
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Over the dial it will be reasonable to put tags of limit admissible turns, - the minimum and maximum value of turns Stall - Test - and are usually given in the specification card. |
The main lack of the described check is the potential possibility of an overheat of transmission. For this reason not all manufacturers publish specification cards of turnover of Stall-Test. Nevertheless, Stall-Test enjoys wide popularity among the experts who are engaged in recovery repair of automatic transmissions for which AT producers can issue the special bulletins made on the basis of carrying out intra-branch research works.
Order of implementation of the procedure
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- Cock the parking brake and prop up car wheels antiretractable boots.
- Warm up the engine and transmission, - temperature of ATF has to be in limits of range of 70 ÷ 80 °C.
- Connect a tachometer to the engine.
- At the cocked parking brake check turns of idling of the engine (see the Head the Current leaving and service) in position "P" of the lever of the selector.
- Transfer the selector lever to situation "R".
- The left leg firmly squeeze out a pedal of a foot brake, right accurately squeeze out the accelerator pedal to a floor, - after turns of the engine are stabilized, consider the indication of a tachometer and at once release the accelerator pedal.
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In order to avoid damage of the AT internal components the accelerator pedal should not keep pressed more than within 5 seconds! |
- Transfer the selector lever to situation "N" and let's the engine work on single turns within at least one minute for the purpose of prevention of irreversible change of structure of ATF as a result of an overheat.
- Repeat the procedure for AT D, D-HOLD and L modes.
- Determine a condition of internal knots of transmission assembly by the card given below, in case of need make the corresponding corrections.
The analysis of results of check of Stall-Test, operations procedure on elimination of malfunctions
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Result of check
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Possible reason
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Operations procedure on malfunction elimination |
| Only a few indications are underestimated for all AT modes |
- The obgonny coupling in the hydrotransformer revolves
- The managing director, or the executive valve of inclusion switching off of blocking of the hydrotransformer is faulty Ý/m
- The engine does not develop the required power
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| Indications for the D and R modes are overestimated |
- The required main pressure does not develop
- Serviceability of functioning of the obgonny O/D coupling is broken
- O/D friction clutch revolves
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- Check the main pressure
- Check a condition of the coupling
- Check a condition of a friction clutch
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| Indications for the mode "D" are overestimated |
- The required main pressure does not develop
- The friction clutch of forward transfers revolves
- Serviceability of functioning of the obgonny coupling No. 2 is broken
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- Check the main pressure
- Check a condition of a friction clutch
- Check a condition of the coupling
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| Indications for the mode "R" are overestimated |
- The required main pressure does not develop
- The friction clutch of direct perception revolves
- The brake of the modes "R" and "L" revolves
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- Check the main pressure
- Check a condition of a friction clutch
- Check a condition of brake assembly
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| Indications for the D-HOLD mode are overestimated |
- The required main pressure does not develop
- The brake of transfers from the 2nd revolves above
- The brake of the mode "2" revolves
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- Check the main pressure
- Check a condition of brake assembly
- Check a condition of brake assembly
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| Indications for the mode "L" are overestimated |
- The required main pressure does not develop
- The brake of the modes "R" and "L" revolves
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- Check the main pressure
- Check a condition of brake assembly
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Check of a delay of a response (Time-Lag-Test)
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- The transmission response to switchings of the lever of the selector at the engine working at single turns happens to the delay defined times oh.
- During this check AT response delay size on switchings of "N-D" and "N-R" is estimated.
- Perform the preparatory procedures similar Stall-Test described above for check.
- Connect a tachometer (act according to instructions of manufacturers of the device) to the engine and at the cocked parking brake check idling turns in position "P" of the lever of the selector (see the Head the Current leaving and service).
- Transfer the lever to situation "N".
- Prepare a stop watch and measure transmission response delay time for switching of the lever in situation "D".
- Return the lever to situation "N" and let's the engine work within at least one minute on single turns.
- Working in a similar manner, measure AT response delay size to switching of "N-R"
- Repeat check for each switching three times, then calculate the sensor switch arithmetic-mean values and compare them to the nominal size of the delay, for transmissions of the AW372LE type making 1.2 seconds.
- Being verified with data of the table, make the analysis of results of check, execute necessary corrections.
The analysis of results of check of Time-Lag-Test, operations procedure on elimination of malfunctions
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Result of check
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Possible reason
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Operations procedure on malfunction elimination |
| The delay of a response of switching of "N-D" is excessive |
- The required main pressure does not develop
- The friction clutch of forward transfers revolves
- The obgonny O/D coupling revolves
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- Check the main pressure
- Check a condition of a friction clutch
- Check a condition of the coupling
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| The delay of a response of switching of "N-R" is excessive |
- The required main pressure does not develop
- The friction clutch of direct perception revolves
- The brake of the L and R modes revolves
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- Check the main pressure
- Check a condition of a friction clutch
- Check a condition of brake assembly
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Check of the main pressure
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- Perform the preparatory procedures similar Stall-Test described above for check.
- Connect a tachometer (act according to instructions of manufacturers of the device) to the engine and at the cocked parking brake check idling turns in position "P" of the lever of the selector (see the Head the Current leaving and service).
- Through a special transitional nozzle connect the manometer to the service union of check of the main pressure of transmission.
- The left leg firmly squeeze out a pedal of a foot brake, transfer the selector lever to situation "D" and consider the indication of the manometer for single turns of the engine.
- Holding a brake pressed, the right leg accurately squeeze out to a floor the accelerator pedal and when turns of the engine are stabilized (turnover of Stall - Test - and), consider the indication of the manometer and at once release gas.
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In order to avoid damage of the AT internal components the accelerator pedal should not keep pressed more than within 5 seconds! |
- Transfer the selector lever to situation "N" and let's the engine work on single turns within at least one minute for the purpose of prevention of irreversible change of structure of ATF as a result of an overheat.
- Working in a similar manner, perform measurements of the main pressure for the transmission R, D-HOLD and L modes.
- Having finished check, remove the manometer and muffle the NOVA service union a stopper, having tightened it with effort of 14.7 ÷ 17.6 Nanometers.
- Compare results of the executed measurements to nominal rates.
Nominal rates of the main pressure
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Main pressure, kgf/cm2 (kPa) |
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Mode
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Engine turns |
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Idling
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Turnover of Stall - Test - and |
| "D", "D-HOLD", "L" |
3.7 ÷ 4.1 (363 ÷ 402) |
9.5 ÷ 11.0 (932 ÷ 1079) |
| "R" |
5.5 ÷ 6.1 (540 ÷ 598) |
13.2 ÷ 15.7 (1295 ÷ 1540) |
- Determine a condition of internal knots of transmission assembly by the card given below, in case of need make the corresponding corrections.
The analysis of results of check of the main pressure, operations procedure on elimination of malfunctions
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Result of check
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Possible reason
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Operations procedure on malfunction elimination |
| Indications for the D and R modes are overestimated |
- The throttle valve is jammed
- Primary valve regulator is jammed
- Adjustment of a driving cable of AT is broken
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| Indications for the D and R modes are underestimated |
- The throttle valve is jammed
- Primary valve regulator is jammed
- Pump assembly is worn-out
- Adjustment of a driving cable of AT is broken
- Leak in a hydraulic contour of a friction clutch of O/D takes place
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| Indications for the mode "D" are underestimated |
- Leak in a hydraulic contour of the 1st transfer of the mode "D" takes place
- Leak in a hydraulic contour of a friction clutch of forward transfers takes place
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- Check a condition of the corresponding valves and components
- Check a condition of a friction clutch, the corresponding valves and components
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| Indications for the mode "R" are underestimated |
- Leak in a hydraulic contour of the mode "R" takes place
- Leak in a hydraulic contour of a friction clutch of direct perception takes place
- Leak in a hydraulic contour of a brake of the L and R modes takes place
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- Check a condition of the corresponding valves and components
- Check a condition of the corresponding valves and components
- Check a condition of brake assembly, the corresponding valves and components
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Trial runs
If AT is suspected of violation of serviceability of functioning, first of all it is always necessary to try to decide on representation of nature of refusal.
At company car repair shops it is usually possible to order the card of switchings of AT where the moments of switching of transmission provided by standards at various operational parameters are specified (speed, loading, vehicle type, the direction of switching). Such additional parameters as standard installations on the operating pressure of the drive of friction clutches and brake assemblies can be specified in the most detailed maps. Besides, explanations on interpretation of the violations revealed during trial runs can be provided here. Comparison of parameters of the actual switchings taking place at trial runs with the corresponding card will help to localize possible sources of malfunctions.
There are two ways of conducting trial runs. In the first case driving the vehicle there has to be personally an owner of the car that will allow checking to make sure of adequacy of skills of its driving to requirements of the card of switchings. In the second case the pilot run is made in the safe place, free from traffic, - the skilled mechanic-driver with the assistant make detailed verification of parameters of functioning of transmission with the card of switchings. During test operation of units of transmission, the engine and systems of their management is checked. Normal work of AT depends, in many respects, on serviceability of functioning of the engine in this connection, during tests not less attention, than AT is paid to this unit.
When determining the moments of switching of transmission correctness of ratios of the operating pressure of a throttle and the centrifugal regulator at various loads of the engine is actually checked. One more factor to which special attention has to be paid during tests is absence of stress of switchings of transmission. Switchings can happen in strict accordance with requirements of the card, however violation of their smoothness, or an excessive lag effect will be powerful arguments in favor of need of performance of check of a condition of hydroaccumulators.
During the pilot run all possible high-speed and load modes have to be checked, - completeness of collected information is the key to correctness of conclusions. Special attention should be paid to behavior of the vehicle under the conditions described by the owner when violations took place, - the accuracy of definition of conditions of refusal is a fundamental factor at identification of its source.
In case of detection of the insignificant malfunctions expressed in violation of external adjustments or failure of elements which replacement does not demand dismantle of transmission from the car the corresponding procedures are made on the place. If malfunction has serious character, then performance of capital repairs of transmission is offered to the client.
During tests transmission has to be heated-up up to the normal working temperature (70 ÷ 80 °C).
Make sure of serviceability of activation of switching of kickdown in the D mode, - switchings have to take place in all provided combinations: O/D ® 3, O/D ® 2, O/D ® 1, 3 ® 2, 3 ® 1 and 2 ® 1.
In case of identification of unusual noise or vibrations try to define the nature of their emergence. The most probable sources of noise and vibration backgrounds are the hydrotransformer, driving / driveshafts and differentials. It is necessary to trace dependence of emergence of noise/vibrations on initial parameters at the movement of the car in the D mode: O/D with blocking of the hydrotransformer, O/D without blocking of the hydrotransformer, the 3rd transfer (at the included special HOLD mode).
Compare results of observations to the card of violations given below.
The analysis of results of trial runs, operations procedure on elimination of malfunctions
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Result of check
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Possible reason
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Operations procedure on malfunction elimination |
| There is no raising, or lowering switching in the range of the first or second of transfers (1-2 or 2-1) |
- It is jammed Ý/m the valve switch B
- The valve of switching 1-2 is jammed
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- Check a condition of the valve switch
- Check a condition of the valve
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| There is no raising, or lowering switching in the range of the second or third of transfers (2-3 or 3-2) |
- It is jammed Ý/m the valve switch A
- The valve of switching 2-3 is jammed
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- Check a condition of the valve switch
- Check a condition of the valve
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| There is no raising, or lowering switching in the range of the third or fourth of transfers (3-O/D or O/D-3) |
- It is jammed Ý/m the valve switch A or B
- The valve of switching 3-4 is jammed
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- Check a condition of valves switches
- Check a condition of the valve
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| Blocking of the hydrotransformer does not work |
- The managing director or the executive valve of inclusion of blocking is jammed Ý/m
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- Check a condition of valves
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| A schedule of gear shifting is broken |
- Adjustment of a driving cable of AT is broken
- The switching valves are jammed
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| Absence of stress of switchings is broken, or pro-slippings take place |
- Hydroaccumulators are jammed
- It is jammed, or the control ball of valvate assembly is lost
- Friction clutches, brake assemblies or obgonny couplings are worn-out
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- Check a state gidroak-
kumulyator
- Check existence and serviceability of functioning of control balls
- Check a condition of the corresponding components
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| There is no effect of braking by the engine |
- Friction clutches, brake assemblies or obgonny couplings are worn-out
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- Check a condition of the corresponding components
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