Checks and adjustments of a mekhaniko-hydraulic part

Stall-Test

General information

Stall-Test is applied to check of serviceability of functioning of the converter of rotation (hydrotransformer) and an assessment of holding ability of brake assemblies and friction clutches of transmission assembly.

One of defining conditions of performance of check is serviceability of a condition and correctness of setup of the power unit, - check levels of cooling liquid, impellent oil and ATF

Check is made at working, heated-up to normal working temperature, the engine and AT put on transfer, - do not forget to cock the parking brake and to prop up wheels protivootkatny boots.

For carrying out check of Stall-Test the good tachometer and the spetsifikatsionny card of turns of the engine is required. Connection of a tachometer should be made strictly according to instructions of manufacturers of the device, - try to place a measuring instrument so that its dial was well looked through from a driver's place.

The main lack of described check is potential possibility of an overheat of transmission. For this reason not all manufacturers publish spetsifikatsionny cards of turns of Stall-Test. Nevertheless, Stall-Test uses wide popularity among the experts who are engaged in regenerative repair of automatic transmissions for whom producers of AT can issue the special bulletins made on the basis of carrying out intra branch research works.

Order of performance of procedure

Check of a delay of a response (Time-Lag-Test)

Check of the main pressure

Trial runs

If AT is suspected of violation of serviceability of functioning, first of all always it is necessary to try to decide on representation of nature of refusal.

At firm 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 are specified at various operational parameters (speed, loading, vehicle type, the switching direction). In the most detailed maps such additional parameters, as standard installations on operating pressure of a drive of friction clutches and brake assemblies can be specified. Besides, here explanations on interpretation of violations revealed during trial runs can be provided. Comparison of parameters of the actual switchings which were taking place at trial runs, with the corresponding card will help to localize possible sources of malfunctions.

There are two ways of carrying out trial runs. In the first case at a wheel of a vehicle there should 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 test arrival is made in free from traffic a safe place, - 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, this unit during tests is given not less attention, than AT.

At definition of the moments of switching of transmission correctness of ratios of operating pressure of a throttle and a centrifugal regulator is actually checked at various loads of the engine. One more factor to which it should be paid special attention during tests, absence of stress of switchings of transmission is. Switchings can occur in strict accordance with card requirements, 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 test arrival all possible high-speed and loading modes should be checked, - completeness of collected information is guarantee of correctness of conclusions. It is necessary to give special attention to behavior of a vehicle under the conditions described by the owner when violations took place, - 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 transmission dismantle from the car, the corresponding procedures are made on a place. If malfunction has serious character, performance of major maintenance of transmission is offered to the client.

During tests transmission should be heated-up to normal working temperature (70 ÷ 80 ° C).

Make sure of serviceability of activation of switching of kickdown in a mode "D", - switchings should 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 vibrating backgrounds are the hydrotransformer, driving / driveshafts and differentials. It is necessary to trace dependence of emergence of noise/vibrations on initial parameters at car movement in a mode "D": O/D with blocking of the hydrotransformer, O/D without hydrotransformer blocking, the 3rd transfer (at the included special HOLD mode).

Compare results of supervision to the card of violations given below.

The analysis of results of trial runs, operations procedure on elimination of malfunctions