What Does a Transmission Mechanic Do?

The gearbox mainly refers to a car's gearbox. It is divided into two types: manual and automatic. Manual gearboxes are mainly composed of gears and shafts, which generate variable speed and torque through different gear combinations. The automatic gearbox AT is hydraulically changed. Torque device, planetary gear, hydraulic pitch control system and hydraulic control system. Variable speed and torque are achieved through the combination of hydraulic transmission and gears.

The gearbox is a very important part of the vehicle and it can be changed

(1) Change

The gearbox has roughly

More and more cars are equipped with automatic transmissions. With an automatic gearbox, people can easily drive a car between one accelerator and one brake. If the owner usually ignores the maintenance of the automatic transmission, the delicate automatic transmission is prone to failure.

The easiest thing for car owners to ignore is to choose and change the automatic transmission oil on time. In addition to normal driving, the key to maintenance is correct "oil change". It should be noted that the automatic transmission oil (ATF) specified by the manufacturer must be used, otherwise the automatic transmission will be abnormally worn. Changing the automatic transmission fluid cannot be done at a roadside shop or car beauty shop, as this operation is very strict. There are two series of international automatic transmissions. Two series of standard automatic transmission oils are used. The two cannot be interchanged and mixed, otherwise the automatic transmission will be damaged. Therefore, to change the automatic transmission oil, the owner must go to a special repair shop or a professional automatic transmission repair shop.

Under normal circumstances, the automatic transmission car should be cleaned and maintained once every 20,000 km to 25,000 km, or it should be cleaned and maintained once the gearbox slips, the water temperature is too high, the shift is slow, and the system leaks.

Precautions:

1. Master the cycle of changing the automatic transmission oil.

The internal control mechanism of the automatic gearbox is very precise and the coordination gap is small, so the oil change cycle of most automatic gearboxes is generally two years or 40,000 to 60,000 kilometers. In the process of normal use, the working temperature of the transmission oil is generally around 120 degrees Celsius, so the quality of the oil is very high, and it must be kept clean. Secondly, after using the transmission oil for a long time, grease will be generated, and oil sludge may be formed, which will increase the wear of various friction plates and components, and also affect the system oil pressure, which will affect power transmission. Third, the sludge in the dirty oil will make the valve body in each valve body move poorly, and the oil pressure control will be affected, which will cause the automatic transmission to be abnormal. Always check.

2. Replace the transmission oil properly.

The better method of oil change is dynamic oil change. Special gearbox cleaning equipment is used. During the operation of the gearbox, the old oil is fully circulated, and the new gearbox oil is added after the discharge is clean, so that the oil change rate is as high as Above 90, it guarantees good oil change effect.

3. Whether the automatic transmission oil level is normal.

The inspection method of the automatic transmission oil is different from the engine oil. The engine oil is checked in a cold state, and the transmission oil needs to be preheated to about 50 ° C, and then the gear lever is left in each gear for 2 seconds. It is placed in the parking gear at the rear. At this time, the normal oil level of the dipstick should be between the highest and the lowest lines. If it is not enough, add the same quality oil in time.

During long-term use, due to frequent gear shifts, parts and components in the gearbox will inevitably wear out and deform, which will cause difficulties in gearbox gear shifting, automatic gear shifting, and noise during operation, which will affect use. Therefore, in daily use, always check the full load operation of the gearbox, observe whether the gearbox transmission is stable, whether there are abnormal gaps and noise, and find out the reason for adjustment or repair in time. Common faults are as follows: ^[1]

The specific maintenance process of the gearbox is as follows:

1. Disintegration and preliminary inspection

It is the first step in gearbox maintenance. It completely disassembles the gearbox, including the internal oil pump, clutch, piston, planet carrier, valve body (slide valve box), differential, torque converter, etc. All dismantling is strictly Follow technical specifications and rely on a large number of special equipment and tools, otherwise it will cause parts damage. After the disintegration is completed, all parts are preliminarily tested according to standard technical data, and the fault point is found according to the actual fault of the gearbox. Visually detect the failed parts, the single-use parts and the remaining parts, and proceed to the next process.

2. Parts cleaning and testing

Parts cleaning is a very important process in the maintenance process. Cleanliness is a key factor in maintenance quality assurance. Any small impurities will have a huge impact on the working quality of the gearbox.

The cleaning process also requires several steps to complete, first the initial kerosene washing, the second ultrasonic cleaning, the third hot water cleaning, and the fourth compressed air cleaning. Cleaning requires all parts to be spotless, the surface must be free of any oil, and the oil passage must be unobstructed.

After the parts are cleaned, they are sent to the assembly station, and all the parts are tested again according to the standard to determine all the materials that need to be repaired and ready to be assembled.

3.Valve body cleaning and maintenance

This process is performed at the same time as the previous step. The valve body (sliding valve box) is the core component of the automatic transmission. The casting is precise and requires very professional personnel to operate this step. As a professional maintenance, all the valve bodies need to be disassembled, cleaned thoroughly after disassembly, and then check all the sliding valve and valve body for wear according to the actual situation. After assembly, the pressure test is strictly compared with the standard data. Only the valve body that meets the standard data range can enter the assembly station.

In addition, this station also needs to perform functional tests on electrical components such as solenoid valves, various sensors, wiring harnesses, and pressure switches. Only parts that pass the rigorous test can enter the next station.

4.Small assembly

The small assembly assembly is the re-inspection and adjustment of the internal components during the repair of the gearbox. It is the previous process of assembling the assembly. Its operations include:

Assembly and inspection of oil pumps

Clutch assembly and clearance adjustment detection

Assembly adjustment test of shift mechanism

Valve body assembly inspection

Differential assembly adjustment test

Assembly and adjustment of planetary gear mechanism

Seal holding pressure test

5.Assembly assembly

Assembly assembly is the last process of assembly and needs to be completed in a special working environment. The position, clearance, pre-tensioning force, etc. of all components must be operated strictly in accordance with technical specifications. After the assembly is completed, a static pressure test is performed, and the next process can be entered after the technical standards are reached.

6.Assembly dynamic test

The assembly dynamic test is a dynamic test of the transmission through a test bench that simulates the work of a car

Through the simulation test, various working performances of the gearbox can be detected, such as whether the various oil pressure data meets the technical specifications; whether the shift-in, up-shift, and down-shift are smooth; whether the lock-up clutch combined with the release meets the requirements; whether the predetermined speed is reached; Whether the cooling flow of the gearbox reaches the standard range; whether the noise of the gearbox operation meets the requirements and so on. All test data must be recorded and compared with standards, and the products can be delivered to customers for use only after meeting the requirements.