It is a rather complex technical unit. It includes several hundred components that interact with each other and ensure smooth and comfortable acceleration of the car in various driving modes. One such element is a temperature sensor. Read about why it is needed and how it works in this article.
Strict necessity
The automatic transmission is designed in such a way that almost all manipulations in it occur with the help of oil injected under pressure. The pressure is pumped up by a special oil pump, which in its structure and design resembles an engine cooling pump and works in a similar way.
The oil circulates at incredible speed. To at least roughly imagine what this speed is, you need to open a water tap and in your imagination increase the pressure and pressure of this water several tens of times.
An inexperienced motorist, and indeed a person who does not repair automatic transmissions on his own, will have a logical question: why is such high pressure needed, and why is it so useful when operating an automatic transmission?
In fact, all movements of the clutches, which are similar in principle to the gear shafts of mechanical transmissions, are carried out precisely due to a powerful jet of oil. This oil flows through a system of automatically shutting channels called solenoids. Depending on the path for oil provided by the solenoid, the clutches move under pressure in such a way that they eventually form packages that connect the engine and wheels in a certain way.
When an automatic transmission is operating, the oil inevitably heats up: this is caused simultaneously by high pressure in the oil channels and strong friction achieved when connecting the clutches and their synchronous movement. The temperature sensor allows the automatic transmission control unit to receive data about the state of the technical fluid in the crankcase and how efficient the entire functional unit is.
How it works?
Generally speaking, the meaning of the role played by the automatic transmission temperature sensor is quite transparent. If for some reason the liquid temperature exceeds the programmed threshold, the control unit makes a chain of decisions. These solutions are aimed at informing the driver that a problem has arisen and developing actions to restore the functionality of the automatic transmission and its rehabilitation.
For example, on most cars the dashboard is equipped with an automatic transmission overheating indicator. As soon as the sensor is triggered and gives a signal to the control unit, it displays information on the instrument panel, and the driver already understands that something has gone wrong.
On the most modern transmission models, a special algorithm has been implemented, which in emergency cases allows you to bring the transmission back to normal. For example, gears begin to shift more smoothly, and the maximum speed of the car decreases. On top of that, the engine operating mode becomes such that the transmission is not subjected to excessive loads.
For many, it remains unclear where such a sensor is located and what it looks like. In appearance, such a device is a small metal cylinder. This cylinder has several wires at the output that are connected to the power source and the control unit, or rather, its input radio channels. The device is located in the transmission crankcase - the largest amount of oil is located there, and controlling its temperature in this way is much easier and more rational.
Summary
Modern automatic transmissions are necessarily equipped with such a useful device as an automatic transmission oil temperature sensor. Thanks to this, the risk of causing the transmission to fail is greatly reduced, and the service life of all functional elements increases significantly.
For full operation of the vehicle, a number of working lubricating fluids are used, which ensure the proper operation of all vehicle systems. One of such systems is the transmission, for which specialized automotive oil is used. It is used to lubricate gears found in manual transmissions, as well as steering mechanisms, drive axles and transfer cases.
Today there are two types of “transmission”:
- for use in manual transmissions (manual transmissions);
- for front- and rear-wheel drive vehicles with automatic transmission (automatic transmission). This type of oil is also used for power steering (power steering).
The second category of lubricating fluids allows you to remove mechanical stress, effectively lubricates elements, removes heat, corrosion products and micro-abrasive particles in the most worn parts. Oils for automatic transmissions transmit mechanical energy to all hydromechanical transmission complexes. This category of lubricants is subject to the most stringent requirements (when compared with oils for manual transmissions).
Mineral, synthetic and semi-synthetic materials are used as the basis for gear oils. Just like for motor oil, when choosing a “transmission”, the classifications of petroleum products are taken into account, based on which indicators such as viscosity and quality of the lubricant can be determined. Let's take a closer look at these standards.
SAE viscosity classification of transmission oil
The SAE index, which indicates the viscosity of transmission oil, was developed by the American Society of Engineers. This standard has become widespread throughout the world and today the SAE J306 specification is used to determine the viscosity classification of motor oil for drive axles and manual transmissions. This qualification also determines the temperature range at which the use of a particular lubricant is permissible.
The lowest and highest temperature at which a car can be operated has its own limit, which is estimated:
- at the temperature at which the Brookfield viscosity of the liquid reaches 150,000 cP (centipoise);
- by the temperature at which the kinematic viscosity of the “transmission” is determined at a temperature of 100 degrees.
Thanks to this, it is possible to determine the load (approximate) that the protective oil film can handle.
According to SAE standards, transmission oils are divided into categories similar to motor lubricants:
- winter (W, Winter): 70w, 75w, 80w, 85w;
- summer (without index): 80, 85, 140, 250.
All-season fluids have both markings, for example, SAE 75w-85. These oils can be used throughout the year. As you can see, in this regard, “transmission oils” are similar to motor oils, but this does not mean that these petroleum products are used under the same conditions and have the same performance. The same applies to questions about whether it is possible to pour the “transmission” into the engine and vice versa. Motor oil can be used for gearboxes, but transmission fluid cannot be poured into the engine.
Table of ambient temperature ranges in which transmission oils can be used. The most commonly used types of oils are indicated
| Minimum temperature at which lubrication of components is ensured, °C | SAE class | Maximum ambient temperature, °C |
| -40 | 75W-80 | 35 |
| -40 | 75W-90 | 35 |
| -26 | 80W-85 | 35 |
| -26 | 80W-90 | 35 |
| -12 | 85W-90 | 45 |
API viscosity classification of gear oil
According to the API GL system, oils are divided into quality classes. The main features of the classification are the design and operating conditions of the transmission, additional features are the content of anti-wear and extreme pressure additives.
The classification is described in the API document “Designation of operating lubricating oils for manual transmissions and axles. API Publication 1560, February 1976." (API Publication 1560, Lubricant Service Design for Automotive Manual Transmissions and Axles, February 1976). API quality classes:
GL-1
- Oils for gears operating in light conditions.
- Consist of base oils without additives. Sometimes antioxidant additives, corrosion inhibitors, light depressants and anti-foam additives are added in small quantities.
- Designed for spiral-bevel, worm gears and manual transmissions (without synchronizers) of trucks and agricultural machines.
GL-2
- Contains anti-wear additives.
- Designed for worm gears of vehicles.
- Typically used to lubricate transmissions of tractors and agricultural machines.
GL-3
- Oils for gears operating in medium-heavy conditions.
- Contains up to 2.7% anti-wear additives.
- Designed for lubrication of bevel and other gears of trucks.
- Not suitable for hypoid gears.
GL-4
- Oils for gears operating under conditions of varying severity - from light to heavy.
- Contains 4.0% effective extreme pressure additives.
- Designed for bevel and hypoid gears with small axle displacements, for truck gearboxes, and for drive axle units.
- API GL-4 oils are intended for non-synchronized transmissions of North American trucks, tractors and buses (commercial vehicles), for final drives and other transmissions of all motor vehicles. Currently, these oils are also the main ones for synchronized gears, especially in Europe. In this case, the label or data sheet of the oil must contain inscriptions about this purpose and confirmation of compliance with the requirements of the machine manufacturers.
GL-5
- Oils for the most heavily loaded gears operating in harsh conditions.
- Contains up to 6.5% effective extreme pressure and other multifunctional additives.
- The main purpose is for hypoid gears with significant axial displacement.
- They are used as universal oils for all other mechanical transmission units (except for the gearbox).
- For synchronized manual transmissions, only oils that have special confirmation of compliance with the requirements of vehicle manufacturers are used.
- Can be used for limited slip differentials if they meet MIL-L-2105D (US) or ZF TE-ML-05 (Europe) specifications. Then the class designation has additional characters, for example, API GL-5+ or API GL-5 SL.
- Oils for the most heavily loaded gears operating under very difficult conditions (high sliding speeds and significant shock loads).
- Contains up to 10% highly effective extreme pressure additives.
- Designed for hypoid gears with significant axle displacement.
- Correspond to the highest level of performance properties.
- Currently, GL-6 is no longer used as API GL-5 is considered to satisfy the most stringent requirements quite well.
New API classes
MT-1
- Oils for highly loaded units.
- Designed for non-synchronized manual transmissions of powerful commercial vehicles (tractors and buses).
- Equivalent to API GL-5 oils, but have increased thermal stability.
PG-2 (project)
- Oils for drive axle transmissions of powerful commercial vehicles (tractors and buses) and mobile equipment.
- Equivalent to API GL-5 oils, but with increased thermal stability and improved elastomer compatibility.
Classification of transmission oil viscosity according to GOST
The Russian Federation has its own classification, which is also used when determining the characteristics of transmission oil, namely GOST 17479.2-85, this standard was introduced for both motor oils and “transmission oils”. It includes viscosity criteria, which are divided into four classes: 9, 12, 18 and 34. It also includes an indicator of the quality of the petroleum product, which is divided into five groups; in gradation, each group corresponds to the API quality standard, for example, TM-1 (transmission oil) equals GL-1, TM-2 equals GL-2, and so on.
Thus, if we have the marking TM-5-18, then the last digit will indicate the kinematic viscosity of the liquid.
According to GOST 23652-79, there are the following brands of transmission lubricating fluids based on viscosity indicators:
- TEP-15 - are made on the basis of an extract of residual and distillation oils. They have anti-wear and depressant additives.
- TSp-10 - contain extreme pressure, depressant and anti-foam additives. Such oils are used for heavily loaded gears.
- Tap-15B - is produced by mixing extracts of residual phenolic oils with distillate oils. Contains extreme pressure and depressant additives.
- TSp-15K - contains extreme pressure, anti-wear, depressant and anti-foam additives. Applicable for heavy-duty vehicles, for example, KAMAZ vehicles.
- TSp-14 gip - includes extreme pressure, antioxidant, depressant and anti-foam additives. Used for hypoid transmissions of trucks.
- TAD-17i are universal liquids that are made on a mineral basis. Contains multifunctional sulfur-phosphorus-containing, depressant and anti-foam additives.
In addition to viscosity, when choosing a lubricant, you need to pay attention to the classification of performance characteristics (API - USA or ZF - European standard), as well as the density of the transmission oil. For example, for TEP-15 oil, the density at 20 degrees will be no more than 0.950 g/cm3.
All these properties may change after a long period of storage of the gearbox lubricant. Therefore, it is necessary to remember such points as: the expiration date of gear oil.
Storage conditions for transmission oil
Gearbox lubricants have a warranty period of 5 years, and in some cases 3 years. After this period, the additives contained in the liquid lose their properties and, accordingly, such expired oil will not meet the necessary requirements.
It is worth noting that the period of 3-5 years indicates the shelf life of automobile oil in unopened containers. If you have already opened the bottle, the shelf life of the liquid will depend on many conditions. In order for the composition to remain effective longer, you must adhere to the following recommendations:
- avoid temperature changes; the liquid must be stored at a constant temperature not exceeding 20 degrees;
- the oil should be stored in a well-ventilated area, away from direct sunlight;
- It is not recommended to pour the lubricant into another container; it is better to store it in the factory canister with a tightly closed lid;
- Do not freeze the transmission under any circumstances.
If these conditions are met, the oil will be stored for the entire stated period.
Some car enthusiasts “revive” expired oil with special additives. This is not recommended, since “live” additives may remain in the liquid and with such mixing their quantity will change, which, in turn, will no longer meet the standards. In addition, new components can enter into a chemical reaction with old additives, as a result of which their properties will be unpredictable.
Many people mistakenly believe that if the “transmission” has changed its color, then this is the main sign that the fluid is unsuitable. It is not always so. The fact is that during the production process the main parameter is the lubricating characteristics of the composition, so some deviation in color or smell is acceptable. However, if not only the color has changed, but also a dark crystalline precipitate has appeared, and the oil itself has become cloudy, then such a product cannot be poured.
It is also worth saying that storing transmission or motor oil in a barrel or car system are two different things. In the second case, the lubricant is constantly in contact with the environment, as a result of which oxidation processes occur and various deposits appear. Therefore, even if you pour new oil into a car without mileage, this does not mean that you can change it after 5 years. A scheduled gearbox oil change depends on operating conditions, but experts recommend changing the fluid every 70,000 km during normal operation of the system and after 25 000 km when driving in special conditions (heat, cold, full load, etc.).
In custody
Some brands of cars do not provide for scheduled replacement of the transmission, but, nevertheless, it is recommended to check the fluid level weekly.
The gearbox contains numerous moving parts that, when rubbing against each other, can generate large amounts of thermal energy. To cool the moving mechanisms of an automatic transmission, a special transmission oil is used, which simultaneously cools and lubricates the moving elements. Problems with the lubrication system invariably lead to an increase in the operating temperature of the automatic transmission. In this case, the coolant temperature can reach 120 degrees or more, at which the lubricant loses its properties and increased wear of the gearbox begins.
Consequences of automatic transmission overheating
Automatic transmission overheating leads to failure of clutches and other moving elements. In some cases, even 10 - 20 minutes of operation of the gearbox in overheating mode is enough, which leads to serious damage and the need for major repairs. That is why at the first signs of overheating, as a rule, this is indicated by sensors built into the gearbox, it is necessary to turn off the car and transport it to a service station on a tow truck. This way you can avoid significant problems caused by prolonged operation of the gearbox at elevated temperatures. During long-term operation of the gearbox with an increased operating temperature, problems may arise with the geometry of the hydraulic plate and control unit. It should be remembered that a control unit that has failed due to overheating cannot be repaired and therefore requires an expensive replacement. It is for this reason that the car owner needs to closely monitor the condition of the gearbox and, when the first reports of oil overheating in the automatic transmission appear, contact a specialized service center.
It also happens - when there is severe overheating, the torque converter turns blue and the ventilation tubes melt
Causes of overheating
Let's describe automatic transmission overheating causes that need to be eliminated. The most common cause of transmission overheating is insufficient pressure in the cooling system. This happens due to insufficient oil level or problems with. The car owner needs to closely monitor the oil level in the gearbox and, if necessary, replace it.
Cooling problems may occur due to improper operation of the solenoids. The solenoids are located in the hydroblog and actually act as electric valves in the lubrication and cooling system. If necessary, a corresponding signal is sent to the solenoid, the valve opens and oil flows to the moving elements, lubricating and cooling them.
Also, overheating of the gearbox can be caused by problems with the oil heat exchanger. This quite often happens when the heat exchanger is contaminated, the honeycombs of which are clogged with wear products, which does not allow the hot oil from the gearbox to effectively cool in the heat exchanger, which leads to an inevitable increase in temperature.
Signs of automatic transmission overheating - Video
How to eliminate automatic transmission overheating?
Repairing a gearbox for problems with overheating involves diagnosing, which allows you to determine the cause of the temperature increase. An experienced technician will be able to quickly localize the problem and repair the gearbox in the shortest possible time. In most cases, to eliminate overheating of the automatic transmission, it is necessary to clean the valve body and external heat exchanger. This work presents a certain complexity, since it is necessary to dismantle the hydraulic unit and remove all the pipes that lead from the box to the heat exchanger. Cleaning can be carried out using modern technological means, which allows us to ensure the maximum quality of the repairs carried out. All this allows you to eliminate the problem of overheating.
Cleaning the valve body when overheated
14.APPLICATIONS
Appendix A. Gearbox
A.1 Gearbox maintenance
ZF service specialists are at your disposal to carry out maintenance work on the gearbox and solve any problems that may arise.
Good maintenance means reliable transmission operation. It is particularly important that the necessary maintenance work is carried out correctly.
Danger to the environment!Lubricants and cleaning agents must not enter the ground, groundwater or sewer system. Ask your local environmental authority for safety data sheets for the products in question and follow them. Collect used oil in containers of sufficient size. Dispose of used oil, dirty filters, lubricants and cleaning agents in accordance with environmental regulations. When working with lubricants and cleaning agents, follow the manufacturer's instructions.
To fill the Ecomat gearbox, oils must be used in accordance with the ZF lubricant specification TE-ML 14. The volume and brand of oils being poured are indicated in the Chemmotological Card.
Oil level control
Maintaining the correct oil level is critical. Too little oil leads to damage to the gearbox and incorrect operation, to partial or complete failure of the retarder, i.e. to reduced or zero braking force. Too much oil will cause the transmission to overheat.
Oil level monitoring must be carried out together with maintenance at a service center at intervals of 1/4 of a year. Checking the oil level must be carried out with the vehicle parked horizontally and at operating temperature of the gearbox. It is necessary to carry out constant visual monitoring for gearbox leaks. In exceptional cases, monitoring on a “cold” gearbox is necessary (measuring an approximate value). Then always carry out the test at operating temperature.
Control at operating temperature
The determining factor is level control at a transmission oil temperature of 80-90°C. To do this, you need to place the vehicle in a horizontal position and switch the controller to the neutral position. In this case, the engine should operate at idle speed.
CAREFULLY! The idle speed should be set from 500 to 700 min -1.
The oil level should be in the warm range after about two minutes.
Measuring the reference value
This is an oil level measurement taken when the transmission oil is cold. Such control is carried out in the following exceptional cases:
When putting the gearbox into operation for the first time;
After a long period of inactivity or when accepting someone else’s vehicle;
After repairing the gearbox in the vehicle: for example, removing the oil pan, hydraulic control, oil cooling heat exchanger, etc.;
After changing the oil or filter.
Measuring the reference value consists of two steps:
Control before starting the engine;
Check after engine start.
After this, check at operating temperature.
Check before starting the engine
The oil level must be within the range indicated by “n engine”. = 0" or higher.
NOTICE!
If the level is higher, do not drain the oil.
Check after engine start
The engine should be idled for 3 to 5 minutes (controller in neutral). Then measure the oil level. The oil level must be in the range indicated 30 °C
Possibility of heating transmission oil
During normal operation of a vehicle with brake-retarder cycles, transmission oil can heat up to an operating temperature of 80-90 ° C in the oil bath provided to control the oil level.
If normal operation of the vehicle is not possible (winter season), then the transmission oil should be warmed up as follows:
Apply the parking brake.
Select the gear ratio change range "D".
Apply the brake mechanism of the service brake system.
If necessary, start the engine several times for 15 to 20 seconds at partial load at a speed of 1200 to 1500 rpm.
Maximum permissible oil temperaturein front of the heat exchanger is 110°C (constant). After each heating phase, start the engine for 15 to 30 seconds with the gearbox in neutral at a speed of 1500 to 2000 rpm.
After reaching operating temperatureSet the gearbox to neutral and run the engine at idle speed for 2-3 minutes.
Then check the oil level according to paragraph 3.3.1.
Oil change intervals
The frequency of oil changes is determined according to the ZF lubricant specification TE-ML 14 and is indicated in the vehicle's chemotological chart.
ATTENTION! The oil filter must be renewed at every oil change.
When converting from a mineral based oil to a partially synthetic oil, hydrocracked or synthetic ATF, it is recommended to perform an unscheduled oil change midway through the oil change interval.
Oil drain
Drain the oil only at operating temperature and for at least 10 minutes after stopping the engine.
The engine is at rest.
Unscrew the screw plug (1) (Fig. 14.1) of the oil drain hole and drain the oil.
Remove the filter cover (2).
Renew the filter element, copper rings and O-rings.
Oil refill
Install filter cover 2 (Fig. 14.1) (screw tightening torque 25 Nm).
Screw in the oil drain plug (1) (tightening torque 50 Nm).
Pull out the oil level indicator (3) (Fig. 14.2).
Add oil.
Check oil level.
Rice. 14.1 Draining the oil.
Monitoring load sensor settings
The load cell setting must be checked after maintenance work on the gearbox or engine, during sudden shifts and at least every 3 months.
The condition for carrying out the control is the correct tuning of the engine. Inspection can be carried out using markings on the front or top of the housing.
To carry out control it is necessary:
Turn off the engine;
Apply the parking brake;
Slowly depress the accelerator pedal up to the actuation point (full load stop of the high pressure fuel pump), but no further than this point.
Rice. 14.3 Monitoring the load sensor settings.
Maintain the position of the accelerator pedal (the load cell lever markings must match the full load (high) markings on the housing).
Release the accelerator pedal until it reaches idle speed (the markings on the load cell lever must coincide with the idle speed (low) markings on the housing).
ATTENTION!
Do not use the stops on the load cell housing for adjustment.
Do not loosen the screws on the load cell housing or the nut on the shaft.
Check the ball heads for wear (too much clearance) and for presence of grease.
A.2 Gearbox control Features of gearbox control
The car is equipped with a controller. Depending on the configuration, a push-button switch or joystick can be installed
Rice. 14.4 Controller (joystick) positions: R - reverse; N - neutral; D - automatic range of change of gear ratio for forward movement (Drive);1, 2, 3 - limited ranges of gear ratio changes for forward movement.
Engine startingonly allowed when the vehicle is at rest (brake applied) and the controller is in the neutral position ("N"). If the controller is not in neutral, the engine cannot be started.
CAREFULLY! Do not turn the ignition off/on while driving.
When shifting gearsthe following rules must be adhered to:
The controller must be in neutral position.
The accelerator pedal should be in the idle position and n engine.< 900 min -1.
It is necessary to select the desired range of gear ratio changes.
CAREFULLY! You cannot operate the controller and press the accelerator pedal at the same time.
If you operate a gearbox with the additional “gear release” function, when shifting gears, you must adhere to the following rules:
The controller is in neutral position.
The accelerator pedal is in the idle position and n engine.< 900 мин -1 .
Select the desired gear ratio range and apply the brake. The system only engages the appropriate gear when the brake is applied.
To start moving you needAfter selecting the appropriate gear ratio range, wait approximately 1 to 2 seconds, turn off the brake and press the accelerator pedal.
DANGER! On steep slopes, immediately press the accelerator pedal after releasing the brake. There is a danger of an accident due to the vehicle rolling backwards.
CAREFULLY! At temperatures below -15 °C, do not move. Allow the engine to warm up at idle speed for approximately 5 minutes. Place the controller in neutral position.
Each gear ratio range corresponds to a specific gear range. Gear changes will only occur at specific shift points determined by the electronic automatic gear shift device. There is no point in manually interfering with the process of automatic gear shifting (sequential inclusion of gear ratio ranges).
DANGER! If the transmission is switched to the "N" position while driving, the power flow between the engine and transmission is interrupted. This means loss of engine and retarder braking effect. HIGH RISK OF ACCIDENT! You must immediately apply the brake. For safety reasons, in the event of a malfunction in the electronic automatic gearshift device or in the event of a power failure, the gearbox is automatically switched to the “neutral” position.
When driving on steep slopes, select the required gear ratio range 1, 2 or 3 on the controller. This limits the inclusion of higher gears.
DANGER! In an extreme situation, to protect the engine, the mechanism that blocks the inclusion of higher gears is canceled. In this case, regardless of the selected gear ratio range, the transmission can shift to the highest gear. HIGH RISK OF ACCIDENT! Watch the speed indicator!
When changing the direction of movement of the vehicleBefore switching from forward to reverse or vice versa, the following conditions must be met:
The vehicle must be at rest.
The accelerator pedal must be in the idle position and n engine.< 900 min -1.
The controller should be in neutral position, press the brake pedal if necessary.
Set the controller to D, 1,2,3 or R.
Kick-down mode
Rice. 14.5 Kick-down mode.
To utilize maximum engine power, higher switching points (for acceleration or on slopes) can be called up via the kick-down switch (fig. xxx) or CAN. To do this, you need to press the accelerator pedal beyond the full load response point (kick-down position).
Retarder mode
The retarder brake is a hydrodynamic brake that operates depending on the gear and is wear-free. It is advisable to use the retarder every time you brake. In this way, the working brake system is preserved. The retarder can be activated using hand and/or foot elements.
Conditions for retarder mode (Retarder activated/pressed):
Accelerator pedal in idle position.
The gear must be engaged to drive forward.
Driving speed more than approximately 3 km/h
In this case, the system prevents upshifting (upshift lock).
Rice. 14.6 Retarder brake mode.
CAREFULLY! If the accelerator pedal is depressed, the retarder is released. The action of the mechanism blocking the inclusion of higher gears stops.
The retarder must be turned off in case of icy conditions and when the oil temperature is above 150 °C. In the retarder operating mode, a maximum oil temperature of 150 °C is allowed (maximum 5 minutes).
ATTENTION! After each braking, you must disengage the lever.
Stop, parking.
The vehicle can be stopped at any time, regardless of the controller position. The electronic automatic gearshift device then switches to the appropriate gear used for driving away.
For short stops, the brake must be applied; the gear ratio range can remain engaged.
For long stops, it is necessary to put the controller in neutral and apply the brake.
The special "Neutral When Stopping" (NBS) gearbox automatically shifts to "neutral" if the following conditions are met:
The car is at rest;
Parking brake applied;
The accelerator pedal is in the idle position.
As soon as one of the three conditions is not met, it immediately switches automatically to 1st gear.
When parking, you must place the controller in neutral and apply the parking brake.
ATTENTION! When exiting the vehicle, be sure to apply the parking brake. When the engine is not running, there is no direct connection between the engine and the axle. The vehicle may roll away.
Towing
When towing a vehicle with a working transmission, the following conditions must be met:
The controller must be in neutral position.
The maximum duration of towing is 2 hours.
The maximum towing speed is 20 km/h. At ambient temperatures below -15 °C, the towing speed is 5 km/h.
If a gearbox malfunction is suspected, it is necessary to flange the driveshaft between the gearbox and the transfer case or the driveshafts between the transfer case and the drive axles.
As an exception, in a dangerous situation, towing from the immediate danger zone (e.g. intersection, tunnel, etc.) is permitted without separating the drive chain.
Oil temperature limits
The oil temperature in front of the oil cooling heat exchanger in retarder mode, in exceptional cases, a temperature of 150°C is allowed for a short time (maximum 5 minutes within an hour).
Oil temperature in front of the oil cooling heat exchanger in torque converter mode; the temperature limit for continuous operation is 110 °C, and in exceptional cases, a temperature of 130 °C is allowed for a short time (maximum 5 minutes per hour). During normal driving, the permissible temperature range is 90 -100°C.
The oil temperature in the gearbox oil bath should not exceed I follow Values even at high ambient temperatures: _
If the corresponding permissible oil temperature is exceeded, the following measures must be taken:
Driving with partial load in a low gear ratio range
Disconnect the retarder.
If this does not lead to a decrease in oil temperature, then it is necessary to stop the car, put the controller in neutral and turn the engine to a higher speed.
If after a few seconds the temperature does not drop within the acceptable range, then possible reasons are:
Oil level too low or high;
Faulty coolant circulation;
Gearbox malfunction.
The transmission temperature is checked by the diagnostic system of the electronic automatic gearshift device every time the on-board power supply is turned on, as well as during operation. Overheating of the oil in the gearbox is indicated by the ignition of a warning lamp on the block of warning lamps for electronic systems of the KamAZ 6560 vehicle.
To protect the gearbox in case of failurethe following actions are provided:
Switching to the neutral position (in case of severe problems in the transmission voltage supply, for example, a short circuit);
Emergency vehicle operation mode.
For emergency operation of the vehicle, special times and pressures are stored in the electronic automatic gearshift device to control the pressure. Besides:
The retarder does not work;
The "neutral at rest" (NBS) function does not work;
The engine brake does not activate;
The torque converter lock-up clutch (WK) is open;
Limits engine torque to protect the gearbox (no engine control).
Transfer case
Engage high gear/neutral/low gear.
Gear shifting is carried out only with the vehicle stationary and the input shaft stationary. During shifting, it is necessary to interrupt the transmission of torque from the engine by engaging the clutch.
ATTENTION: switching mechanism - with cam clutches; To avoid damage, gear shifting must be carried out according to the rules.
Rice. 14.7. Pneumatic shifting: high and low gear 2 or 3 positions withlatch, without spring.S- Conclusion - top gear;G- Conclusion - downshift;N- Conclusion - neutral.
Enabling MOD lock
Rice. 14.8. Enabling MOD lock.
This transfer caseprovides permanent drive to the front axle through a center differential, that is, it is impossible to turn off the drive to the front axle. If one or more wheels are slipping, it is recommended to turn on the differential lock. The locking is carried out using a built-in working cylinder with a control pressure of compressed air of 6.5-8 bar.
The differential lock can be engaged while driving,briefly engaging the clutch.
Avoid driving with the differential lock engaged on hard roads with good traction. Exception: steep ascents and descents.
To disable the MOD lock while driving, you do not have to engage the clutch.
After passing a section that requires differential locking, the locking should be turned off.
NOTE: Delayed turning off of the warning lamp after turning off the front-wheel drive or blocking the MOD is not an error in the transfer case system. This is caused by a delay in the transmission in a certain position, which is eliminated when the dog clutch is disengaged after several load changes or steering wheel turns.
Turning on the PTO
The KOM N200 is switched on using a built-in working cylinder at a compressed air pressure of 6.5-8 bar. Before engaging the PTO, press the clutch pedal and wait 5 seconds until the input shaft stops. To operate the PTO when the vehicle is stationary, you need to set the transfer case to the neutral position. The indicator switch confirms that the box is turned off.
IMPORTANT: When turning on the PTO, the input shaft of the transfer case must be stationary!
The clutch pedal should be released smoothly to avoid damage to the dog clutch in the event of incomplete engagement of the PTO (tooth-tooth engagement position)
Before turning off, stop the transmission of torque from the engine by disengaging the clutch.
When stopping the car, the PTO must be turned off!
Due to the slow drop in pressure in the pneumatic system, the PTO is turned off by a pressure spring.
When the engine starts, the pressure rises again and the dog clutch automatically engages.
If the transfer case input shaft is in motion, this can lead to damage to the gear connections.
Towing a car
It is allowed to tow the vehicle in any gear of the transfer case (high, neutral and low).
The driving speed should be selected so that the permissible rotation speed for the transfer case is not exceeded.
RULE: vehicle towing speedhigher or lowergear should not exceed 85% of the maximum permissible speed of the vehicle in the corresponding gear in normal mode.
Since in this case the driveshaft that connects the transfer case to the gearbox is driven, the transmission manufacturer's instructions for towing the vehicle must also be observed.
Vehicle towing speed neutral gear should not exceed 85% of the maximum permissible vehicle speed in top gear.
Towing a vehicle with the front wheels raised is only allowed when the driveshaft connecting the transfer case to the rear axle is disconnected.
If the compressed air supply system malfunctions, the neutral position in transfer cases equipped with a pressure spring switching mechanism can be activated by screwing in a screw.
Rice. 14.9.
Instructions: loosen the locknut and screw it inadjusting screw 1 until it stops.
ATTENTION: After each movement of the adjusting screws, it is necessary to adjust the switching mechanism, which must be carried out by qualified specialists
Preservation and storage
Optimal storage conditionsare achieved by storing the product indoors, in a workshop or garage with moderate ventilation, relative humidity not exceeding 60% and at a temperature of 15° to 20° C.
Before running in, transfer cases are filled with oil. The remaining oil in the box can serve as temporary protection against corrosion.
If the planned storage period exceeds 4 months, it is necessary to preserve the product as described below.
1. remove the breather and close the breather hole in the gearbox housing with a plug;
2. fill the box with oil;
3. rotate the box relative to its center so that the internal cavity is completely filled with oil;
4. While turning the input shaft, engage the high/low gear, front axle drive or MOD lock twice, and also engage the PTO;
5. Store in an upright position.
When stored in optimal conditions(storage indoors at a relative humidity of 60%) work according to paragraphs. 3-5 should be repeated every 6 months.
In more difficult conditions,in arctic or tropical climates, with high salt content in the air (close to the sea), work on pp. 3-5 should be repeated every 4 months.
ATTENTION: do not forget that before turning on the transfer case you must install the breather in place!
The most popular automatic transmission is a conventional automatic transmission, abbreviated as automatic transmission. These are quite reliable units (especially the variants). But they have several weak points, and if you do not follow the operating rules, then you can very quickly “ruin” this transmission, and the cost of a new one or repairing this one is simply HUGE money! One of the destructive reasons is overheating. This is exactly what I want to talk about today in more detail. As usual there will be a text version + video. So let's read and watch...
Overheating can very quickly damage your automatic transmission, and overheating may not even be noticeable and at low speeds in the city (for example, driving in gentle modes), you won’t even notice it, and when the automatic transmission starts to kick, it will be too late. Today we will talk about the causes and symptoms, and the consequences too.
Normal automatic transmission temperature
The machine heats up from the transmission oil (it’s special, called -). This fluid is a transmission link - in simple words, it transmits from the engine to the wheels. All this happens in a torque converter, when one turbine (turbine wheel), conventionally tied to the engine, transfers the oil pressure to another turbine, which is tied to the transmission.
As you understand, it is the oil that heats up, and not the automatic transmission itself, and this heat heats up everything else.
In order to level out excess heating of the liquid in the machine, it is passed through a cooling radiator, which is precisely why destructive heating does not occur.
It is worth noting that the normal temperature of the oil inside an automatic transmission is between 65 and 95 degrees Celsius. If the temperature exceeds 100, and even more so 110 degrees, then you already need to think and watch. Otherwise, breakdowns are nearby
Now let's think about what could be the reasons why the machine overheats.
Causes of overheating
The reasons are often trivial and anyone can encounter them:
- Cooling radiator clogged . Usually it is separate, located next to the main engine cooling radiator. Over time, it can become clogged with lint, dirt, insects, etc. IMPORTANT! Clean it every year (at least wash it with not very strong streams of water)
- Haven't changed the oil in a while . Let's say we rode 150 - 200,000 km and never got into an automatic transmission. A VERY large amount of dirt accumulates, and it can also clog the cooling radiator from the inside. ATF fluid will not circulate, so you have overheating
- Towing a car or trailer . A large traction mass can also lead to overheating and greater wear.
- Slipping . Stuck in mud, sand or snow. If you are slipping in one place, the speed is high, the automatic transmission is thoroughly warming up. Many cars even have an overheating protection system, it turns off the machine after critical heating, and you have an indicator on the dashboard
There is another reason, but this is what I call planned aging. The point here is this - on some cars the automatic transmission radiator and the main radiator for the engine are combined. BUT often now motors can be high temperature, which
As long as you don't haul trailers behind you or skid in the mud. Then it is important for you to flush the radiator and change the oil inside on time
Consequences of overheating
Are the consequences most dire for an automatic transmission? Let's go through the points again:
- Oil (or ATF fluid) . Its operating temperature (the best one) is up to approximately 130 degrees Celsius. If the heating goes higher, then it simply loses its properties and may even burn. And from such burning, sediment may form, clogging many working parts - solenoids, valve body, etc. At a minimum, the performance of your box will be impaired
- Friction discs (or clutches). I already wrote about them, they are both hard (usually metal) and soft (can be pressed cardboard and other impregnated types of special paper). So, “soft” clutches can simply collapse from excessively high temperatures.
- Solenoids. In simple terms, these are specialized valves that open the flow of oil to a package of one or another package of friction discs, closing or opening them. So now solenoids can be 50% plastic, and high temperatures can simply destroy them
- Wiring. Often, special control wires can go to the solenoids, but from high temperatures, they can also melt and collapse.
These are the consequences that can result from overheating of the machine, so it needs to be controlled
Symptoms of overheating
At the very beginning, I advise all owners of cars with to buy the so-called one (I wrote about it in detail, follow the link). You can install the TORQUE program on your phone, install ELM327 in the OBD2 connector and read the readings of many parameters, including the temperature of the automatic transmission. Next, find out your extreme heating characteristics (sometimes in repair manuals) and look at the readings through “ELMKU”. If everything is fine, then OK. If it is exceeded, we look for reasons
Symptoms may be:
- Shocks when switching
- Burnt oil smell
- Gear shifts poorly
- Shifting occurs at high speeds
- The overheat indicator constantly lights up, especially after several sudden starts
- In the most severe cases, gears may not engage at all.
As you can see, nothing fun.
