Is the hydraulic retarder worth installing?

The hydraulic retarder, also known as the hydraulic deceleration device, can achieve deceleration braking under non-emergency braking that can be predicted in advance such as long downhill, so as to reduce the use of brakes and avoid problems such as brake failure caused by long-term braking.

According to the previous regulation JT/T1178.2 issued by the Ministry of Transportation, from September 1, 2020, newly produced tractors must be equipped with hydraulic retarders or other auxiliary braking devices trailer axle.

But in reality, many owners are not willing to install liquid slow, in addition to the price is expensive, can not see the long-term return, part of the problem is not clear about liquid slow. Today, we will start from the basic knowledge of liquid retarder, operation matters, maintenance and maintenance of three areas to answer the owners of the relevant questions about the hydraulic retarder.

1, What is the hydraulic retarder?

The hydraulic retarder is a decelerating device, which can slow down the vehicle speed through the hydraulic device, and belongs to the vehicle auxiliary brake device with the engine brake and exhaust brake.

2, the working principle of the hydraulic retarder

The structure of the hydraulic retarder is composed of several large components such as rotor, stator, working cavity, oil storage tank, heat exchanger and so on.

When retarding is needed, the retarder control system will pump the retarder in the oil storage tank into the working cavity between the stator and the rotor. The rotor rotates with the drive shaft, the stator is fixed on the retarder housing, and the rotor is driven by the drive shaft to rotate the retarder oil together. The retarder oil has a certain viscosity, so that the rotor is subjected to the stator's stagnant resistance, at this time the rotor speed will slow down, the drive shaft speed will also slow down, the speed will slow down, and the speed will slow down.

3. Classification of hydraulic retarder trailer axle

According to the different medium, the liquid delay can be divided into oil medium liquid delay and water medium liquid delay. However, at present, there are still technical difficulties to overcome, so the liquid delay on the market is still dominated by oil medium. In terms of price, the price of liquid delay with oil as the medium is about 15,000 to 30,000 yuan, and the price of liquid delay with water as the medium is about 30,000 to 50,000 yuan.

According to the different installation methods, the liquid slow can be divided into series liquid slow, parallel liquid slow, independent liquid slow. Among them, the serial-type liquid retarder is suitable for vehicles with sufficient chassis space, such as tractors or heavy trucks, and it is worth noting that the serial-type liquid retarder cannot be installed after the force extractor; The parallel liquid slow is suitable for light trucks, medium trucks or special vehicles with relatively compact space, and the gearbox may need to be modified if it is installed later. Freestanding fluid retarder is suitable for installation in the middle of the girder and can be applied to any vehicle.

4. Higher fuel consumption after the installation liquid is slow? No. Compared with the traditional water sprinkling device, the slow weight of the liquid can be reduced by about 1t-1.5t, the weight is lighter, the volume is smaller, and the fuel consumption is more conducive to saving.

In addition, the service life of brake pads and tires of vehicles installed with hydraulic retarder has also been extended to a certain extent, which can reduce the number of replacements and save the cost of comprehensive vehicles.

5. Do you need other auxiliary braking methods after installing the hydraulic retarder?

According to the data and practical experience, the hydraulic retarder is enough to undertake 80% of the braking task in the vehicle, and can not use other auxiliary braking methods under the required conditions. However, if the vehicle is operating under special conditions and the liquid retardation cannot fully meet the braking needs, it can also be used with other auxiliary braking devices.

6, can the hydraulic retarder replace the brake?

No, we can't! The role of the hydraulic retarder is to achieve deceleration braking through the braking torque in the non-emergency braking situation that can be predicted in advance, such as toll stations, traffic lights, traffic jams, mountain roads, etc., but deceleration is not equal to stopping, and you still need to rely on the brake pedal when necessary. In addition, when the speed is slow, due to the small braking torque, the hydraulic retarder may stop working, so the hydraulic retarder cannot completely replace the brake.

7. How to distinguish the gear of liquid slow?

Liquid slow can probably be divided into two types of constant speed and slow speed (different brands lead to different gear Settings, generally 1 gear constant speed 2-4/5 gear deceleration).

Constant speed gear is similar to the "constant cruise" mode, that is, the vehicle speed is constant above the set value. Once the vehicle speed is less than the set speed, the liquid delay will automatically exit the working state, if the vehicle speed exceeds the set speed, the liquid delay will continue to enter the working state, real-time control of the vehicle speed.

Slow gear, according to the road conditions and speed, shift the handle from gear to gear, select the appropriate gear to slow down the vehicle, the lowest gear corresponds to the lowest braking torque (generally 25%), the highest gear corresponds to 100% braking torque.

8. How to operate the constant speed gear?

When you want to use a constant speed, put the gearbox into a relatively low gear (ensure that the engine speed is above 1500 RPM), and put the retarder into a constant speed (usually first gear) at the speed you think is appropriate.

9, why to keep above 1500 RPM?

Generally, liquid slow manufacturers recommend the use of liquid slow, the engine speed is maintained at more than 1500 RPM, the purpose is to make the engine cooling system can effectively transfer the heat from the liquid slow "dispose", if the engine speed is below 1500 RPM, the brake work of the liquid slow is likely to become smaller or exit trailer axle.

10, why can't the liquid slow pull to the highest level?

The brake torque provided by the retarder is very high, if you pull to the highest level, the liquid retarder suddenly reaches the maximum braking torque, not only the water temperature will rise sharply, the retarder will exit at high temperature within ten seconds, and the braking force will be lost, and the braking force of the front part will suddenly be larger, which is likely to lead to the occurrence of dangerous phenomena such as pushing the head.

The retarder has been provided with different gears according to the gradual relationship of braking torque, and the owner can gradually pull down the retarder to provide a stable and reasonable braking torque.

In special scenarios, if the vehicle needs to slow down quickly, the retarder handle can be set to the highest level, but other braking means need to be taken to prevent danger.

11, why rain, snow, ice, turning road conditions can not use liquid slow?

Generally speaking, the hydraulic retarded braking torque acts on the drive wheel through the drive shaft, which causes the limitation of braking force. In extreme weather such as rain, snow and ice, the road friction coefficient is reduced. In order to be in case, the hydraulic retarder should be used with caution.

12, after using the hydraulic retarder can immediately turn off and stop?

A: Yes, the hydraulic retarder relies on the engine coolant as the main heat dissipation medium, and can be directly turned off and stopped after use.

13. Can the gearbox be hung into neutral when using slow fluid?

No, although the gearbox is in neutral state, the work of the retarder is not affected, but because the vehicle is in neutral state, the speed is low, the engine water cycle is slow, and the engine water temperature may rise when the liquid is slow for dozens of seconds, resulting in the liquid slow exit, so the gearbox cannot be in neutral when the liquid slow is used.

14, liquid slow is installed on the tractor or semi-trailer?

Since the liquid retarder needs to use the vehicle's own cooling system and transmission system, the hydraulic retarder is mostly installed near the transmission, and there are also cases of installing liquid retarder on the trailer in China. The main way is to change the first axle of the trailer from the support bridge without the power device to the drive axle with the main reducer, and the installed liquid retarder is an independent liquid retarder. Such cases are rare, and market observation is needed to test the actual effect.

15. Does the hydraulic retarder need additional batteries?

No need, the hydraulic retarder as long as the controller and control valve need very weak control current, no additional requirements on the power supply.

16, where is the noise from the slow use of liquid?

There is the sound of liquid impact during the use of the hydraulic retarder, and the exhaust is also reduced through the muffler.

17. Is fluid retardation the same as engine braking?

Different, the engine braking mainly exists exhaust braking, deflating braking and compression release braking three kinds, liquid retarder braking is retarder braking, braking torque is greater than engine braking.

18, how to choose slow oil?

The hydraulic retarder is an efficient energy conversion device, which requires higher shear resistance, flash point and viscosity of the oil, and it is best to select the special oil according to the user manual.

19. Does liquid retardation require special maintenance?

The hydraulic retarder can be basically regarded as a non-wear auxiliary brake component, and its maintenance and maintenance is very simple, and the owner only needs to replace the oil and filter element according to the vehicle type and work load.

20, after the installation liquid is slow, is it once and for all?

No, any vehicle parts have the specified bearing scope, the owner also needs to comply with the use, if there is overload or road conditions are too bad, simply relying on the hydraulic retarder is afraid there is also unreliable situation, but also need to use carefully with other braking devices.