With the continuous development of the domestic transportation industry, the requirements for vehicle production technology are becoming more and more strict, a variety of vehicle "artifact" gradually appeared in people's eyes, hydraulic retarder is one of them.
Hydraulic retarder, also known as hydraulic deceleration device, can achieve deceleration braking in long downhill and other non-emergency braking can be predicted in advance, in order to reduce the use of brakes, avoid braking failure caused by a long time.
According to regulation JT/T1178.2 previously issued by the Ministry of Transport, from September 1, 2020, new tractors must be fitted with hydraulic retarders or other auxiliary braking devices.
But in reality, many owners are not willing to install liquid retardation. In addition to the high price and no long-term return, part of the reason is that the related problems of liquid retardation are not clear. Today, Semi Trailer Manufacturers will start from the basic knowledge, operation matters and maintenance of hydraulic retarders to answer owners' questions about hydraulic retarders.
1. What is the hydraulic retarder?
Hydraulic retarder is a kind of deceleration device, which can slow down the speed of the vehicle through the hydraulic device, and the engine brake, exhaust brake belong to the vehicle auxiliary brake device.
2. Working principle of hydraulic retarder
The structure of hydraulic retarder is composed of several large components, such as rotor, stator, working chamber, oil storage tank and heat exchanger.
When slowing is needed, the retarder control system will pump the retarder oil pump 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 drive the retarder oil to rotate together. Retarder oil has a certain viscosity, so that the rotor is subjected to the stator stagnation resistance, at this time the rotor speed will slow down, the speed of the transmission shaft will also slow down, speed deceleration, to achieve a slow effect.
3, hydraulic retarder classification
According to different media, liquid retardation can be divided into oil medium liquid retardation and water medium liquid retardation. However, at present, there are still technical difficulties to be overcome, so the liquid retardation in the market is mainly based on oil medium. In terms of price, the liquid retardation price with oil as the medium is about 15,000 to 30,000 yuan, and the liquid retardation price with water as the medium is about 30,000 to 50,000 yuan.
According to the different installation methods, the liquid retardation can be divided into serial type, parallel type, independent type liquid retardation. Among them, the tandem type liquid retarder is suitable for vehicles with sufficient chassis space, such as tractors or heavy trucks. It is worth noting that the tandem type liquid retarder cannot be installed with a rear force retractor. Parallel type liquid retardation is suitable for light truck, medium truck or special vehicle with compact space. If it is installed in the later stage, the gearbox may need to be modified. The freestanding liquid retarder fits in the middle of the girders and can be used for any vehicle.
4. Higher fuel consumption after slow installation? Don't. Compared with the traditional water leaching device, the dead weight of the liquid retarded can be reduced by about 1t-1.5t, the weight is lighter, the volume is smaller, and it is more conducive to saving fuel consumption.
In addition, the service life of brake pads and tires installed with hydraulic retarders is also extended to a certain extent, which can reduce the number of replacement and save comprehensive vehicle costs.
5. Do you need other auxiliary braking methods after installing the hydraulic retarder?
According to the data and actual car experience, the hydraulic retarder is enough to undertake 80% of the braking task in the vehicle running, and can not use other auxiliary braking mode if it meets the requirements. However, if the vehicle runs under special conditions, the liquid retardation can not fully meet the braking demand, it can also be used with other auxiliary braking devices.
6. Can the hydraulic retarder replace the brake?
Can't! The role of hydraulic retarder is to achieve deceleration braking by braking torque in non-emergency braking situations that can be predicted in advance, such as toll stations, traffic lights, traffic jams, mountain roads, etc., but deceleration is not equal to parking, and it is necessary to rely on the brake pedal when necessary. In addition, when the vehicle speed is slow, because the brake torque is small, the hydraulic retarder may stop working, therefore, the hydraulic retarder can not completely replace the brake use.
7. How to distinguish the gear of liquid retardation?
Liquid retardation can probably be divided into two types: constant speed gear and slow gear (different brands lead to different gear Settings, generally 1 gear constant speed gear 2-4/5 gear deceleration gear).
Constant SPEED, which is similar to "cruise" mode, keeps the vehicle speed above a set value. Once the vehicle speed is less than the set speed, the liquid retarder will automatically exit the working state. If the vehicle speed exceeds the set speed, the liquid retarder will continue to enter the working state to control the vehicle speed in real time.
Slow gear, according to the road conditions and speed, shift the handle one by one, 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?
If you want to use a constant speed gear, hang the gearbox to a relatively low gear (ensure that the engine speed is above 1500 RPM), and hang the retarder to a constant speed gear (generally one gear) at the speed you think is appropriate.
9. Why should it be kept above 1500 RPM?
General liquid retarded manufacturers recommend the use of liquid retarded, the engine speed is kept above 1500 RPM, the purpose is to make the engine cooling system can be timely and effective to transfer the heat from the liquid retarded "handle", if the engine speed is below 1500 RPM, the brake work of the liquid retarded is likely to become smaller or exit.
10, why can't the liquid slow pull to the highest grade?
Slow device provided by the braking torque is very high, if to the most exclusive, liquid slow suddenly reached the maximum braking moment, not only the water temperature will rise sharply, slow device can be in more than ten seconds high temperature exit, loss of braking force, at the same time part of car braking force suddenly slants big, is likely to lead to have a haircut and other dangerous phenomenon.
The retarder has been provided in different gears according to the increasing relationship of braking torque, and the owner can gradually pull down the retarder to provide a smooth and reasonable braking torque.
In special situations, if the vehicle needs to slow down quickly, the retarder handle can be turned to the highest level, but other braking methods should be used to prevent danger.
11. Why can't we use slow water in rain, snow, ice and turning road conditions?
In general, the brake torque of fluid retardation acts on the driving wheels through the drive shaft, which causes the limitation of braking force supply. In extreme weather such as rain, snow, ice and so on, the friction coefficient of the road is reduced. In case of emergency, the hydraulic retarder should be used with caution.
12, after using the hydraulic retarder can immediately shut down and stop?
Answer: Yes, the hydraulic retarder is to rely on the engine coolant as the main heat dissipation medium, after use can be directly shut down.
13. Can the gearbox be hung into neutral when using liquid retarding?
No, although the work of the retarder is not affected when the transmission is in neutral state, the speed of the vehicle is low when the vehicle is in neutral state, and the engine water cycle is slow. The engine water temperature may rise when the liquid is used for dozens of seconds, leading to the withdrawal of the liquid retarder, so the transmission cannot be in neutral when the liquid retarder is used.
14. Is the liquid retardation mounted on the tractor-trailer or semi-trailer?
Due to the use of its own heat dissipation system and transmission system, mostly in the transmission hydraulic retarder, near the home is installed on the trailer liquid delay case, is the main way to the first axle trailer to take by the bridge without the support of the power unit of the main reducer drive axle, installation of slow for independent type of liquid. Such cases are rare, and market observation is needed to test the actual effect.
15. Does the hydraulic retarder need additional battery?
No, hydraulic retarder as long as the controller and control valve need very weak control current, no additional requirements for power supply.
16. Where does the noise come from in the slow use of liquid?
The use of hydraulic retarder in the process of liquid impact issued by the sound, exhaust is also through the muffler noise reduction.
17. Is fluid retardation the same as engine braking?
Not the same, the engine brake mainly exists exhaust brake, exhaust brake and compression release brake three kinds, liquid retarder brake, brake torque is greater than the engine brake.
18. How to choose the slow oil?
Hydraulic retarder IS an efficient energy conversion device. It requires higher shear resistance, flash point and viscosity of oil. It is best to select special oil according to the user manual.
19. Does the liquid retardation need special maintenance?
The hydraulic retarder can basically be regarded as a non-wear auxiliary brake part. Its maintenance and maintenance are very simple. The owner only needs to replace the oil and filter element according to the requirements of the vehicle type and workload.
20, after the installation of slow liquid is once and for all?
No, any vehicle parts exist the prescribed bearing scope, the owner also needs to comply with the use, if there is overload or road conditions are too bad, simply rely on the hydraulic retarder is afraid there is not reliable situation, but also need to be used carefully with other braking devices.