Tanker - Refueling vehicle - Braking distance is the braking distance, which is an important parameter to evaluate the safety performance of a car. In general, the shorter the braking distance, the safer the car. People often talk about braking distance when discussing the safety of a car, but the meaning behind these figures is easily overlooked. What are the factors that affect the braking distance of the vehicle and how to use the braking distance to ensure driving safety in daily driving? This article discusses with you.
First, the factors affecting the braking distance The current method of evaluating the vehicle's braking distance, which is commonly used in the automotive industry, is the braking distance from the emergency braking to the static state at a vehicle speed of 100 kilometers per hour. So apart from the well-known speed, what are the factors that affect the braking distance?
In fact, the braking distance is also constrained by many complex factors. The main one is braking force and vehicle weight. Braking force refers to the friction between the brake pad and the brake disc and the friction between the tire and the ground. The friction between the brake pad and the brake disc is the brake strength in the general sense, which is mainly determined by the material of the brake pad and the brake disc. At present, cars in the auto market generally use brake disc brakes. The reason is that the disc brake system can dissipate the heat generated by friction during the braking process. If the frictional heat is not effectively distributed, the brake strength will be weakened and even the brakes will fail. Therefore, the use of relatively heat-resistant and wear-resistant brake pads and brake discs will correspondingly increase the braking performance of the vehicle.
The friction between the tire and the ground is static friction when it is not locked, and sliding friction when it is locked. Although the sliding friction force is related to the weight of the vehicle and the material of the tire, in general, the static friction force is greater than the sliding friction force. This involves a topic that the automotive industry is currently concerned about: "Brake locked." Since the static friction force during braking is greater than the sliding friction force, the optimal braking effect can be achieved if the tire is not locked during braking.
As a result, the brake anti-lock brake system "ABS" came into being. The role of ABS is to release the brake when the vehicle is about to lock up, so that the braking force is basically static friction. If adjusted properly, ABS can keep the braking force higher than sliding friction, which means that in this ideal situation, the braking distance can be shorter than that of a model without ABS. Therefore, the brake assist system of the vehicle, especially the configuration of the ABS system, is also a key factor affecting the braking distance.
In addition, many people believe that the longer the vehicle is, the longer the braking distance will be. In fact, this view is one-sided. Because in the case of road conditions, the sliding friction of the vehicle braking is proportional to the weight of the vehicle. That is, the heavier the vehicle, the greater the sliding friction. Although ABS models use static friction when braking, the increase in sliding friction also increases the critical frictional force of static friction. In this way, it is possible to obtain greater static friction braking force for the vehicle. So, it's not that the lighter the car brakes the better.
Second, the rational use of safe braking distance Although the braking distance is related to many complex factors, but for the majority of owners of friends, the regular maintenance of the car, to ensure good car condition is to ensure the daily driving safe braking premise. For example, brake pads should be replaced regularly, and worn brake pads can greatly reduce the braking effect. If the tire is worn badly, replace it in time. Although the vehicle is equipped with an auxiliary brake system such as ABS, if the brake pads and tires are in poor condition, the braking performance of the vehicle will also be reduced.
It should be noted that even if you maintain a good condition, you must maintain enough braking distance when braking, the front brake light is on, your right foot must be placed on the brake pedal. Many owners like to keep a close distance with the vehicle in front and reluctantly brake in the event of a deceleration in front of the vehicle. In fact, this habit is unsafe. If you are driving normally with a distance of 20 meters from the vehicle in front, and the brake light on the front of the car is on, you must prepare the brakes immediately. During the braking process, you must always maintain a distance of 20 meters from the vehicle in front. Make sure that the vehicle is stopped before gradually reducing the distance. Do not think that the distance is far from taking measures, because sometimes when you feel dangerous, the brakes are too late.
Many rear-end accidents are caused by the owner’s excessive confidence in the braking distance of his own vehicle. After all, the braking distance is not just a vehicle factor, but also the driver's response and other human factors. So as far as possible to ensure safe car distance, careful driving is the safe way.
Third, the composition of different brake systems Ordinary air brake braking system consists of brake control mechanism, dual-loop brake mechanism, brake, air compressor and other components, including brake control mechanism, including brake pedal, pedal hanging, manual brake valve Etc.; dual-circuit brake mechanism including gas reservoir, brake valve, low pressure alarm, gas pressure regulator, brake pipe, reversing valve, relay valve, safety valve, drain valve. 2. Working principle, due to the air brake The braking principle of the dynamic system is the same as that of the ordinary air brake. Here we will focus on the working principle of the parking brake. First of all, the structure of the energy storage spring air chamber is explained. The energy storage spring air chamber is the housing of the service brake air chamber. The bore is in communication with the parallel brake chamber of the ventilation joint port of the parking brake air chamber. The piston assembly of the service brake air chamber consists of a piston body, a dense soil cover ring, and a guide sleeve. When the parking brake is applied The push rod only pushes the piston, while the driving brake, the piston is not moving. Before starting the car, the lever of the manual valve should be pulled back to release the parking brake position, so that the compressed air from the parking brake storage The cylinder is filled in the parking brake chamber. Compression of the energy storage spring makes the parked piston return to the non-braking position. At the same time, the service brake piston is also returned by the return spring. At this time, the parking brake is released and the vehicle can start, but if the air reservoir is If the air pressure does not reach the minimum safe value, it is impossible to compress the spring and therefore the car cannot start. This is the main advantage of the parking brake with the energy storage spring. When the driver operates the manual brake valve, the core tube is tight in the spring. By operating the cam, at this time, the intake valve closes, the exhaust valve opens, the air outlet passes through the core tube and the exhaust port to the atmosphere, and the energy storage brake air chamber in the composite brake air chamber also passes through the quick release valve to the atmosphere. The car is in the parking brake state. The maximum travel stroke of the parking brake air chamber is generally 10% larger. Therefore, when the service brake push rod has been moved to the maximum stroke, but the brake clearance is too large to achieve complete When braking, the parking brake air chamber can be deflated, and the storage spring pusher can be further promoted by the energy storage spring to achieve braking.
What are the differences between the air-braked brake and the oil brake? Frequently, the customer who first bought the car asked us this question. A lot of customers asked us to provide the multi-function sprinkler or van that they want to buy with an air brake. The air brake has an oil brake. What are the advantages?
Below we talk about the difference between these two braking methods.
1. The oil brake has a simple structure and a small installation space. It only requires the brake master cylinder, the sub-pump, the oil cup, and the connecting pipeline. No other auxiliary equipment is required; the air brake is more complicated, except for the master cylinder, the cylinder, and the brake Outside the pipeline, there are air pump (connected to the engine through the belt), air reservoir, high pressure controller (adjust pressure, the car can reach 8 atmospheres), relay valve and other components, requiring large installation space and complex structure. And to ensure safety, the rear brake cylinders are now air brakes (increased cost, complex structure).
2. The oil brake response speed is slightly slower, the brakes are softer, and the force is small; the air brake responds quickly, the brakes are rough, and the force is large (the pressure is high and can reach 8 atmospheres).
Therefore, for these reasons, most of the oil brakes are small and medium sized goods vehicles. They are small in size, simple in structure, light in their own vehicles, and do not require much effort. In recent years, there has been a trend towards medium-sized vehicles (loads under 10 tons, some 19 The medium-sized passenger cars below are all equipped with oil brakes. Most of the air brakes are used on large trucks, heavy-duty road wreckers and powdered material carriers. The vehicle has a lot of space, requires a large amount of braking force, and has a long use distance. The reaction speed needs to be fast. The increased cost is reflected in the entire vehicle. The proportion is not much.
3. The parking brake has the essential difference, the former is the central disc brake, is the human type, the latter is the storage spring air brake, is the power type, its energy supply device is completely different.
4. The parking brake of common air brake can only be used when the truck is stationary, because the braking torque acts on the drive shaft. If it is used in the small compression garbage truck, it can easily cause the transmission shaft and the rear. The severe over-load of the bridge may also occur due to the fact that the differential case is locked and the rotation of the left and right wheels is reversed, resulting in deviation or even a U-turn when the truck is braking. However, the energy storage spring brake is not the same, on the contrary, because the parking brake stroke of the storage spring is longer than the service brake stroke, in the case that the brake force is insufficient, the storage spring can be used to assist emergency braking. Therefore, the energy storage spring brake can not only be used as a parking brake, but also can be used as an emergency brake. Therefore, the air brake system is superior to conventional air brakes in terms of brake stability and safety.
5. Air brake There is a strong spring in the brake air chamber. The compressed air lifts the spring when driving. The hand brake is to let go of the air and let the spring lock the brake. When the pressure in the vehicle is too low, it will also produce a brake effect and ensure safety.
6. The conventional brake is the handbrake locks the transmission shaft. When the foot brake is applied, the compressed air enters the brake chamber to lock the wheel. When the handbrake or the transmission shaft mechanically fails, the handbrake malfunctions; when any part of the air pump, pipeline, air reservoir, or brake valve fails, the foot brake malfunctions. The air brake can effectively avoid these dangers through the above comparison. We know the difference between the two braking methods.
in conclusion:
The characteristics of the oil brake: Long brake stop distance, slow response, but the structure is simple, easy maintenance, cheap oil brake mainly used in small trucks and motorcycles, but now there is a general trend of gas brake, some small trucks have begun Equipped with air brake. The main reason is that the customer needs brake brakes for truck safety. Characteristics of air brake: Short braking distance, fast response, complex structure, high maintenance cost, high purchase cost, air brake and air brake for medium and large trucks, On heavy-duty vehicles such as passenger cars, semi-trailers and concrete mixers,
Air brakes are quite different from ordinary air brakes, and they have advantages. If you choose to install an ordinary air brake on a large, heavy-duty road wrecker, it will appear to be a bit "powerless." The difference between an air brake and an ordinary air brake is as follows: 1. The parking brake has an essential difference. The air-braked brake is a stored energy spring air brake, which is a power type, while the ordinary air brake is a central disc brake, which is a human type. The energy supply devices of the two are completely different. 2. The parking brake of the ordinary air brake can only be used when the car is stationary, because the braking torque acts on the drive shaft. If it is used during driving of the car, the drive shaft and the rear axle can easily cause serious overrunning. The load may also occur due to the fact that the differential case is locked and the left and right wheels rotate in opposite directions, causing the car to misalign or even turn around during braking. However, the energy storage spring brake is not the same, on the contrary, because the parking brake stroke of the storage spring is longer than the service brake stroke, in the case that the brake force is insufficient, the storage spring can be used to assist emergency braking. Therefore, the energy storage spring brake can not only be used as a parking brake, but also can be used as an emergency brake. Therefore, the air brake system is superior to conventional air brakes in terms of brake stability and safety.
Most of the air brakes are used in the hand brake system of heavy-duty road wreckers or other special vehicles. The handbrake system of this kind of car usually uses the strong spring in the normal braking state. When the vehicle is to be driven, the driver loose handbrake is a deflation action, must reach a certain air pressure to open the spring, which is the handle You can only drive if you lose it.
Xigong Chusheng Automobile's conventional brake is a handbrake that locks the drive shaft. When the foot brake is applied, compressed air enters the brake chamber to lock the wheel. When the handbrake or the transmission shaft mechanically fails, the handbrake malfunctions; when any part of the air pump, pipeline, air reservoir, or brake valve fails, the foot brake malfunctions. The broken brake can effectively avoid these dangers.
