How does a truck run a long downward slope safe and sound?
In daily life, drivers will face various driving conditions. Whether an upward slope or a downward one, it is of vital importance to make sure safe driving. However, how to safely run a long downward slope?
I.Practice regular checkups
To ensure safe and hassle-free driving, the driver should check up on every part of the truck before leaving off, during the journey, and after reaching the destination.
When it comes to regular check-ups of trucks, a certain number of drivers are not willing to pay much attention to it. Some think it is not essential since no accident happens, others consider that it will cost a certain time and money. Even a small proportion of people complain that 4S shop charges too much on subtle issues. As a result, unexpected incidents come into existence every day because of such omissions. Seriously speaking, road accidents happen simultaneously at every moment across the world, causing injuries and damage to public services and property, and more devastating, stopping hundreds of vibrant hearts from beating. The main reason is that most drivers devalue the importance to practice termly check-ups, focusing on the advisory circulars of safe driving, and solving visible breakdowns of trucks. In order to avoid previously mentioned disasters, drivers must develop a good habit of checking up on trucks periodically.
As we all know, trucks running a downward slope will more possibly cause accidents. Having a good knowledge of check-up tips helps a lot. First, the driver should carefully check the brake system. When one part goes wrong, it must be repaired or replaced. The drivers can open the engine hood on their own to check if there is an abnormal phenomenon. Pull out the oil dipstick and clean it up, and place it in its original position. The truck works well if the oil volume is between the maximum degree and minimum degree of the oil dipstick.
Second, notice the volume of coolant. The coolant exerts an influence on reducing heat generated by the engine in summer and preventing the dynamic system from being frozen in winter. Its other function is corrosion protection, which makes sure that no deposits and corrosion affect pipes in the process of heat dissipation. If it appears in a different color or deposes, it is time to replace it. If no emergency, the driver had better resort to a professional maintenance shop to replace it. Third, brake oil mixed with water will be less easily boiled, leading to insufficient power, seriously affecting braking system and safe driving. Fourth, check boosting oil. If the color turns black from red, it needs replacing in a timely.
II.Decrease speed in advance
Defensive driving is an indispensable lesson. Facing a long downward slope, the driver should prepare for solutions in advance, be cautious at all times and always notice warning signs and the location of anti-risk passage, whether the truck is assembled with auxiliary braking equipment or not. When the truck runs downhill, the driver should change the gear to the lower level, because the towing drag force of the engine exerts an inverse force on the speed when the truck remains at a lower-speed state. Additionally, a low driving speed reduces the braking frequency, and the risk of thermal decay and avoids traffic accidents when the truck suddenly decelerates.
Meanwhile, the driver should not slide into neutral gear. Sliding in neutral gear will not save oil consumption, but will bring about much more potential hazards. Further explaining, when the truck is in at idle speed, the air in the air pump is less. However, running a long downward slope needs frequent braking operations, which consumes more air. If the air is not enough, the risk of braking inefficiency is high.
III.Auxiliary braking
（1）Engine braking
Engine braking means lifting the accelerator pedal without depressing the clutch and using the engine’s compression stroke to generate compression resistance, internal friction and intake and exhaust resistance to create a braking effect on the drive wheels.
The common explanation of “engine braking” is that when the brakes are applied, the accelerator is lifted and the clutch is not depressed, the engine and gearbox are still connected and the gearbox is moving with the engine, relying on the engine’s resistance to reduce the speed of the truck and play a certain role in braking. When the engine braking is needed, hang on to the gears, release the throttle and do not step on the clutch.
When going down long slopes, rugged mountain roads and other steep roads, engine braking must be used, combined with intermittent braking to control the speed of the truck. As a result, prolonged use of the brake will affect the braking effectiveness, or even loss of the braking effect. Therefore, when encountering such a situation, you should stop and take a break, wait for the brake hub and brake shoes to cool down and then continue driving.
Weichai is familiar with WEVB as a standard feature of its engines. As mentioned earlier, this technology is the MAN EVB technology introduced by Weichai, the “W” in front stands for Weichai in pinyin. The braking power of WEVB is 160kw at 2000r/min and 230kw at 2500r/min.
（2）Retarder Braking
In simple terms, a retarder is an auxiliary braking device. It is generally used on large trucks to help with truck braking on a long downward slope, allowing the truck to slow down smoothly without the wear and tear and heat caused by using the brakes. Large trucks require an incredible amount of braking power due to their greater weight. The normal drum and disc brakes we all know tend to lose braking power when going downhill for long distances due to increased temperatures, which can lead to rear-end collisions and rollovers, resulting in major traffic accidents. To combat this phenomenon, electromagnetic and hydraulic forces have been used to develop devices that do not lose additional power and can provide a constant supply of braking power.
Firstly, from a safety point of view, GB 7258 requires heavy trucks to be fitted with auxiliary brakes. Secondly, heavy trucks fitted with a hydraulic retarder can, if used effectively, not only ensure safety for truck users during truck operation, but also reduce costs and increase efficiency.
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