Practical skills for reversing semi-trailer

1. When the semi-trailer is moving forward, the angle between the main vehicle and the trailer converges automatically. When the semi-trailer is moving forward, whether it is moving straight or turning, the angle between the main vehicle and the trailer will remain unchanged or gradually decrease. This angle is convergent and will not diverge automatically. That is, when we drive the semi-trailer forward, whether it is moving straight or turning, we don’t have to worry about the angle between the main vehicle and the trailer getting bigger and bigger, making the main vehicle and the trailer twisted into a dough. That is, it is relatively easy to drive forward because the line of sight is good and the vehicle can be controlled by itself.

2. When the semi-trailer is reversing, the angle between the main vehicle and the trailer diverges automatically. When the semi-trailer is reversing, whether it is reversing straight or turning, the angle between the main vehicle and the trailer will not remain unchanged or gradually decrease. This angle will gradually increase and diverge. That is, when we drive a semi-trailer to reverse, we must continuously control the running track of the semi-trailer by turning the steering wheel correctly, so that the angle between the main vehicle and the trailer remains within a controllable range, so that it does not diverge quickly and twist into a twist. That is, reversing is relatively much more difficult, because the line of sight is poor, there are many blind spots, and the vehicle cannot be controlled by itself, and manual control is required.

3. The law of slight divergence suppression of the angle between the main vehicle and the trailer when the semi-trailer is reversed in a straight line. Reversing in a straight line is the most basic and the easiest. When reversing in a straight line, if you find that the rear corner of the car is deviated to the left, you should turn the steering wheel slightly to the left, and the trailer will return to the straight line; if you find that the rear corner of the car is deviated to the right, you should turn the steering wheel slightly to the right, and the trailer will return to the straight line.

4. The law of semi-trailer turning and reversing. When turning and reversing, we should try to make the main vehicle and the trailer form a suitable angle in the direction of the turn (operation method: turn the steering wheel in the opposite direction of the desired reversing direction), and then keep this angle unchanged (operation method: turn the steering wheel twice in the desired reversing direction), so that the turn and reverse can be achieved. The gentler the bend, the smaller the angle between the main vehicle and the trailer should be; the sharper the bend, the larger the angle between the main vehicle and the trailer should be.

5. The law of establishing, destroying and restoring the balance state of the angle between the main vehicle and the trailer when the semi-trailer turns and reverses (the law of turning the steering wheel less and returning more). For example, when turning and reversing to the right rear, a suitable angle has been formed between the main vehicle and the trailer to the right, and this angle is kept unchanged while reversing to achieve a state of balance. If the steering wheel is turned 30 degrees to the left at this time, the balance state of the angle between the main vehicle and the trailer is broken. After a while, the angle between the main vehicle and the trailer will become larger. If the main vehicle and trailer need to keep the newly formed larger angle unchanged, that is, the angle between the main vehicle and the trailer is restored to a balanced state, the steering wheel must be turned right more than 30 degrees. That is, if the steering wheel is turned 30 degrees to the left, the balance is broken, and it is not possible to turn it back to the right 30 degrees. The steering wheel must be turned right more than 30 degrees to restore the angle between the main vehicle and the trailer to a balanced state. This is the law of turning the steering wheel less and more for semi-trailer reversing.

6. The law of retracting and maintaining the angle between the main vehicle and the trailer for semi-trailer reversing. For example, if you need to turn a right angle to the left rear direction, if you turn the steering wheel 40 degrees to the right first, the angle between the main vehicle and the trailer will become larger and larger to the left. This process is called release. When a suitable angle has been formed between the main vehicle and the trailer, if you quickly turn the steering wheel 80 degrees to the left at this time, the angle between the main vehicle and the trailer can remain unchanged and reach a balanced state. This process is called maintenance. At the end of the reverse turn, quickly turn the steering wheel to the left to the bottom, so that the angle between the main vehicle and the trailer is quickly reduced, and the car body returns to the straight position. This process is called retraction. The smaller the angle between the main vehicle and the trailer, the easier it is to retract, and the timing of retraction can be later; the larger the angle between the main vehicle and the trailer, the more difficult it is to retract, and the timing of retraction should be earlier. For complex reversing tasks (such as reverse S-bends), there may be no “holding” process in the middle. So let go first, and then quickly retract; then let go in the opposite direction, and then quickly retract. As for the degree to which you should retract, that is, how to determine the timing of retraction, this depends on experience.

7. When a semi-trailer is reversing, the law of strategic and predictive steering and returning direction. When a semi-trailer is reversing, the angle between the main vehicle and the trailer cannot be enlarged all at once, and the angle between the main vehicle and the trailer cannot be reduced all at once. It requires strategic vision and advance judgment. The longer the trailer is, the longer the process of releasing and retracting will be, and the more you need to do the release and retraction actions in advance.

8. When a semi-trailer is turning and reversing, the law of taking into account both the front and rear of the vehicle. Because the semi-trailer compartment is very long, when turning and reversing, the turning radius formed by the main vehicle and the trailer is often large, and the difference between the inner and outer wheels is also large. In the case of obstacles around the reversing site, if you only care about the front of the vehicle and ignore the rear of the vehicle when reversing, it is easy to cause a scratch accident. Therefore, it is necessary to take into account both the front and rear of the vehicle at the same time.

9. When a semi-trailer is reversing, the law of repeatedly turning the steering wheel must be used. When reversing a semi-trailer, whether it is reversing straight, reversing turning, or more complex reversing tasks such as reverse S-bends and side parking, it is inseparable from repeatedly turning the steering wheel in both directions. Reversing a semi-trailer and repeatedly turning the steering wheel is not a problem, but a necessity. Anyone who reverses a semi-trailer and only turns the steering wheel in one direction cannot complete the reversing task. The difference between an expert and a novice is that an expert can complete the reversing with the least number of steering wheel turns (for example, when reversing to turn right at a right angle, the expert starts to turn the steering wheel to the left once, turns the steering wheel to the right once on the way to keep the turn, and turns the steering wheel to the right to straighten it at the end. In theory, only 3 times are needed; of course, in actual practice, it may be necessary to swing the steering wheel slightly left and right a few times to correct the error). Novices have no rules for steering the wheel, and are more blind, random, and arbitrary. They keep turning the steering wheel repeatedly, which makes them tired and the failure rate is still high.

10. Semi-trailers have inherent advantages over single vehicles. Now most trucks that run long-distance freight are semi-trailers. Have you ever thought about it? Why do semi-trailers have such a big advantage? You may think that the semi-trailer compartment is just long, right? If the compartment of a single vehicle is also that long, it will not lose to the semi-trailer, right? In fact, it is not possible to make the compartment of a single vehicle as long as that of a semi-trailer. The length of the compartment of a single vehicle is the length of the drive shaft. If the drive shaft is too long, it will be overloaded; and no matter how long the trailer is, the drive shaft of the main vehicle is very short and not easy to break. In addition, when the main vehicle and the trailer of the semi-trailer form a 90-degree angle, the trailer can turn in place, that is, the narrow and long trailer can complete a sharp turn in a very small field. But a single vehicle cannot turn in place, that is, a narrow and long single vehicle is very stupid to turn. Although the trailer is long, the main vehicle is very short, and the turning is very flexible, which can then drive the trailer to turn a sharp turn. In addition, the semi-trailer can realize the drop-and-hook transportation, and one head can pull multiple trailers one after another. But a single vehicle cannot realize the drop-and-hook transportation, and when the compartment is loading and unloading, the head cannot drive away to pull the compartment elsewhere.