Firstly, from a design perspective, the cab of heavy trucks adopts manual or electric hydraulic lifting, and safety protection has been implemented in the design. After the cab is flipped in place, the center of gravity of the cab is in front of the flipping shaft. Even if the hydraulic cylinder breaks, the cab will only tilt forward and will not cause harm to operators near the engine. During the lifting process, it will be noticed that the hydraulic cylinder is slowly lifting against the cab. When the center of gravity of the cab passes through the flipping axis, the cab will automatically roll forward under the action of gravity. At this time, the force on the hydraulic cylinder is not thrust, but tension. Therefore, as long as the cab is flipped in place, safety accidents can be avoided. Moreover, many repair shops have corresponding safety support rods for secondary protection to prevent such accidents from occurring. But at the user level, there are many security risks.
Mechanical diagram of the cab after flipping in place
Research has found that many drivers do not flip the cab in place, but instead "just enough", such as replacing the air filter, checking the oil dipstick, etc., only flip it 30 degrees, and the center of the cab is still behind the flipping shaft. On the surface, it appears that there is a hydraulic cylinder supporting it, so there will be no problem. However, the rubber seals in the hydraulic cylinder will age after 4 to 6 years of use, leading to minor leakage issues and sudden drop, posing a significant safety hazard.
Why not flip the cab into place? The user's explanation is simple: firstly, there are too many items in the driver's cab, and once flipped in place, it will cause many items to scatter. The cab is the driver's home. There are "pots and pans" in the middle of the floor. There are clothes and quilts all year round on the upper berth. There is a small shelf at one end of the lower berth, where there are many Household goods and food. If the cab is completely turned in place, that is, it rotates 60-70 degrees (the maximum turning angle is different for different models), the objects that are not firmly fixed will inevitably fall to the ground, and even the hard objects stored on the upper bunk will break the windshield if they fall; Secondly, the flipping time is too long. Usually, it takes 1 minute for the cab to be flipped using electric hydraulic pressure, and 3 minutes (approximately 90 to 120 times) if manual hydraulic pressure is used for flipping. Many drivers say, "I just take a look at the oil dipstick, which lasts for a total of 20 seconds. It takes several minutes to flip it over at a time, which is really unnecessary. This is supported by hydraulic cylinders, and there is no problem." Obviously, many drivers lack safety awareness and are not aware of the safety hazards of illegal operations.
So, in addition to requiring and reminding users to strictly comply with safety operation regulations, can truck companies add error prevention and redundant design to their existing foundation, and prevent such accidents from happening from the design source? After extensive research, Shangchebang has put forward the following suggestions.
Firstly, reduce the number of times the cab flips over. According to the research and statistics of Shangchebang, the daily inspection of the oil dipstick by drivers accounts for 30% -40% of the times the driver's cab is overturned. It is recommended to learn from the design ideas of many European heavy-duty trucks and design the oil filler and dipstick at the front of the cab. Drivers only need to open the front panel of the cab to complete the oil dipstick inspection and refilling work.
Secondly, design "one click to place function" and "violation operation alarm". At present, the electric flipping of domestic models requires operators to keep pressing the button, and once released, it will stop. Some operators have a "quick temper" and can experience impatience when pressed for a long time for one minute. Additionally, as the vehicle is not equipped with a flipping position sensor, it is not possible to determine whether the cab has flipped into place. Suggestion: The electric flipping of the cab is designed to be started with one button, which means that the operator only needs to press the button once, and the hydraulic pump can continue to work until the oil cylinder reaches its maximum position before stopping to ensure that the cab is flipped in place. If there is an emergency situation during the flipping process, such as someone suddenly passing in front of the cab, you can press the button again to stop the emergency. Additionally, a flipping position sensor is installed. When the driver's cab is not flipped in place, the vehicle can emit a continuous "beep" alarm sound to alert the operator.