There are rules for the addition and subtraction of semi-trailers

28 Mar.,2022

The range from the lowest gear to the highest gear is the adaptation range of this gear. Avoid using the lowest or highest gear for a long time as much as possible.


Gear speed and gear are appropriate:

The range from the lowest gear to the highest gear is the adaptation range of this gear. Avoid using the lowest or highest gear for a long time as much as possible.

Shift (up, down):

In principle, as long as the gear range is reached, the gear can be changed, and the choice of gear should consider the semi-trailer speed, power and economy.

Drag file:

A speed lower than the lowest gear is generally called a drag gear. The drag gear will make the semi-trailer run weakly, move back and forth, and in severe cases, it will cause the engine to stall.


When the speed of the semi-trailer reaches a higher speed, the upshift should be implemented. Generally speaking, the timing of the upshift of the high-speed semi-trailer is the engine speed of 3500-4500 rpm.

Back out:

When the semi-trailer speed is close to the minimum semi-trailer speed of the gear, the gear should be reversed. The timing of the high-speed semi-trailer should be controlled within the range of the speed of this gear - medium and low, and it should not be lower than the lowest half of the gear at the latest. The choice of the trailer speed and the timing of the gear shift should be mastered according to the road surface and power demand;

The use of gears under different road conditions:

Speed up and shift up: Before entering the normal driving speed, you should try to increase the reversing speed of the semi-trailer in this gear (the semi-trailer speed corresponding to the high engine speed), so that the semi-trailer has enough power to drive after the upshift. This is especially important when implementing an uphill shift.

Maintain gear dynamics:

When driving uphill and adjusting the speed on the general road, the gear speed should be kept at a medium speed (the engine is running at a medium speed), so that the semi-trailer vehicle has sufficient momentum and speed adjustment performance when driving. Normal driving: when driving normally, the speed is not It needs too much adjustment, and the gear speed selection is on the low side, in order to facilitate the economy of driving.

Downhill gear:

For general non-dangerous downhills, the gears can be properly shifted, the downhill resistance is small, the acceleration performance is good, the upshift operation can be performed in advance, and the upshifting can save fuel. Using the brake semi-trailer for a long time will cause the brake semi-trailer to decrease in efficiency and failure. The corresponding low gear should be hung, and the engine should be used to restrain the semi-trailer speed. The principle of gear allocation should be based on the fact that it is not necessary to use the brake semi-trailer for a long time to decelerate.

Shift operation:

Depress the clutch pedal, release the accelerator quickly, shift the gear to the desired gear, cooperate with the appropriate accelerator (or no accelerator) according to the gear speed, and quickly lift the clutch to the semi-contact state of the contact point. Gently release the clutch pedal.