On some pickup trucks or SUVs, users can see knobs with 2H, 4H, 4L modes, which almost never appear on sedans or hatchbacks. This is essentially a part to install the bridge for part-time four-wheel drive vehicles (4WD, 4×4), meaning the driver is allowed to choose 1-wheel drive or 2-wheel drive.
< strong>2H mode – Rear wheel drive
This is a commonly used mode in which when 2H is selected, the power of the engine is sent to the rear axle only. The benefit of using this mode is increased fuel economy because there is less resistance between the wheels and the road surface.
Conditions Good driving for 2H mode is for road and urban use in dry weather.
4H mode – Full-time four-wheel drive
When switching to 4H mode all wheels are controlled through the transfer case with the center differential open. This means all four wheels are controlled independently (similar to four-wheel drive vehicles full-time AWD). In rough and steep road conditions, 4H mode helps control the journey better.
4L mode – Two slow axles
In case the vehicle is bogged down in mud or the vehicle is climbing a steep slope or pulling heavy objects… 4L mode – Two slow axles will be effective. At this time the vehicle can easily overcome complex terrain. To switch from 4H to 4L, the driver may have to stop or run at a very low speed if they want to switch modes.
From the above limitations, some manufacturers have come up with solutions to help drivers simply switch between engagement modes even when running at high speed. At the same time, expand with 4HLc mode – Full-time fast 2-wheel drive with center differential lock. Meanwhile, 4LLc mode is full-time slow 2-wheel drive with center differential lock.
Thus, depending on the type of terrain and usage conditions of each vehicle, the driver can choose the appropriate drive mode to ensure safety as well as fuel economy.
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