Honest Auto Tech

Hello This is Bhushan. I will try to give you AutoGyan (Automotive information)/Honest Automobile Reviews.


Sunday, September 23, 2018

What is 2H, 4H and 4L in 4 X 4/4WD vehicles

Hello Everyone,
Welcome to my new blog

In the last blog, explained the difference between 4 X 4/4WD and AWD, if you want to read it here is the link What Is Difference Between 4WD /4 X 4, And AWD? today will clear some more concepts about the 4WD vehicle.

So when do we engage 4WD mode in a vehicle?
Its answer is when we are too stuck in muddy conditions or we are going to off-road drive. Put your vehicle in the 4WD mode before you get stuck.
All of the off-road vehicles are equipped with the two axles I.e front and rear and transfer case to distribute power to two axle, now what is transfer case "It is a part of drivetrain of four wheel drive or all wheel drive vehicles, it equally transmits the power to front and rear axles with the help of drive shafts"

The transfer case is not only the part for distributing the power but it also has some of its extra capacity which is provided in the vehicle with extra small gear level or new vehicles are having knob written with 2H, N, 4H, 4L.

So what do that terms mean?
Selector Switch 

What is 2H?

2H is used for normal road driving conditions where you expect more fuel efficiency from your vehicle. in this mode Two wheels are driven, usually the rear or front it is according to the manufacturer, the H=high-range means the normal gear ratios are used for everyday driving. In an exceptional case, Some vehicles may be constant 4WD or all-wheel drive, in which case they won't have the 2H option but in India, it's not available because of the reason fuel efficiency.

What is N?

N is a neutral position, the center differential is disconnected from the transmission.

What is 4H?

4H is used for normal-speed driving, but for when you need extra traction to rotate all the wheels. These situations might include muddy roads, ice or snow-covered roads, or hard-packed sand. At that engage your lever or make sure you're in the 4H mode it will engage your both front and rear wheels in high-range, using the same gear ratio as of the 2H for normal driving speeds. The front wheels come in traction, making the vehicle more stable on loose surfaces and not to stuck in the obstacle.

What is 4L?

4L is used when you need more torque but less speed, I.e it provides max torque and max power.
It is used in conditions like sharp inclination and declines, deep muds, rocky surfaces, the 4L mode makes the vehicle to crawl in slow speed. Front and rear wheels are driven in low range speeds, all four wheels turn much more slowly per revolution than that of they would in high-range, it results in slower road speed but gives higher torque basically, it multiplies the torque to 3times, it is according to manufacturers the 4L ratio of Mahindra Thar is 3.73 : 1, means it will give the torque output of 600N-m with 4L mode, which assists the vehicle on inclination and declination, the lower gearing ratios gives the vehicle engine braking, making it easier to control on the descent.


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