4 Wheel Drive in vehicles is a term essentially referring to the position when four wheels are powered by the driveshaft through two axles to take the torque for movement of a vehicle.
Wheels in a vehicle are connected on two ends via an axle. Four wheelers, therefore, have two axles – front axle and rear axle.
The vehicles are designed to operate between “2 Wheel Drive Mode” & “4 Wheel Drive Mode”.
Similarly, a six-wheeler having three axles can also run in 4 Wheel Drive mode, providing torque to only four out of six wheels.
In normal cases, vehicles run on 2 Wheel Drive mode, torque is transferred to only front axle, i.e., front two wheels.
Why 4 Wheel Drive?
4 Wheel Drive is basically helpful in the movement of the vehicle in twists and turns, off-road drives, traction on rough routes or similar cases.
In cases of rough drives, providing torque to only front axle does not serve well. 2 Wheel Drive is not able to derive the strength of the vehicle to keep a grip on the pavement and often can cause the vehicle to skid.
Driving on all four wheels makes the drive smooth in the bumpy passages.
Speed Limit in 4 Wheel Drive
The speed limit in the 4 Wheel Drive Mode, however, depends on several factors. Different models from different manufacturers are designed to be run on different optimum speeds while in 4WD.
The mechanism of engine system defines the optimum speed in many cases.
Normally, the vehicle can go up to a speed of 55 to 65 miles per hour in 4 wheel drive. Higher than that is not recommended though.
Also, the point should be kept in mind that while switching to 4 wheel drive mode, the speed of the vehicle should be as recommended by the manufacturer.
The information is usually provided in the customer's manual.
In 4 Wheel Drive also, there are two ranges on which a vehicle runs – “4-High” & “4-Low”.
Along with the information about the switching speed of a vehicle to turn on 4 WD mode, it is necessary to have the understanding as to which range you should choose to drive depending on driving conditions.
Switching on to the wrong mode in a wrong place may very well hinder your progression on the tracks.
Furthermore, it may prove problematic if you are moving in a narrow lane which can block the traffic, or some steeper terrain, or in any similar situation.
Four-High Mode of 4 Wheel Drive
While driving on rough patches of road, gravel roads, or when pavements are sketchy due to snow storms, etc., it is recommended to switch on Four-High.
You can drive the vehicle on all normal speeds in 4-High mode while gaining a good grip over the track.
The mode works best for highways, propagating the vehicle pretty smoothly and with good speed.
While the 2 Wheel Drive mode runs the risk of skidding in the pavements which are rough due to poor maintenance, 4 Wheel Drive on 4-High will give the vehicle better speed with an effective grip on the traction in perfectly smooth manner.
Four-Low Mode of 4 Wheel Drive
The four-low range of 4WD is recommended for strenuous drives, like in muddy areas, deserts, driving through water streams, snowy paths or climbing up and down on those rocky hill stations or mountains.
Basically, the mode is switched on to make a proper grip on difficult to move tracks with a low speed.
Pitching the speed higher will do nothing but consume extra power from the engine while increasing the torque in the wheels with no better grip on the path, and vehicle anyhow will be unable to pick up the pace due to the exertive texture of the track.
Driving a vehicle on rough tractions and steep terrains is not an easy task. Along with technically sound and equipped engine systems, it is the ability and skill of the driver to a great extent which pulls off the feat.
4 Wheel Drive system is developed to help drivers keep the vehicle moving in all driving conditions.
Having the knowledge about which mode to switch on and at what speed determines it all, the system is now becoming more popular in heavy-duty vehicles.
Also, because of its off-road capacity and higher efficiency; when the light-duty vehicles continue to use it for better performance of the vehicle in terms of speed.