From the GMC Sierra, to the Honda Prelude, all-wheel steering has been offered in many different vehicles of all shapes and sizes for the past few decades. While four-wheel steering is not a new concept in cars, it has seen a resurgence in the last few years.
With all four wheels steering, instead of only the front two, this technology offers unprecedented control and maneuverability. That being said 4 wheel steering takes some getting used to. We caught up with a Master Mechanic to outline the main advantages and disadvantages of a four-wheel steering system.
With four-wheel steering, your vehicle will undoubtedly respond faster when turning and switching lanes. More precise and controllable steering is safer for you, fellow drivers, and pedestrians. While it might not make a world of difference in everyday driving scenarios, it can when an unexpected obstacle is in your way.
When the roads are wet or icy, some corners can be quite challenging. Four-wheel steering will help your car complete corner turns with stability and control. The aim is to decrease the amount of yaw that the car experiences, keeping it planted and less skittish through fast bends.
Decreasing yaw means that the car's weight movement around its vertical axis is minimised, thus the car leans less into and out of a corner. Turning the rear wheels in the same direction as the front wheels therefore simulates the car's wheelbase increasing in length, helping stability and increasing potential cornering speeds.
Don't think that those rear wheels visibly turn however — we're talking degrees maximum either way. Previously only saved for such beasts as the Nissan Skyline or more recently the Porsche , four-wheel steering will make the new Megane R.
And with the company openly aiming to take back the front-wheel drive record at the Nordschleife, the car certainly has the tech to launch a possible assault.
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Hi High speed straight line stability. Relative Wheel Angles and their Control The direction of steering the rear wheels relative to the front wheels depends on the operating conditions. At low-speed wheel movement is pronounced, so that rear wheels are steered in the opposite direction to that of front wheels Fig.
This also simplifies the positioning of the car in situations such as parking in a confined space. Since the rear wheels are made to follow the path on the road taken by the front wheels, the rear of a 4WS car does not turn in the normal way.
Therefore the risk of hitting an obstacle is greatly reduced. As a result, the car moves in a crab-like manner rather than in a curved path. This action is advantageous to the car while changing lanes on a high-speed road. The elimination of the centrifugal effect and, in consequence Fig. Movement of steered wheels Honda. Honda 4WS layout. In a 4WS system, the control of drive angle at front and rear wheels is most essential.
The Honda and Mazda systems vary in the manner their wheel angles are controlled. Honda system uses mechanical rear steering and the Mazda layout incorporates a rear gearbox, which is power-assisted as well as electronically controlled. Both systems have a power-assisted rack-and-pinion steering layout for the front steering gearbox with a take-off connection to control the rear steering gear box through a centre, or transfer, shaft.
Two or more universal joints installed on the shaft allow the small variations in drive angle. This system is dependent on the steer angle so that the movement of the rear wheels is controlled by the angular movement of the front wheels. For steering of the front wheels up to about degrees, the rear wheels are so arranged that they turn through a small angle in the same direction as the front wheels.
Beyond this angle, the rear wheels gradually straighten up and then turn through a comparatively large angle in the opposite direction Fig. An epicyclic gear mechanism incorporated in the rear steering gearbox Fig.
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