Suspension for off road vehicles

One of the big innovations in automotive suspensions in the last fifty years was the introduction of the anti-sway bar, or sway bar in common parlance. This device is designed to keep a vehicle more nearly level when it goes around a corner. Most automobiles have one in the front suspension, some sportier cars also have one in the rear.

When driving a four wheeled vehicle, such as a Jeep, off the highway, i.e. on surfaces that are not paved, you want to keep all four wheels in contact with ground as much as possible. An uneven dirt surface does not offer as much traction as a smooth paved surface. The anti-sway bar, and the stiff chassis of most modern vehicles combine to make it difficult to keep all four wheels in contact with the ground when the terrain is uneven.

So we have a conflict here. For highway use, we want a stiff chassis that does not roll much. For off-road use, we want a suspension that will keep all four wheels in contact with the ground.

My idea is to connect the front and rear axles with an anti-sway linkage. Current anti-sway bars work by causing both wheels on one axle to move together. When one wheel goes up, the sway bar exerts pressure on the other wheel to move up. My idea is to couple wheels diagonally. That is, when the left front wheel is forced up, my cross linked sway bar would exert an upward force on the right REAR wheel. Likewise, when the right front wheel drops down, a downward pressure would be exerted on the left rear wheel.

If you visualize a vehicle with solid axles (like a Jeep, or a heavy duty truck), when the front axle tilts one way to accommodate the terrain, the rear axle would tilt the other way. In off road situations, this would help keep all four wheel in contact with the ground. On the highway, it would act like a pair of conventional sway bars. A further benefit would be that tend to keep a more upright position when traversing uneven terrain. The cross linking of the axles means that attitude of the vehicle would not be following one axle more than the other, its' position would be determined by the average of the position of the two axles.

Constructing such a suspension for an existing vehicle would take some talented engineering. Using an all mechanical solution of bars, links and torsion springs would have the advantage of being reliable, but would no doubt be difficult to construct around the existing frame and suspension. A hydraulic system might be easier to install, but would need careful engineering to be reliable. Either system would need extensive testing before it could be sold. It would need to be tested off-road to see whether it did if fact help vehicles negotiate uneven terrain and whether it will hold up to off-road abuse. It would also need on-highway testing to ensure that it did not adversely affect the behavior of the vehicle, especially in emergency situations.