The Dual Suspension System
The Mobility Solution:
In order to bridge the mobility gap provided by an independent suspension and a solid axle suspension, a new suspension linkage design was invented called the Dual Suspension System. The Dual Suspension System selectively provides solid axle suspension and independent suspension for an automobile which has the advantages of the two and a manner of switching between them according to the driver’s will
High Speed Off-road Independent Suspension Mode
High speed off-road vehicles will usually employ an independent suspension or an independent front suspension (IFS) and can sustain high speed off-road travel very successfully due to the fact that the suspension (unsprung weight) is very light in comparison to the vehicle (sprung weight) and each wheel operates independently from the others. The lightness of the unsprung weight of the vehicle allows the suspension to cycle at extremely high frequencies which translates to potentially attainable high off-road vehicle speeds. Unfortunately, these vehicles fail to have enough suspension articulation to have high mobility. This limitation is a result of the fact that an independent suspension only provides one degree (roll) of freedom per wheel and all four wheels are near “oblivious” of one another. The lack of all four wheels being on the ground and at the same time independent of each other makes the behavior of the vehicle unpredictable and prone to rollovers
High Mobility Off-road Solid Axle Suspension Mode
High mobility off-road vehicles will usually employ a solid axle suspension and can have an extremely high level of mobility or suspension articulation. This level of mobility is due to the fact that each wheel has 2 degrees of freedom (roll, pitch), where the roll is about an infinite amount of longitudinal axes and each pair of wheels is “aware” of each other and reacts to inputs from each other. These vehicles can reach an RTI of more than 1000 and are extremely resistant to rollovers caused by articulation limitations (rock crawling, passing a ditch etc.) A vehicle’s roll angle is an imposed average of the front and rear axle angles and is therefore manageable and predictable. On the other hand solid axle suspension vehicles suffer from a very high unsprung weight. A solid axle normally weighs a few hundred pounds which slows down the cycling ability of the suspension to a point where trying to cycle it quickly will almost surely result in over excitation of the entire vehicle where it rolls or pitches-over