The Evolution of Power Steering

Of all the drive components under scrutiny today, one of the greatest may very well be the steering system. Aside from aesthetics, most never even realize the progression that is taking place. With the exception of introducing hydraulic assisted systems on a commercial scale in 1951 - the most profound change from a driver’s perspective - subsequent design changes appear minimal. From a technological perspective however they couldn’t be more profound.

Today’s design teams are faced with the challenge of riding the leading edge of evolution with "Drive by Wire" systems which actually take the mechanical linkage totally out of play. End users have already seen them appear on a commercial level with heavy equipment and of course military applications. Driven by economic desire for greater fuel economy and reduced maintenance costs, the removal of the heavy linkage could very well get us to that next level. However, that does remove the redundancy of the mechanical linkage, a major safety concern. Some automakers are aggressively projecting production line roll-out as soon as a year from now.

Aside from obvious legislative scrutiny, designers also need to consider driver experience, a major concern when it comes to vehicle dynamics. The steering system is a point where the driver is in direct connection with the component. The last transition made with driver dynamics was the introduction of the ABS system where educating the consumer on how to use it and what to expect upon engagement was a major part of the transition. The same holds true for power steering.

Drivers are used to the resistance of the hydraulic assist along with the auditory input as we near the steering stops when parking or turning at lower speeds. Hybrid systems found in many of today’s models (Electro Hydraulic Power Steering) still give the driver the feedback they’re used to while increasing the effectiveness of the system exponentially. Full electronic assist steering has made its way to the marketplace, removing the hydraulic component while leaving the mechanical linkage intact.

We now have torque and position sensors in the steering column, wheel speed sensors and other inputs that allow us to adjust the assistance applied during various driving conditions. This is a great advancement when it comes to vehicle safety and handling. On some models, the driver is able to choose a less assistive "sportier" mode when greater steering wheel resistance is preferred. Safety concerns are minimized as we still have the mechanical backup of the linkage system should we encounter a system failure.

We’ve come a long way from the early days of non-assisted steering to where we are today. As always, the initial costs will far outweigh economic gain while manufacturers retool to meet growing demand. The most profound retooling however may very well be driver perception.