The first automobiles weren’t terribly big and steering them was relatively easy with the large steering wheels of the day. When cars started to grow in size and weight, however, muscling the steering wheel around started to require some real strength. The car manufacturers knew this was a problem and many proposed “powered” steering solutions. Soon different manufacturers prototyped vacuum, mechanical, and electrical power-steering systems but none worked well enough to make it into production. One engineer, however, was convinced that hydraulic power steering was the answer and continued to work on it. His name was Francis W Davis.
Who was he?
Francis W Davis was a Harvard trained mechanical engineer. In 1906, he went to work for the prestigious Pierce-Arrow company and was put into the group that worked with the sheet metal molds. Since these molds were all controlled by hydraulic technology, he soon became an expert in the field. He left the company in 1922 to become a consulting engineer with a specialty in hydraulic systems.
Burning the midnight oil
Davis knew that he could design a practical hydraulic-powered steering system if given enough time. The challenge for him was to make the technology small enough to be used in a car. The problem was that the existing “pressurized hydraulic systems” needed large storage tanks of pressurized oil and were complex with components such as pumps, unloader valves, accumulators and lots of heavy-duty hose lines.
After much work miniaturizing pressurized systems, he had a brainstorm. Rather than use a standard closed valvepressurized system, he developed an open-valve system that allowed hydraulic fluid to flow continuously, but when power-steering assistance was needed it was closed and pressure was allowed to build up. This would allow a much simpler, more compact solution.
Davis prototyped his new system and installed it in his 1925 Pierce-Arrow Roadster. Not only did it make the car easy to steer, it also removed any road vibrations that would feed through the steering wheel to the driver’s hands.
It also addressed the problem of steering reversibility, as Davis described it. This is when a car hits an obstacle and the force is transmitted to the steering wheel -sometimes causing the wheel to be wrenched from the driver’s hands. Davis solved this by making his system adjustable so it could be built with a degree of reversibility; the maximum torque that could be impressed on the steering wheel by road shocks was limited to a predetermined value.
The great depression
Davis’s design was ingenious but the depression of the 1930s meant that few car manufacturers were interested in licensing the technology. Len Stoler of Westminster, MD, a full Chrysler, Dodge, Jeep Ram dealer, pointed out to us that when the car market picked up after the Second World War, Chrysler was the first company to introduce a hydraulic power-steering system on its flagship Imperial sedan in 1951.
Industry wide adoption
It only took a few years but by the mid-1950s most of Detroit was offering power steering on their cars. In fact, by 1956, more than two million vehicles had been sold with power steering. Thanks to Davis’s persistence, the power steering technology in one form or another is used in just about every automobile made today.