PH Origins: Hydraulic power steering


For centuries, engineers have been using mechanical systems to augment human inputs. Gears, pulleys and levers have long served to grant our comparatively feeble forms significant mechanical advantage, permitting feats far beyond those which we could otherwise achieve.

As technology marched inexorably onwards, hydraulics, pneumatics, servos and more began to further aid our efforts. Ships, in particular, benefitted from these forms of assistance; during the 19th century, their weight and size increased rapidly - and accurately and quickly controlling the heavy, large ships and their vast rudders was becoming a significant issue.

In 1866, Scottish steam and marine engineer John Gray resolved the problem by designing a steam-powered 'steering engine' that could actuate a rudder. He also came up, more prominently, with an automatic control valve that would maintain the rudder in the desired position - making precise control of the vessel straightforward. This early self-correcting servomechanism was fitted to the SS Great Eastern and soon began being employed elsewhere.

Before long, similar systems were being developed by other engineers. Andrew Brown, a Scottish engineer known for his steam engine and hydraulic crane designs, later came up with a similar concept - called the 'steam tiller' - but expanded on Gray's design in 1872 with a system called the 'telemotor'.

This used pressurised hydraulic fluid to relay commands from the wheelhouse to the steering gear system, meaning that the complicated chain, cable or rope runs could be done away with - greatly simplifying the system and cutting weight and complexity. Telemotors would become standard-fit for decades to come and, even today, are often still fitted as a standby should a modern ship's electronically controlled systems fail.

Brown would later establish the Vauxhall Iron Works, too, which eventually became Vauxhall Motors - but the adoption of power-assisted steering in the automotive world was still some way in the future. In part, this was simply because there wasn't much necessity for it.


After all, the earliest cars were little more than glorified buggies - with rear- or mid-mounted engines - and their wheels were tremendously thin. They also often had large tillers, granting the driver a large degree of mechanical advantage; consequently, steering them didn't prove particularly problematic.

In the industrial and commercial marketplace, however, the story was somewhat different - because steam traction engines, for one thing, could be a real handful. American engineer George Fitts subsequently patented, in 1876, a method for using a power take-off from the vehicle's steam engine to steer in a commanding fashion what would otherwise be an ungainly, hefty traction engine.

All the driver had to do was simply move a lever back and forth; it would shift a pinion gear that would then engage with one of two pinions on the engine's crank. Drive would then be transmitted from the 'left' or 'right' pinion to the steering assembly at the front, quickly steering the steam vehicle.

Commercial vehicles - electric ones, in particular - were also beginning to need assisted steering. Trucks were still in their infancy in the early 1900s but electrically powered ones were quite common. They tended to resemble wagons, with no front overhang and the driver sitting directly over the front wheels, and the batteries were slung between the axles.

Unsurprisingly, these were heavy machines - with much weight on the steering axle - and when laden the wheels would be even harder to turn. As a result, electrically assisted steering was introduced to ease the driver's workload. The Columbia five-ton truck of 1903, for example, featured an electric motor to assist the driver's steering inputs. Four-wheel electric steering wasn't far behind; the Quadray all-wheel-drive electric truck of 1905, which weighed seven tonnes unladen, featured four-wheel electric steering.

English engineer Frederick Lanchester, who had already come up with numerous automotive innovations during the 19th entury, was also turning his attention to power steering - and in 1903 submitted a patent documenting 'Improvements in the Steering and Controlling Mechanism of Power Propelled Vehicles.'

In his patent, Lanchester described a pump which would circulate water - here's hoping a corrosion inhibitor would be used - through valves into a rotary drum assembly which would then operate the steering gear. Lanchester also explored the concept of using a cylinder and piston to damp the action of the steering gear, outlining a device that visually wasn't a million miles from modern hydraulic steering racks.

Lanchester's concept, like many others, lacked the backing required to develop it to fruition and was unfortunately destined to go no further. As was the case with Gray's steam-powered steering engines, though, similar designs began materialising in due course - including those based on compressed air and vacuum assistance.


Ultimately, it was American engineer Francis Davis who laid down the designs of what would become the first practical and mass-produced hydraulic power-assisted steering system. During the early 1920s, cars were advancing at a rapid rate and getting quicker, heavier and more capable - and using wider tyres to grant improved grip and traction. This meant that the steering ended up being overly heavy, making it a handful and tiresome to deal with over longer trips.

Some manufacturers countered heavy steering by fitting larger-diameter steering wheels and altering the ratios of the steering gear but this resulted in inaccurate, sluggish control. Davis, a talented and well-known engineer who worked at Pierce-Arrow until 1922, was also working on large trucks at the time - and had observed how hard to handle they could be - so he set about coming up with a method to alleviate these steering-related problems.

By 1926, engineer George Jessup had turned the power steering system designed by Davis into a reality - and the system was fitted into a 1921 Pierce Arrow roadster owned by Davis. The set-up featured an engine-driven hydraulic pump, which fed pressurised fluid into a hydraulic steering box.

It worked remarkably well and GM, on experiencing the system, signed a contract with him to use the system in its Cadillacs. Unfortunately, although a prototype was ready by 1933, the depression in America led to a prompt curtailing of the development of any expensive luxury-focused technologies. There was also some question from those above as to whether it was really necessary, while some had been less than impressed with the way that power steering felt on the road.

Not that the system was dead in the water, mind; British engineering firm Vickers, in 1928, reportedly began producing the system designed by Davis for various applications. Davis continued to develop his own system, too, submitting patents on numerous hydraulic steering innovations from 1927 onwards.

The vast Bendix Corporation then took on the power steering system - and was well positioned to do so, given its ties to myriad manufacturers. It managed to coerce another GM division, Buick, to take up the power steering system - but fate once again intervened and the start of World War II put civilian power steering systems on the back burner.

That said, rapidly escalating military demands and technological advancements meant that Bendix and Davis had plenty of business. Trucks, armoured cars, recovery vehicles and more all benefited from hydraulic assistance.

Even aircraft were beginning to adopt different forms of control assistance; by the 1930s, the Soviets were experimenting with electromechanical control surfaces for aircraft - and, by the early 1940s, hydraulics were being employed in the primary control surfaces of aircraft such as the Lockheed Constellation, Bell P-59, late P-38Js and the P-80.


After the war, as the economy in America boomed, power steering finally hit home in the civilian market when Chrysler unveiled its 'Hydraguide' power steering system for its Imperials in 1951. It offered a plethora of benefits; the power steering system required much less effort, for one thing, which cut fatigue. It also helped the driver maintain control of the vehicle by reducing 'wheel fight' while the hydraulic system would absorb some of the impacts transmitted from the road to the wheel.

'The most amazing mechanism ever designed for the automobile,' proclaimed Chrysler's power steering brochure from 1951. 'Just imagine turning the large 8.90 by 15-inch tyres on the Chrysler Crown Imperial - the largest tyres on any automobile today - their full travel from side to side while the car is standing still, with only one finger on the spoke of the steering wheel!'

The comparative lightness of power steering at lower speeds also made parking and manoeuvring around town far easier. Chrysler also simultaneously adopted steering gear that cut the number of lock-to-lock turns from 5.5 to just 3.5. Consequently, the cars also responded more quickly and were more nimble.

'Chrysler Power Steering is regarded as one of the greatest convenience and safety features - not only for women drivers, but also for men - that has ever been developed for the automobile,' claimed the advert. The irony was, alas, that the Chrysler system was based on expired patents from Davis that reflected the system used in his Pierce-Arrow back in 1926. As a result, Davis wasn't to get a dime from Chrysler's 'Engineering First'.

There was one saving grace: the system Davis had licensed to supplier Bendix was based on patents that still belonged to him, so he would receive royalties from any sales the company drummed up. It didn't need to try hard, either, as soon it was flooded with orders for power steering as the demand for this remarkable 'finger-light' steering system swept through the automotive marketplace.

Chevrolet followed suit in 1953, fitting power steering to more affordable cars - and, by 1956, Detroit was reporting that more than one in four cars was being sold with power steering. In that year alone, in excess of two million cars would roll off the lines with PAS. By March 1958, the likes of Mercedes-Benz had also started employing power steering in its 300.

Fortunately, Davis - now regarded as 'the father of power steering' - lived to see all this and more. He died in 1978, at the age of 91, long after his system had become a worldwide success.

P.H. O'meter

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