PH Origins: Cruise control

In the early 1930s, engineer Samuel G. Frantz noticed that inadvertent speeding was occurring more often on American roads. The issue appeared most prominent in areas that had both rough and smooth roads; drivers would abide by the limit on poor surfaces but on better roads build up speed 'without realising it'.

New technology was among the reasons for the rise in speeding, concluded Frantz. Suspension systems were getting more advanced, coping with bumps better, and engines were more refined and potent. Consequently, it was far easier for a driver to unknowingly achieve an 'excessive rate'.

The solution proposed by Frantz was a 'speed control device' that would allow a driver to more easily and efficiently maintain a vehicle's speed. It would need to be easily overridden, so the driver could take control when required, and function unobtrusively.

By January 1932, Frantz - who worked at electronics specialist RCA - had invented a series of concepts that fulfilled his criteria. In its simplest form, a governor-driven system would effectively nudge the driver's foot if the speed wandered from a predetermined value; more complicated versions could regulate fuel or air flow to further help maintain the right speed. One proposal even included a modification to a speedometer which would effectively add a 'target speed' indicator to its outside edge.

All required the driver to keep their foot on the pedal and couldn't function unassisted, but many basic cruise concepts - including overriding the target speed by accelerating - were established by Frantz. Seemingly, despite receiving a patent in 1937, he took his idea no further. This was presumably because, at the time, he was otherwise fully occupied establishing a new company to design and produce magnetic separators for industrial applications.

Later, in May 1942, fuel rationing was enforced in 17 states in America to aid the war-related demands on the country's resources. By the end of 1942, fuel was rationed in all 50 states. The rationing of this vital lifeblood wasn't driven by an outright requirement to just preserve fuel, however - it was also designed to cut down America's rubber consumption.

Because Japan had taken control of Southeast Asia's rubber-producing zones - which had previously supplied the Allies - America was sorely lacking in the rubber necessary for the production of military vehicles and equipment. Synthetic rubber production was limited, too, so ways to prevent wastage were quickly brought into play. Less fuel meant less civilian travel, for starters, reducing consumption of both fuel and rubber.

Similarly, a nationwide 'Victory' speed limit of 35mph was introduced to reduce both tyre and fuel consumption. Many disliked the lower limits, however, either finding them incredibly boring or difficult to stick to.

Engineer Ralph Teetor had - like Frantz - observed the inability of many drivers to maintain a constant speed. He was, in the early 30s, a partner of the American parts manufacturer 'Teetor-Hartley Motor Company'; it would later be rebranded 'Perfect Circle' and Teetor would become its president.

Teetor, reputedly due to the low 'Victory limit' that many struggled to maintain and the need to save resources, set about working on a speed control system. This was later stated by his daughter; the story was originally that Teetor, who had been blind since a young age, disliked the rocking motion experienced when drivers continually changed their speed - which motivated him to develop a speed control system.

It took some time for him to develop a reliable system, in any case, and he finally submitted a patent - which referenced Frantz's earlier work - in August 1948. It was granted two years later and, following several further years of development, the Perfect Circle 'Speedostat' was born. The first production set-up was introduced in 1957 and, in 1958, it graced the Chrysler Imperial - in which it was dubbed 'Auto-pilot'.

Like Frantz's earlier concept, the Speedostat offered haptic feedback. You chose your speed with a dial on the dash and, once reached, the pedal would stiffen to stop you accelerating further unintentionally. If you needed to go faster, you simply pushed through the 'barrier'. Or, if you wanted to take your foot off the pedal - a key feature of a modern cruise system - you would simply hit a 'hold' button. The road speed would be obtained from a sensor reading the rotation rate of the driveshaft, while an electric motor would vary the throttle position to maintain the target speed.

Other manufacturers soon began buying the Speedostat and rebranding it for use in their cars; Cadillac called it 'Cruise Control', Chevrolet 'Speed and Cruise Control', and both Lincoln and Mercury named it 'Speed Control'.

It is worth mentioning that both Frantz and Teetor's approaches were indirectly preceded by some older technology, including a set-up found in the Wilson-Pilcher automobile of the early 1900s - which featured a governor-controlled engine. This, effectively, would maintain a set engine speed and function as a rudimentary form of cruise control. As Teetor had observed, however, these set-ups had issues that included definite speed limitations, the requirement to disable the governor to exceed set speeds and a limited degree of flexibility.

Teetor's production cruise control system, with its driver-adjustable speed, easy override and no requirement for pedal applications resolved all of those issues. It was also praised for making long journeys less tiring, improving concentration on the road and, in some cases, reducing fuel consumption.

When the oil crisis of 1973 struck, manufacturers touted the fuel-saving potentials of cruise control systems - which were offered by several companies by this point - and the system subsequently flooded into the wider market.


P.H. O'meter

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Comments (65) Join the discussion on the forum

  • BFleming 05 Feb 2018

    My company sponsored an advanced driving course maybe a decade ago, and the instructor advocated the use of cruise control in almost any circumstances - urban driving, motorway cruising, driving in congestion. It took a little getting used to, but nowadays on 30mph roads, some that you would easily think should have 40 limits, I use cruise.
    And before anyone mentions the Winnebago cruise control lawsuit, there wasn't one! It's an urban myth that went viral, and isn't true!

  • tim milne 05 Feb 2018

    Surely the most interesting thing about this is that it's an easy thing to do with fly-by-wire throttle systems controlled by computer, but in fact originates in a far older, mechanical technology. Nowadays, it's a feature enabled by software a few cheap, generic buttons, which must cost, er, buttons, but it must have been costly to install in a sixties car

  • Swampy1982 05 Feb 2018

    another enjoyable read about the origins of something i use everyday, keep um coming!

  • Krikkit 05 Feb 2018

    tim milne said:
    Surely the most interesting thing about this is that it's an easy thing to do with fly-by-wire throttle systems controlled by computer, but in fact originates in a far older, mechanical technology. Nowadays, it's a feature enabled by software a few cheap, generic buttons, which must cost, er, buttons, but it must have been costly to install in a sixties car
    We had a late-90s Subaru Legacy with cruise, which made modern systems look a doddle.

    Under the bonnet was an electronically-controlled vacuum valve which operated the throttle linkage independently of the actual pedal - you could feel it adjusting the throttle as you drove along if you put your foot gently on the pedal. A very good system, but immensely complex compared to a DBW throttle system.

  • sticks090460 05 Feb 2018

    I use cruise control the whole time. I've never had a speeding ticket in 40 years of driving. I think these facts may well be related.

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