Braking for the third century

This article will be the first in a series, covering the development of road car brakes. In this first instalment, the development of the automobile, its powertrain and commercialisation will show why the need for reliable brakes became so obvious, but also that right the method of deceleration had many different interpretations, until competition and scale began to consolidate the technology. In researching the history of any technology, it can be difficult to separate the facts from the fiction, and so I have relied heavily on patent filings as primary source.

The age of invention – steam, electric and combustion engines

Fig. 1 : Josef Bozek and his steam-powered carriage

The history of the car owes a lot to the railway industry, and the invention of engines (either steam, electric, or eventually, combustion). In the early 1800s, steam engines were the dominant force in the transport industry, and so the first cars were adaptions of horse-drawn carriages, with steam engines. While the first steam car probably dates back to the 18th Century, with Cugnot’s three-wheeled “steam dray”, built in 1770, and intended to convey large artillery for the French army. However, roughly 200 years ago, two inventors working on different continents utilised the nascent steam technology for personal transport carriages (Czech inventor Josef Bozek in 1815, and American inventor Thomas Blanchard in 1825). While they didn’t achieve overnight success, they blazed a trial for further inventors and industrialists to enter the fray. These machines were the first to achieve commercial success, but while this happening, several other really important technologies were being invented (the electric motor in 1828, rechargeable lead-acid batteries in 1859, the four-stroke IC engine in 1864, the four-stroke compression IC engine in 1876, the two-stroke IC engine in 1879 and the diesel IC engine in 1892).

So while the format of the first automobile was being worked around a steam engine, a whole host of drivetrain possibilities sprang up, each being pursued by new companies and visionaries.

Most road vehicles available in the 1880s were limited to short ranges, and achieved relatively low speeds (up to 30km/h), meaning they were used mostly in urban areas.

The worlds’ first brake durability test (and failure)

In 1886, Karl Benz patented the world’s first internal combustion-engined automobile, the Patent-MotorWagen 1. However, it wasn’t until August 1888, when his wife, Bertha, (reputedly unbeknownst to her husband) undertook the world’s first road trip in Patent-MotorWagen 3 (where did they think up the names?…) that road car brakes proved themselves a necessary technology in their own right. During this inaugural long distance road test from Mannheim to Pforzheim, Bertha had to stop off for refuelling, repairs to fuel and electrical systems, and to have the vehicle’s brake shoe leather coating replaced.

Fig. 2: Benz PatentWagen Nr.3 – with brake shoe acting on rear wheels.

While the road trip itself garnered much attention, it also lead to adaptions of the vehicle design, including a second gear ratio, and better brakes (!)

The design of brake for Benz’s PatentWagen is common to many vehicles of the day. The other major braking technology employed is the band brake, which begins to dominate designs once rubber tyres become common. The band brake can be applied in-board, often wrapping around a transmission component, or outboard, as part of a wheel hub design. This transmission brake design was employed in the first mass market vehicle, the Model T from Ford.

The need for speed

If the predominant brake of the late 19th century was not much more complicated than that of a home-made go kart, the slow speeds of the day meant this provided enough retardation. But throughout the 1890s, more powerful motors and higher vehicle speeds meant braking innovation began in earnest. Work begins on disc brakes and drum brakes, and at the turn of the century, both are ready for the limelight.

The 1890s sees the dawn of racing as a popular format, with inaugural races been run in Europe (Paris to Rouen) in 1894 and America (Chicago to Evanston) in 1895. By the end of the decade, closed circuit races are established, and international racing trophies are being muted.

In 1898, the first land speed record was recorded – 63km/h. A year later, a dedicated attempt succeeded in achieving 105km/h, being the sixth such record, and to date, all with electric vehicles. In 1906, a steam-powered Stanley Rocket achieved 205km/h.

A British engineer, Frederick William Lanchester, patented the first disc brake in 1902, which were eventually sold on cars bearing his name. This was a thin metal disc fixed to the wheel axle, and a copper “pad” mounted on a pair of gripping jaws. As such, Lanchester likely also discovered the world’s first brake squeal – although that feature didn’t make it to the patent application!

Fig. 3: Patent drawings of first disc brake

Brake noise in disc brakes was a significant drawback, and this lead to the pad designs from asbestos, starting in 1907. Asbestos was still a significant component in brake pad linings for the next 80 years, and copper is still in use in pad linings today.

Disc brakes didn’t really flourish at the time, which is mainly attributed to their inability to deal with the environmental conditions of the day (roads weren’t much more than compacted dirt in many areas), and they spent a long time as a novelty, before reaching wide-scale acceptance in the late 1950s.

Around about the same time, drum brakes were being developed, and again in 1902, the first patent for a drum brake was registered, by Louis Renault, one of the three founding brothers of Renault Motors, whose regenerative brakes we covered in an earlier article. Such internal drum brakes had a number of advantages over contemporary approaches – the drum housed the braking surface, protecting it from the environment, the braking effect was multiplied by the geometry, meaning significant brake power could be achieved, and the design showed good tolerance of thermal load.

Fig. 4: Extract from Renault’s 1902 drum brake patent

A bolt from the past

Speaking of regenerative brakes, predating these two inventions by some years was the work of another french inventor/engineer, Louis Krieger. His work focused mainly on electric vehicles and while he wasn’t alone in this at the time, his approach was unique in locating electric motors directly attached to the driven wheels. His 1896 patent shows a novel arrangement of motors attached to both front wheels, with a single power regulator circuit to synchronise the rotational speed, allow for speed differential as a means of steering, and braking torque to be applied to the motors in order to recharge the battery if so desired.

Fig. 5: Krieger’s FWD dual motor electric drive arrangement.

This is a technical marvel, and an extraordinary development in today’s terms – torque vectoring and regenerative braking in one system, combined with a control system allowed for dual battery voltages – offering a low speed, high range “eco” mode, and a high speed, low range “sport” mode.

In 1896!

Krieger went on to develop a petrol/electric hybrid, as well as pioneering significant motor control improvements, vibration controls, tyre valving, battery cooling, gearbox and drive shaft improvements, and a host of related technologies. His development ideas were recreated a few years later by Ferdinand Porsche, whose first cars were similar in concept to Krieger’s, built with the Lohner coach company.

Fig. 6: Krieger Brougham from 1904.

The power of hydraulics…

Malcom Lockheed’s hydraulic brakes were already in use before the his initial patent in 1917, being offered commercially on cars from 1914, and well established in trains and tractors. However, his vision was to utilise the flexibly of supply hoses together with the advantage of hydraulics to greatly improve the brake power that a driver could achieve compared to levers and linkages. His patent filing also showed a single hydraulic plunger acting on all four wheels simultaneously, although the adoption of four wheel braking was already known from racing vehicles, and some short-lived passenger vehicles. Lockheed (or Loughead as per the original spelling) went on to devote his energies to aircraft design.

Fig. 7: Lockheed’s hydraulic four-wheel brake design

Reviewing the first century of brakes

In the initial century of road vehicles, a lot of ground has been covered. In particular, the 4 decades covering 1880 to 1920 see the transition from engineering vision to burgeoning mass production, which in turn emboldens armies of inventive types to throw their lot into the booming car market. Vehicles speeds have increased dramatically, and therefore the importance of reliable brakes becomes paramount. The building blocks of todays brakes were well established, and some ideas that were centuries ahead of their time have since become relevant again.

Fig 8: Overview of brake technology developments from 1820 to 1920

I’ve highlighted a couple of the more important inventions in terms of brakes, and tried to provide the context under which they came about. In the next instalment, I will concentrate on the convergence of technology into something more recognisable today, as well as the sharp rise in brake control technology.