#284 Duesenberg 4-Wheel Hydraulic Braking System
Frederick S. Duesenberg was the first to use four-wheel hydraulic brakes on a production automobile. He also invented and employed internal expanding-shoe hydraulic brakes on his vehicles. These braking innovations were first featured on the Duesenberg Model ‘A,’ which was introduced in 1921. Duesenberg Automobile and Motors Company had been established only the year previously.
Providing hydraulic brakes on all four vehicle wheels significantly reduced braking distances, which became increasingly important as vehicle speeds increased. All automobile companies eventually introduced four-wheel hydraulic braking systems, although some not until over a decade after Duesenberg.
Mechanical engineering concepts, features and characteristics
In hydraulics-based systems, mechanical movement is produced by a contained, pumped liquid, typically by means of cylinders that contain moving pistons. The mechanical engineering principals are well-known.
All hydraulic systems work on the principle of Pascal’s law, which states that any increase or decrease in pressure in an incompressible fluid will be transmitted equally in all directions in a static fluid.
The wheel cylinder of Duesenberg’s hydraulic drum brakes (10 o’clock position below) acts as a hydraulic press. The pressure in the input line from the brake actuator (usually a pivoted pedal) is transmitted by an incompressible fluid (the brake fluid) contained in a supply line and exerted on the wheel cylinder piston(s). The force is multiplied by the ratio of the area of the cylinder to the area of the actuator piston.
Left: Illustration of brake mechanism from Duesenberg’s patent application. US Patent 1,490,163 filed November 16, 1920.
Besides the multiplication of force achieved, Pascal's law states that the pressure is transmitted equally to all parts of the enclosed fluid system. This provides straight-line braking unless there is a fluid leak or something to cause a significant difference in the friction of the surfaces.
An important requirement is that the hydraulic liquid used in the brake system cannot be compressed. Since air is compressible, a hydraulic system must be free of air in order to function properly.
Competing Braking Systems
While the Duesenberg Model ‘A’ was the first commercially produced automobile to use four-wheel hydraulic brakes and internally expanding-shoe hydraulic brakes, Malcolm Loughead had previously invented a hydraulic automobile braking system for four-wheel applications. Loughead’s brakes, however, were external-contracting band brakes and were not introduced in production quantities until late 1923 — two years after Duesenberg introduced his hydraulic braking system.
Moreover, neither Malcolm Loughead nor Fred Duesenberg could claim the invention of four-wheel brakes or the hydraulic brake.
- The first known use of four-wheel automotive brakes is due to Henri Perrot, a Frenchman working for Argylls Ltd., manufacturer of the Argyll automobile in Alexandria, Scotland. Perrot filed for a US patent covering a four-wheel brake system – which used mechanical rather than hydraulic linkages -- on January 14, 1913, and US patent 1,076,311A was issued October 21 of the same year. The 1912 Argyll 15 HP was the first car equipped with Perrot’s brake system.
- The honors for the invention of the hydraulic brake may belong to Frederick Henry Royce, however, it does not appear that his hydraulic brake was ever manufactured. It certainly was not introduced on a production automobile prior to the Duesenberg. There are reports that Knox Motors Co. used hydraulic brakes on the rear wheels of a truck tractor in 1915.1
- The Triumph 13/35 was the first to offer hydraulic brakes in the United Kingdom in 1924. The Adler ‘Standard 6’ of 1926 was the first vehicle to use hydraulic brakes on Continental Europe.
The Landmarked Vehicle
The restored 1926 Duesenberg Model ‘A’ chassis (in operable condition) in the Auburn Cord Duesenberg Automobile Museum recognizes Duesenberg’s landmark achievement. A chassis without an automobile body mounted is especially appropriate, since Duesenberg only manufactured chassis assemblies for the Model ‘A.’ Automobile bodies were custom built by some of the finest coach-builders of the 1920s and added later. It is also appropriate because the components of Duesenberg’s innovative hydraulic brake system are more exposed and viewable by the public in this form.
1 “Newly Designed Knox Tractor Has Hydraulic Brakes,” Motor Age, March 4, 1915, p. 32.
This image shows one of the vehicle’s wheels, including its brake drum. Duesenberg’s hydraulic brake system used internal expanding-shoe hydraulic brakes.
The vehicle’s dashboard displays the hydraulic brake pressure.
The landmark 1926 Duesenberg Model ‘A’ chassis was previously owned by some important vintage automobile collectors. It was restored by Al and Dottie Bennett for the late Homer Fitterling of South Bend, Indiana. The chassis was later sold to the noted Duesenberg collector Ed Weaver. Before being sold, the chassis was publicly displayed in the 1995 ACD Labor Day Reunion Meet, where it also participated in the Annual Parade of Classics. Before coming to the Auburn Cord Duesenberg Automobile Museum, it was displayed in a private museum.
Although this chassis is assembled from parts, all of the parts are original Duesenberg Model ‘A’ components. This car retains an original Duesenberg firewall tag, which labels the chassis as car number 765 and the engine as number 1164. It should be noted, however, that this engine is number 1010 and does not match the number on the build plate.
The 90-horsepower Duesenberg overhead camshaft engine is complete and retains its rare, original Schebler Model S updraft carburetor, as well as its original ignition system, water pump, manifolds, starter, and generator. The radiator has its original honeycomb-style core and is fitted with an original Duesenberg Model ‘A’ radiator shell.
Specifications, including technical description and data.
Fred Duesenberg described his hydraulic braking system in two patent applications — US 1,490,163 and US 1,703,483, both filed on November 16, 1920. The first provides a “plan of a motor car chassis equipped with a brake system exemplifying (his) invention.”
Duesenberg notes his “invention contemplates the use of a suitable fluid, such as oil, for the operation of all four brakes under the control of a single actuating member conveniently located for operation by the driver. In the present example, the actuating member is a pedal, fulcrumed on a pivot, and suitably connected as by a link with a master piston working in a master cylinder.”2
2 The item numbers are omitted from the patent language, for clarity.
Both patent filings include identical illustrations of the hydraulic drum brakes:
In US Patent 1,490,163, figure 3 shows the front-wheel drums, and figure 4 the rear drums.
In his patent application, Duesenberg describes the operation of his braking system: “Referring to Fig. 5, each of the front wheel brakes is provided with a brake cylinder 146, having a piston 148 working therein, one pivotally connected at 150 to one of the brake terminals 70, and the other pivotally connected at 152 to the other brake terminal 72. Similarly, each of the rear wheel brakes (see Fig. 4) is provided with a brake cylinder 154 and a piston 156 working therein, one pivotally connected at 158 to the brake-band terminal 96, 110 and the other pivoted at 160 to the other brake-band terminal 98. Thus it is evident that the brake cylinders and pistons are supported jointly by the brake-band terminals, and as they are mounted within the 115 circumferential limits of the brake-drums, they are afforded protection by the latter, and the brakes moreover present a more sightly appearance.” … “The brakes are retracted by suitable springs 162 and 164, herein interposed between the pistons and the adjacent ends of the cylinders.”
Additional illustrations from the patent application:
The Auburn Cord Duesenberg Automobile Museum
The Auburn Cord Duesenberg Automobile Museum is a not-for-profit and educational institution owned by the non-profit Auburn Automotive Heritage, Inc. The organization was formed in 1969 by local volunteer leaders with contributed funds. The museum opened to the public July 6, 1974.
As the name suggests, the museum is dedicated to preserving automobiles built by the Auburn Automobile Company and Duesenberg Motors Company/Duesenberg, Inc.
The museum occupies the former Auburn Automobile Company Administration Building. It was part of the campus where cars were hand-assembled, rather than mass-produced. The Showroom and administrative building was designed by architect Alvin M. Strauss in the Art Deco style and built in 1929-1930. The facility's Showroom and administrative buildings, as well as the service and new parts building and the L-29 building were together declared a National Historic Landmark in 2005 and are listed on the National Register of Historic Places.
The museum is organized into seven galleries that display over 120 cars and related exhibits, such as the restored Auburn Automobile Company offices.
