35 hp Mercedes: First Daimler car with propeller shaft drive
Beginning of the end for the chain drive
Robust and lightweight mechanics
In the spring of 1908, Daimler-Motoren-Gesellschaft (DMG) launched the new 35 hp model – Daimler’s first car with propeller shaft drive. This type of power transmission from the gearbox to the driven axle via a shaft with universal joints was the most important innovation of the new Mercedes model. The engine, by contrast, was adopted in almost unmodified form from the previous 35 hp model with chain drive. It consisted of two rows of cylinder pairs arranged in line, and it had lateral camshafts and upright valves.
From 1908, the 35 hp model advertised as “cardan car” ushered in the gradual replacement of power transmission by chains between engine and axle at DMG. However, chain drive was to remain in the range of the Stuttgart-based manufacturer, parallel to propeller shaft drive, for several years to come. In particular, heavy and powerful cars continued to be fitted with chain drive which was considered to be more comfortable.
From belt drive to propeller shaft
Propeller shaft drive, today the standard in automotive engineering, was one of three alternatives in the early days of the automobile, alongside belt drive and chain drive. In Daimler’s motorized carriage of 1886, power transmission was still performed by both a flat belt (from engine to countershaft) and chains (on to the ring gears on the rear axle). The engine of the wire-wheel car of 1889 even acted directly on the rear wheels. In 1895, finally, Daimler’s belt-driven car made its debut. In this car developed by Wilhelm Maybach, a belt transmission conveyed the power of the rear-mounted Phoenix engine to the rear wheels.
The Daimler Phoenix of 1897 was the first chain-driven automobile developed by Maybach and Daimler. DMG had already been offering the so-called Schroedter car with chain drive since 1892, but this car was built at a time when Maybach and Daimler worked at the Hotel Hermann, independently of DMG. In the following years, chain drive became the standard for transmitting power from the gearbox to the axle.
Robust lightweight design with little comfort
The rather hesitant advance of propeller shaft drive as the successor to chain drive was due to mechanical problems in the first years of the 20th century. Power transmission by means of an axis with universal joints at one or both ends was convincing in that it was robust, light and largely maintenance-free, but the clearly stiffer connection between axle and engine as compared to the chain caused strong vibrations which adversely affected ride comfort for the passengers.
The advantages of the new technology prevailed eventually, and numerous manufacturers started to build car with propeller shaft drive at the turn of the century. In this respect, Benz & Cie. was five years ahead of DMG. As early as 1903, the Benz Parsifal was the brand’s first car with propeller shaft drive to come onto the market. Alongside the two-cylinder models with 8, 10 and 12 hp (5.9, 7.4 and 8.8 kW) and propeller shaft drive, the range also included a 16-hp four-cylinder model (11.8 kW) with chain drive. Continuous further development of the propeller shaft drive ensured growing acceptance for this type of power transmission.
Development of the Mercedes “cardan car”
After the debut of the 35 hp Mercedes with propeller shaft drive in 1908, the car was given a new model designation – 21/35 hp – in 1909. The first figure indicates the tax horsepower, the second figure the actual power output from a displacement of 5.3 liters. In the following year, stroke was increased to boost the output of the successor model to 22/40 hp from a displacement of 5.6 liters. Displacement was enlarged once again – to 5.7 liters – in 1913. The car, now designated 22/50 hp, was powered by a four-cylinder in-line engine with cylinders arranged in pairs and developing 50 hp (37 kW).
Initially, propeller shaft drive was used only for the lighter models at the lower end of DMG’s spectrum. In 1910, finally, not only the 22/40 hp Mercedes was launched but also a larger and more powerful model with propeller shaft drive, the 28/50 hp. Its four-cylinder in-line engine developed 50 hp (37 kW) at 1200 rpm from a displacement of 7.2 liters. In 1913 output rose to 60 hp (44 kW) at 1300 rpm, and the designation correspondingly changed to 28/60 hp.
The 28/50 hp (later 28/60 hp) was available with either propeller shaft or chain drive from early 1912 until 1914. The same applies to the 22/40 hp (later 22/50 hp). Of this model, however, only a special version – a camper or colonial car – was offered for poor roads and rough terrain. The characteristic feature of the camper or colonial car was it higher ground clearance and larger track width.
Expansion of the range
One year after the market launch of the 35 hp Mercedes with propeller shaft drive, the 15/20 hp model followed in May 1909, complementing the range as an inexpensive entry-level model with propeller shaft drive. When displayed at the Paris Motor Show in December 1908, the 15/20 hp still had a conventional four-cylinder engine with upright valves. The production version of 1909, by contrast, featured a more advanced design with pendant intake valves.
The designation of the 15/20 hp model (the first figure indicating rated output, the second the actual output) was modified in 1909 analogous to the renaming of the 35 hp model. The smaller car with propeller shaft drive was now called the 10/20 hp, with the first figure indicating the tax horsepower calculated on the basis of displacement. From June 1913, the 2.6.liter model was known as the 10/25 hp Mercedes. Its engine developed 25 hp (18 kW) at 1600 rpm.
The 14/30 hp model was another car with propeller shaft drive which in terms of its design corresponded to the 10/20 hp. It was launched in 1910 and had an engine with 3.6-liter displacement. This engine developed 30 hp (22 kW) at 1600 rpm. In mid-1913, output rose to 35 hp (26 kW) at 1700 rpm, and the car was renamed 14/35 hp model.
Chain drive retained for large automobiles
The 28/50 hp (28/60 hp) model was a mid-sized model in the Mercedes sales lineup, with the other cars with propeller shaft drive ranging below it. In the upper market segment, DMG continued to use chain drive. In 1910 the 38/70 hp Mercedes – a luxury car – was made available with chain drive only. It had a nine-liter engine with two pairs of cylinders, lateral camshafts and upright valves. It was renamed 38/80 hp model in June 1913.
The new Mercedes top model, the 37/90 hp launched in June 1911, equally had chain drive. This new high-performance car featured a four-cylinder engine with three-valve technology and dual ignition. It replaced the six-cylinder models built from 1907. A special innovation was the design of encapsulated drive chains running in an oil bath. Despite this advance, chain drive was doomed to obsolescence: the 37/90 hp was the last newly developed car with chain drive from Daimler-Motoren-Gesellschaft.
Eponym of “cardan drive”
Daimler-Motoren-Gesellschaft consistently referred to “cardan cars”, named after the Italian mathematician, philosopher and physician Gerolamo Cardano (1501 - 1576). Cardano was the first author of the early modern period to describe the suspension of measuring devices in a system of movable rings – a principle that had been known since antiquity and was named after Cardano at a later stage. The universal joint, based on similar mechanical principles, was equally named after Cardano even though it was not invented by the Italian mathematician.