by Adrian-Liviu Dorofte

Fire protection under the three-pointed star: The history of Mercedes-Benz fire-fighting vehicles and their predecessors - PART II


Stuttgart, Germany, Jan 01, 2007

Fire-fighting vehicles of Benz & Cie. and the Daimler-Motoren-Gesellschaft : 1906 - 1925

The Grunewald model: the first fire-fighting vehicle with gasoline engine – from Gaggenau

The first gasoline-engined fire-fighting vehicle in Germany went down in history as the "Grunewald model". On December 1, 1906, the voluntary fire brigade of Grunewald, an exclusive residential area of Berlin, started operating the vehicle with gas-powered extinguisher. The engine and chassis were supplied by Süddeutsche Automobilfabrik Gaggenau (SAF) which was taken over by the Benz company in Mannheim soon afterwards. The superstructure was manufactured by Messrs. Busch-Bautzen, the leading producer of fire-fighting equipment at the time.

Three engine versions with 18/22, 24/32 and 35/40 hp were offered by SAF. With the most powerful engine, the vehicle reached a top speed of 35 km/h and was able to climb gradients of up to 16 percent. The gasoline engine had thus proved its competitiveness: before this time, a comparable climbing ability had only been achieved by a fire-fighting vehicle with gasoline engine and four electrical wheel-hub motors, operated by the professional fire brigade of Elberfeld, today a part of the city of Wuppertal.

Daimler produces the first fire-fighting vehicle with gasoline engine for the professional fire brigade of Frankfurt

Frankfurt, December 1, 1907. Exactly one year after the voluntary fire brigade of Grunewald, the first professional fire brigade in Germany took delivery of a fire-fighting vehicle with gasoline engine. It was a gas-powered extinguisher mounted on a 1.5 ton Daimler chassis with 28/32 hp four-cylinder engine. The superstructure including a 300-liter water barrel was also manufactured by the factory in Marienfelde; the equipment was compiled by the Frankfurt fire brigade itself.

It was thanks to Daimler's gas-powered extinguisher and the commissioner of the Frankfurt fire brigade, Johannes Schänker, that the reservations of fire brigades concerning gasoline engines were gradually dispelled. "When a fire-fighting officer hears of an explosion engine, he already knows for sure that it is absolutely useless for him," was the ironic comment of Otto Sander in 1906, later to be appointed commissioner of the Hamburg fire brigade. Apart from safety concerns, which were seemingly confirmed by leaking gasoline lines, setting engines on fire during assignments, people feared "that one couldn't be sure the vehicle would start under all weather conditions," as a Mr. Keller, commissioner of the Dresden fire brigade, objected at a convention of the German fire brigades in Stuttgart.

In an attempt to overcome such notions based on hearsay, Schänker endeavored to prove the reliability of the gasoline-engined vehicle by sending the Daimler fire-fighting vehicle from Frankfurt to Stuttgart. The vehicle traveled in pouring rain but in spite of this arrived in time for the convention after a seven-hour journey without a hitch.

One year later, the DMG customer magazine "News about Daimler trucks" reported on the practical experience gained by the professional fire brigade in Frankfurt:
"Some 3,000 kilometers have been covered on 145 trips to date – of these 174 kilometers on 19 trips to fires. Quite apart from being ready for operation much more quickly and leaving much earlier after an alarm than the horse-drawn vehicles, the motor vehicle arrived at the scene of fire up to five minutes earlier than the other fire-fighting vehicles. An advantage that paid off repeatedly in fire-fighting and rescue work."

In the same article, Daimler-Motoren-Gesellschaft announced:
"By installing a switchover clutch, we are able to use the upper drive shaft in the transmission box for directly driving a pump mounted on the frame, a ladder or any other mechanism.
This provides the possibility of using the engine, which drives the vehicle, for operating pumps and ladders directly. The vehicle drives to the scene of a fire, and the power of the running engine can be switched over to operate equipment."

A gasoline engine for driving both vehicle and pump

One year later, a major milestone was set when the Daimler factory in Marienfelde supplied the professional Frankfurt fire brigade with the first fire-fighting vehicle whose gasoline engine powered both vehicle and pump. "Initially, a piston pump directly driven by the vehicle engine was considered as replacement for the steam-powered pump, but this idea was soon discarded again," wrote Otto Bischoff in a special publication of Daimler-Motoren-Gesellschaft in August 1909. Instead, the engineers' attention was drawn to the newly developed centrifugal pump by English and French trade journals, and:

"It was by coincidence that Messrs. G. Schiele & Co., Bockenheim-Frankfurt a. M., discovered an excellently designed centrifugal high-pressure pump. Commissioner Schänker had commissioned Messrs. Schiele to test a conventional centrifugal high-pressure pump. These tests immediately proved the suitability of the pump for fire fighting because spray ranges of up to 75 meters and heights of 35 meters were reached."

The completed pump even exceeded expectations: with a suction height of 7.80 meters and three centimeter thick steel pipes, the water jet reached heights of around 50 meters – as documented by photos which appeared in a Daimler brochure. Alternatively, up to eight hoses could be connected, each reaching a height of 35 meters. In this way, the pump was capable of dispensing 1,800 liters of water per minute. In addition, the vehicle carried a 300 liter water tank for first intervention. A five millimeter thick water jet was sprayed 12 to 15 meters high during the first five to eight minutes, until the other hoses were connected.

The engineers were, however, a bit concerned about engine cooling in the stationary vehicle. Channeling part of the fire-extinguishing water through the vehicle radiator proved to yield highly satisfactory results: "The engine remained perfectly cool and worked evenly for hours on end, without being strained excessively." At the same time, engine heat prevented the pump water from freezing in winter.
Otto Bischoff continued by announcing the development of a ladder carrier and then wrote:

"The pump water tender easily replaces the steam-powered extinguisher, implement and crew carrier (not to mention the gas-powered extinguisher). The separate ladder carrier can carry another eight to ten people, and these two vehicles bring a complete and fully operational combination to the scene of fire quickly, at a brisk speed of 30 km/h. When it comes to fighting fires at more distant locations in large cities or supporting local fire brigades in more distant towns, there is currently no equipment that is more effective and more efficient that the combination of Daimler frame and gasoline engine with Schiele turbine pump plus Daimler frame and gasoline engine with mechanical ladder – no matter what type."

The second motorized pump water tender from Daimler was powered by a 36/42 hp engine. "An output of 28/32 hp may have been sufficient but DMG wanted to be on the safe side" (Bischoff). This caution related above all to pump output since little practical experience had been gained in this field at the time. A speed of 30 km/h was not to be exceeded anyway, given the road conditions at the time and solid rubber tires. But the more powerful engine had its advantages, for instance the vehicle's climbing ability of twelve percent.

The beginning of many years of cooperation: fire tender from Metz

At the same time, Süddeutsche Automobilfabrik Gaggenau, meanwhile a Benz factory, also started equipping pump water tenders with centrifugal pumps, operated by the engine via a separately engaged power take-off on the transmission. The partner of SAF was Messrs. Metz, founded in 1842 and at the time located in Karlsruhe.

Brothers Alfred and Karl Bachert, the managing directors of the company since 1905, had occupied themselves with the centrifugal pump since 1907. A chassis from Gaggenau with 45 hp engine was finally selected as the backbone for the first modern pump water tender, equipped with a 750 liter tank mounted in the center of the vehicle and a centrifugal high-pressure pump from Messrs. Sulzer. The pump operated at two stages, delivering 600 and 800 liters per minute at six or eight bar atmospheric pressure, respectively. When the tank was empty, the pump sucked water from a hydrant or inshore waters.
At the 17th convention of the German fire brigades in Nuremberg from July 24 until 27, 1909, the Bachert brothers presented their motorized centrifugal high-pressure fire pump. Soon afterwards, on December 15 of the same year, such a pump proved its capabilities in a large fire in Karlsruhe. The local press was impressed:
"The motorized pump water tender, equipped with an engine from Gaggenau, was in operation yesterday uninterruptedly from 10:45 until 4:45 hours and sprayed water into the raging fire through four mighty hoses at a pressure of six to seven bar (up to 40 or 50 meters high)."

Apart from pump water tenders, Gaggenau also produced crew carriers right from the start. As a leading motor manufacturer, the factory also endeavored to contribute to progress in fire fighting with technical innovations. A new ignition system from Bosch accelerated the starting of the engine. Soon afterwards, pneumatic tires became available at least for the front axle. With this equipment, the vehicles reached top speeds of around 35 km/h.

Fire-fighting vehicles and high-speed pump water tenders for rural fire-fighting on Daimler chassis at an early stage

The motorized Daimler fire engine of the Frankfurt fire brigade carried a 300 liter water tank; Metz opted for a 750 liter tank. As early as 1909, the Lübeck fire brigade owned a fire-fighting vehicle on a Daimler chassis with 2,000 liter tank and a centrifugal pump which was capable of delivering up to 2,400 liters per minute. At the time, the 50 hp four-cylinder engine was a top-ranking power unit.

Even commissioner Reichel in Berlin, a declared skeptic where the use of gasoline engines by fire brigades was concerned, was unable to escape the fascination of Daimler's gasoline engines. On the basis of a modified truck chassis, he had a fire tender with a rotational pump set up – this vehicle was not intended for inner-city operation but rather for rural areas. Bosch's double ignition was standard equipment by now, and engines developed between 32 and 50 hp. The most powerful engine gave the rural fire tender a speed of 40 km/h. The fire brigade commissioner personally performed two trial journeys with these vehicles in 1911, covering more than 1,000 kilometers.

Motorized turntable ladders from Gaggenau and Marienfelde

Alongside pump water tenders, crew and equipment carriers, turntable ladders are indispensable aids for the fire brigades. Great progress had been made in the development of retractable ladders in the 19th and early 20th centuries. One of the pioneers was Conrad Dietrich Magirus who climbed hitherto inconceivable heights – up to 23 meters – with his "Ulm ladders" in 1872 and four years later with his own patented development. In 1901, his company presented another innovation which was to be widely used from then on, namely a patented turntable ladder extended with carbonic acid pressure.

And so Magirus was selected as a supplier when the first combination of three fire-fighting vehicles powered entirely by gasoline engines in Germany was to be equipped with a turntable ladder for the professional fire brigade of Breslau in 1910. The chassis of the pump water tender, turntable ladder and equipment carrier came from Daimler's factory in Marienfelde. However, the turntable ladder was not yet driven by an engine – contrary to what had been announced as early as 1909. Ulm-based Messrs. Magirus, which at the time had not yet started producing trucks, developed a ladder powered by the vehicle engine only three years later, again in collaboration with the Marienfelde factory. The 22 +3 meter high turntable ladder was put into operation in Görlitz in 1914.

Turntable ladders were also developed by the Bachert brothers at Metz. Their first turntable ladder powered by a gasoline engine was mounted on a Benz chassis from Gaggenau in 1912. Stability was ensured by a track width enlarged from 1.50 to 1.74 meters. This ladder, too, was extended by carbonic acid pressure. But as early as 1913, Alfred and Karl Bachert applied for a patent for their engine-powered turntable ladder. The resulting vehicle, equipped with anti-tilt device, automatic balancing and an engine that extended and turned the ladder, was not built until 1923 due to the First World War.

The gasoline engine succeeds

The gasoline engine did not prevail over its competitors immediately, far from it. But the pioneering decisions made in Berlin-Grunewald and Frankfurt, Marienfelde and Gaggenau soon brought about a significant increase in fire-fighting vehicles with gasoline engines.

In 1908, there were no more than ten gasoline-engined fire-fighting vehicles in Germany – as opposed to 20 steam-powered and 24 electrically driven units. Five years later, the gasoline engines – 117 of them – were already the largest contingent, followed by 90 vehicles with battery-electric drive. The 16 steam-powered pump water tenders were already somewhat advanced in age, whereas the mixte drive – with just 22 vehicles – played a subordinate role.
Of the 117 gasoline-engined vehicles operated in 1913 by German fire brigades, 70 had been produced by Daimler. Two years later, the figure had grown by another 30.

Beyond German borders

Hardly had the gasoline engine joined forces with the centrifugal pump did the Daimler factory in Marienfelde start supplying vehicles to distant countries. In 1908 a motorized pump water tender with Schiele pump and a crew and equipment carrier were supplied to Moscow. At 85 hp, the engines were clearly more powerful than was customary in Germany at the time.
Gaggenau exported a motorized fire engine to Budapest as early as 1910. Two years later, the Benz factory published its export successes: Koloszvar, Ixelles and Kasan were the names of the towns where fires were fought by vehicles from Gaggenau at the time. Daimler supplied its vehicles to Riga and Helsinki. This brought the export share of the 101 gasoline-engined fire-fighting vehicles produced between 1907 and 1914 to five percent.

After the First World War, Daimler and Benz continued their export drive with undiminished dynamism. As early as 1920, Benz delivered two 3 CS fire engines to the Netherlands. They were equipped with 6.3 liter 45 hp four-cylinder engines and reached a top speed of 40 km/h.
Two years later, a motorized DC 2c fire engine from Daimler was supplied to a place as far away as Cairo. The vehicle was powered by a 5.5 liter 40 hp engine; it had a payload of two tons and a gross vehicle weight of a little over four tons. A turntable ladder on a DC 3dF chassis arrived in a place as far away as Kobe in Japan on October 24, 1924.

Large-scale order from Königsberg

Daimler-Motoren-Gesellschaft received an unusual large-scale order in November 1921: two motorized fire engines, five motorized turntable ladders, two hose carriers and an equipment carrier were ordered by the professional fire brigade of Königsberg, whose commissioner Matthes had set himself the objective of completely reorganizing fire-fighting in the East Prussian metropolis.

All 18 vehicles had 3.5 ton chassis from Daimler. The fire-fighting bodies were made by Messrs. Kieslich in Patschkau, the centrifugal pumps by Messrs. Ehrhardt & Sehmer. Where turntable ladders were concerned, the commissioner of the Königsberg fire brigade opted for Magirus. After less than six months, all vehicles had arrived in Königsberg – the last one on May 8, 1922.

Benz vehicles for voluntary fire brigades

Large-scale orders such as the one from Königsberg for Daimler-Motoren-Gesellschaft were few and far between during the difficult post-war years. However, motorization of the fire brigades progressed irrespective of the strained economic conditions after the lost war. In particular, the voluntary fire brigades of small towns and rural communities realized the advantages of motorized vehicles.

In 1921, the Gaggenau factory launched a new chassis series that was perfectly suited to the varied requirements of the voluntary fire brigades. At the same time, Benz proved to be flexible also where the financial scope of voluntary fire brigades was concerned: from 1924 onwards, the factory manufactured a two-wheeled pump water tender that could be hitched to a crew carrier. The 25 hp four-cylinder engine of the tender delivered 600 – 800 liters of water per minute at 1500 rpm.

At the time, Benz also began producing its own centrifugal pumps. Three different pumps with capacities between 800 and 2,000 liters per minute were available. Powerful encapsulated breather pumps shortened the suction times even with large delivery heights.

Metz, one of the most important manufacturers of fire-fighting ladders and superstructures was a competent partner for Benz & Cie., producing up to 26 meter long fully automatic ladders with anti-tilt devices, extension stops and securing devices. In 1924, Metz was the first to present an all-steel ladder set made of commercially available, riveted angular profiles to the public – but this was not immediately able to prevail over the conventionally used steel-reinforced wooden ladders.

However, the Benz company got itself into financial difficulties at the time, which resulted in a cooperative agreement with its former competitor, Daimler, in 1924. Until the final merger in 1926, therefore, Daimler concentrated on heavy-duty four- and five-tonners for professional fire brigades and left the lighter chassis for voluntary fire brigades to Benz. After the merger of the two companies, all commercial vehicle activities were relocated to Gaggenau.

Technical innovations in the twenties

As hesitantly as economic activity gained momentum in the twenties, as unstoppable did technical development progress. Electrical ignition became state of the art, and as traffic volumes rose, left-hand drive and floor shift became the order of the day. Slowly but gradually, the vehicles became faster, too. The fire brigades were still driving to the scenes of fire in open-top vehicles, but vehicles without windshields – customary in pre-war times – became an increasingly rare sight.

Output ratings rising up to 100 hp – attributable first and foremost to the changeover from four to six cylinders – triggered other innovations. With both payload capacity and speed raised significantly, more powerful brakes became necessary, for example. At the time, the compressed-air brake began being widely used in heavy-duty vehicles. The diesel engine, used by Benz and Daimler for commercial vehicles as early as 1923/24, did not catch on with the fire brigades before the thirties. By contrast, there was great demand for low-frame chassis with offset frames – the sort Benz produced from 1923 first for refuse-collecting vehicles and then for buses. This design lowered the vehicles' center of gravity and improved their roadholding.

Pneumatic tires also proved to be a must at higher speeds, even though fire brigades were hesitant to use them for quite a while for fear of flat tires on the job. But fire-fighting vehicles with gross weights between five and ten tons thundering along cobble-stoned streets on solid rubber tires at 40 km/h were uncomfortable and dangerous not only for firefighters. The vibrations they caused occasionally threatened the stability of the houses along these streets.

Pneumatic tires had been on the agendas of fire brigade conventions since 1924 but it took years of positive experience gained by public transport operators to convince the majority of fire brigades of their qualities. It was true, however, that turntable ladders required support spindles to be sufficiently stable in combination with pneumatic tires.

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