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How the gasoline engine conquered fire fighting: 95 years ago, Daimler-Motoren-Gesellschaft supplied the first fire-fighting vehicle with gasoline engine
At the end of the 19th and the beginning of the 20th century, towns and cities expanded rapidly due to increasing industrialization, presenting new challenges in terms of the protection against fire. Distances became rather long for the propulsion variants customary at the time, that is horses, steam engines and vehicles with electric drive systems. The demands increasingly made on the fire brigades of large cities were aptly summarized in News about Daimler Commercial Vehicles: “High-speed vehicles for preventing fire and for a first attack on the source of fire, capable of carrying a crew of eight or nine men as well as carbonic-acid extinguishers and all the required equipment.”
Reservations against gasoline
However, the fire brigades still had strong reservations against the gasoline engine. They felt that it would be extremely dangerous to approach a fire with an explosive material in the fuel tank. They also doubted that gasoline-powered engines had the required reliability. On the other hand, the disadvantages of keeping horses were all too obvious: the animals had to cared for, incurring high fodder and personnel costs. At the time, fire brigades were engaged in heated discussions about the best solution – steam, electricity or gasoline.
All three versions existed side by side until World War I – gasoline engines took a while in establishing themselves. At a convention in 1907, the professional fire brigades still recommended the use of electric motors for inner-city assignments and steam propulsion for longer distances.In spite of this, the gasoline engine gained ground rapidly, thanks to the successful start of the first gasoline-engined fire-fighting vehicle, supplied by the Berlin factory of Daimler-Motoren-Gesellschaft to the fire brigade in Frankfurt/Main, in 1907. The Frankfurt fire fighters had tested the suitability of their brand-new vehicle for traveling long distances by using this vehicle, which had capacity for a crew of nine, for carrying a delegation of five people to the above-mentioned convention which was staged in Stuttgart in 1907.
From Frankfurt to Stuttgart in seven hours
The distance of 197 kilometers was covered in seven hours by the new fire-fighting vehicle with solid rubber tires, a conventional 1.5 ton truck frame and a four-cylinder engine with an output of 28/32 hp. Under the conditions prevailing in those days, a travel time of seven hours for the journey from Frankfurt to Stuttgart was impressively short.
The Daimler D4 engine developed 28 hp at 800 rpm and 32 hp at 950 rpm. In fourth gear, the fire-fighting vehicle reached a top speed of 30 km/h and was still capable of climbing one percent inclines at that speed. In first gear, it was capable of climbing gradients as steep as 14 percent.
35 kilogram barrel used as a fuel tank
As in all Daimler vehicles, the fuel tank was fitted underneath the frame at the rear. For safety’s sake, however, the Frankfurt fire brigade, still a bit wary, had specified a barrel with a capacity of merely 35 kilograms instead of the usual 150 kilogram vessel.
This tank volume may have been modest but it gave the vehicle a range of as much as 90 kilometers. The following calculation was drawn up in the News about Daimler Commercial Vehicles: “Since the longest distance to be covered in Frankfurt/Main is two times 7.5 kilometers, the vehicle can set out and return six times on one tank filling.” To dispel any doubts, the article continued: “And this has already happened.”
Carbonic acid, double-sided axes and magnesium torchesThe Frankfurt fire brigade established that the “ shortest time for getting the vehicle ready for setting off after the first alarm” was 18 seconds. The vehicle, weighing just under five tons with a complete crew, usually set off equipped with exactly 84 items, ranging from a nine-meter-long two-part sliding ladder via carbon-acid bottles, double-sided axes and safety blanket to magnesium torches and chimney-sweeping equipment.
It soon earned great praise, especially for its speed, as horse-drawn fire-fighting vehicles had no chance of keeping up with the gasoline-engined vehicle. Time and again, the Frankfurt fire fighters were able to report that “the motorized vehicle arrived at the scene of fire up to five minutes earlier than the fire tenders.”
Take your foot off the accelerator before cornering!
The drivers were categorically denied any sort of sporting ambition. Those at the wheel had received “the strictest” instructions from their superiors “to give the vehicle a slower speed” some 50 meters before a bend and not to pick up speed again before a straight stretch of road was reached. The result: “ There has been no incident of vehicle skidding.”
The first gasoline-powered fire engine from Daimler in Berlin also proved to be highly reliable. Fire chief Schänker noted, among other things: “Ever since the vehicle has been put into operation, it has been tested every morning immediately after roll call. It always worked well both on these occasions and on 25 journeys to fires.” Minor complaints, according to Schänker, had always been attributable to improper handling.
The trick with the power take-off
Before long, a new field of activity opened up for the gasoline engine. The News about Daimler Commercial Vehicles informed its readers: “We are able to use the upper transmission shaft for directly driving a pump, a ladder or any other mechanism, by installing a switch-over clutch.” The Frankfurt fire brigade did not hesitate and ordered a second “self-propelled fire-fighting vehicle with gasoline engine” within one year; the new one featured a centrifugal pump powered in the above-described way instead of the conventional steam equipment.
Compared to the steam-powered version, this pump had the advantage that it was instantly operational, whereas the steam pump always required a certain set-up time. As early as 1909, a chief engineer and journalist from Stuttgart, a man called Bischoff, concluded that “In the case of far-away fires, there is nothing to beat the combination of Daimler frame and gasoline engine with Schiele turbine pump in terms of efficiency and performance.”