The Benz Patent Motor Car Number 1 (Benz Patent-Motorwagen) is the first automobile with a combustion engine built by Carl Benz. The patent for this tricycle vehicle was filed by Benz on January 29, 1886 and granted DRP No. 37435 on November 2, 1886. On July 3, 1886, Benz conducted the first public test drive with the one-off in Mannheim. It is considered the world’s first practical motor vehicle and thus marks the birth of the modern automobile.
Benz made his crucial mobility experiences on a cranked velocipede (pedal crank bicycle) and then built a light motorized velocipede for private transport instead of a road locomotive that he initially considered for collective transport. His patent motor car is still reminiscent of bicycles and carriages.
The heart of the car was a single-cylinder four-stroke engine with a displacement of 0.954 liters. Some details can still be found on engines today: crankshafts with counterweights, electric ignition and water cooling.
“A number of tours of 250 tours per minute seemed sufficient, even a lot, and I was able to determine that this engine gave about 2/3 horsepower.”Carl Benz.
Later measurements showed 0.75 HP (551 W) at 400 / min. The engine, which at that time weighed around 110 kilograms, had a cylinder with an open crankcase, an inlet slide valve controlled by an eccentric rod, and an outlet poppet valve, actuated via cam, bumper and rocker arm. It was lubricated over drip oilers. Benz designed the large flywheel to be installed horizontally in the chassis because he feared that if the vehicle was positioned vertically, the steering and stability of the vehicle would be impaired in tight bends due to the gyro effect.
A surface carburetor developed by Benz processed the mixture and at the same time contained a petrol reserve of 4.5 liters. Although it was not petrol in the sense of petrol, but a light petrol called ligroin, which was available in pharmacies. The composition of the gasoline-air mixture could be corrected with a sleeve slide valve, which more or less covered the holes for the additional intake pipe and thus regulated the power output. In the vehicle, this slide was easily accessible below the driver’s seat.
Benz devoted several attempts to the ignition until he found a solution that was adapted to the low power of the battery current at the time. He transformed the current to a higher voltage using a spark inductor developed by Heinrich Daniel Rühmkorff. The spark plug was also developed in-house. Later examinations showed that the material of their electrodes largely corresponded to the commercially available spark plugs of the 1930s.
The cooling of the internal combustion engine was a particular problem because it could not simply be connected to a cooling water line like a stationary engine. Benz went for simple evaporative cooling (evaporative cooling ), which proved to be effective and sufficient with the low output.
In Let the engine was courageous turning the flywheel. The fact that the fuel supply in the carburetor was not long enough did not bother Benz in the patent motor car. After all, driving the vehicle over 100 kilometers required around 10 liters of Ligroin, which was still considered dangerous at the time.
Frame and Body
The frame was bent from steel tubes and welded. Since the car should have rear-wheel drive, i.e. it was pushed from behind, the problem of steering arose, which had to be constructed differently than with a towed car. The turntable steering, which is otherwise customary for carriages, was out of the question, and after his two-wheel experience, Benz decided on a lightly built three-wheeler, a three-wheeled velocipede (see patent text). The front wheel hung in an unsprung fork and was steered by a rack connected to a crank. (It wasn’t until 1893 that Benz used a steering knuckle). The three wire spoke wheels with solid rubber tiresBenz manufactured it himself, only the rims were “third-party” from the Adler bicycle factory in Frankfurt. The front wheel ran in a ball bearing, as was customary in bicycle construction at the time, the rear wheels in white metal bushings.
The car was driven with a chain to the left and right of the countershaft via the rear wheels, which in turn were connected to the frame via a rigid axle and full elliptical springs. On the countershaft there was a drive pulley with integrated differential, next to it an idle pulley. The belt transmission thus only had one forward gear and no reverse gear. The flat belt between the camshaft driven by bevel gears and the countershaft also acted as a clutch thanks to the idler pulley. The flat belt was moved from the loose to the fixed pulley to start with a belt fork. As with steam engines, the engine torque was regulated by adjusting the control of the intake valve below the driver’s seat. The reservoir for the cooling water was enthroned above the engine. The brakes were applied using a hand lever that acted on the countershaft pulley. There was no foot brake yet.
The seat was mounted directly on the frame on curved springs in front of the engine and covered with quilted leather. A low, leather-covered railing in the back and on the sides gave firm support.
The chains gave cause for concern: the bicycle chains were still defective, mostly too soft, and therefore stretched a lot, jumping out of the gears or tearing. But since there were no better ones, Benz had to be content with the existing material.
The first test drives took place in the factory courtyard in 1885 for reasons of secrecy and ended at the factory wall. The first “excursion” on the open road – at night – only took a few minutes. The car stopped after a hundred meters. However, the range was gradually improved in numerous tests.
On January 29, 1886, the vehicle was finally registered for a patent with the Reichspatentamt under number 37435. At the first public and documented exit on July 3, 1886 on the ring road in Mannheim, Benz ‘son Eugen walked alongside with a bottle of gasoline “to refill when the gasoline runs out”.
The first “Benz” drove through the city on September 16, 1888 in Munich.
The car remained a one-off, as did its direct successor, the number 2 patent motor car. It was first converted into a four-wheel car and later butchered. It was reconstructed in 1903. This Benz Patent Motor-Wagen No. 1 is today in the traffic center of the German Museum in Munich.