Vehicles of the early 20th century: automobiles: largest sales volume, overall performance stable. Electric vehicle: A battery-operated electric tram. Trams first appeared in Germany in 1882. In 1923, Britain built its first trolleybus. Internal Combustion Engine: Gradual Improvements. In 1901, Maybach invented the honeycomb cooling water tank. In 1917, Cadillac developed the electric starter. In 1929, Cadillac developed the synchronizer. In 1914, the drum brake was born. In 1921, the American Duesenberg Company developed a hydraulic booster. Development of automobile tires: solid spoked iron tires with solid rubber tires (invented by the French Michelan brothers) detachable wheel wire tires. Development of highways: gravel and dirt asphalt roads. In 1910, the British Highways Agency was established to build asphalt roads. Cement roads began to appear in 1914. In 1924, Italy first built a highway. In 1942, Germany built a modern standard highway. A new era of mass production of automobiles: In 1901, American Odell produced and sold 425 Oldsmobile automobiles, reaching 6,500 in 1905. The birth of the automobile production line: In 1913, Ford first invented the scientifically designed automobile assembly line, which greatly improved the production efficiency of automobiles and was quickly followed by other automobile manufacturers. Model T: From 1908 to 1927, Japan produced 15 million units, setting a world record at the time. Mass production and sales promote the development of new automotive technologies: front wheel brakes; ignition switches with keys; automatic starters, etc. Development of the car body: Starting from people's pursuit of shape, color, and riding comfort, the integrity and rigidity of the car body are enhanced. The development process is as follows: Horseless carriage: body and compartment; Ford Type A: setting a gear in front of the seat Wind board; box car: the whole is square, in the form of a box; streamlined car: as the speed of the car increases, aerodynamics is applied to the design of the car body; ship type: mechanical engineering and fluid mechanics are considered. In 1885, the two-stroke gasoline engine invented by German Benz was installed on a three-wheeled vehicle. This was the prototype of modern automobiles. Features: Spark ignition, water cooling, rear drive, front wheel steering. Now in the Munich Science Museum. A four-wheeled vehicle developed by the German Daimler Company in 1886. We now think of 1886 as the year the automobile was born. The car is recognized worldwide as the world's first four-wheel vehicle powered by a gasoline engine. Overview of the history of automobile development before the 1950s: In 1886, Karl Benz applied for a patent for his automobile. In 1889, Frenchman Peugeot invented the transmission and differential. In 1892, American Delia invented the carburetor. In 1894, Michelin invented the removable pneumatic tire. In 1902, the patent for the disc brake was obtained by the British, and the patent for the drum brake was obtained by the French Renault. In 1908, the Ford assembly line was established. In 1911, car lights were introduced. In 1952, seat belts were introduced to the United States. In 1954, the fuel-injection engine was introduced.