Benz Patent-Motorwagen 1886 — the four-stroke in section (3D)
About this app
The first automobile as a 3D model: vehicle, cut-open engine and exploded view. The four strokes run with a p-V diagram, a flywheel slider shows why the engine stalls without mass, the belt switches between idle and drive, a map follows Bertha Benz's 1888 drive.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
The first practical automobile
Carl Benz filed his motor car for a patent on 29 January 1886 (DRP 37435). The tricycle has a steel-tube frame, wire-spoked wheels with solid rubber and a steering crank. Behind the seat works a horizontal single-cylinder four-stroke engine of 954 cc delivering 0.75 hp at 400 revolutions per minute. It is cooled by evaporation, the mixture comes from a surface carburettor and ignition is by induction coil and spark plug. A flat belt, a differential and two chains drive the rear wheels; the car goes no faster than 16 km/h. Vehicle number 1 is on display in the Deutsches Museum in Munich.
What the app shows
An own 3D reconstruction in three views: the whole vehicle, the engine cut open horizontally and an exploded view of the assemblies. In the section, piston, connecting rod and the vertical crankshaft with the horizontal flywheel move; the charge in the cylinder takes the colour of the stroke, and a p-V diagram shows pressure and volume alongside. A flywheel panel calculates the engine speed over two revolutions. Wood, leather, brass and steel appear in natural tones; anything schematic is labelled as such.
Things to try
Step through the four strokes and watch the inlet slide, the spark and the exhaust valve, or let the engine run in slow motion. Make the flywheel lighter: the speed fluctuates more and more until the engine stalls in the compression stroke. Move the belt from the idler pulley to the fixed pulley and the car rolls off along a country road. Colour the power path from piston to wheels, tap parts for an explanation or follow Bertha Benz's long-distance drive from Mannheim to Pforzheim on the map.
Frequently asked questions
- How does the engine of the Benz Patent-Motorwagen work?
- It is a horizontal single-cylinder four-stroke engine: intake, compression, power and exhaust in two revolutions. A flat slide admits the mixture from the surface carburettor, a spark from the induction coil ignites it and a poppet valve lets the exhaust out. It delivers 0.75 hp at 400 revolutions per minute.
- Why did the Benz Patent-Motorwagen have such a large flywheel?
- Only one stroke in four delivers work. The flywheel stores that energy and carries the piston through exhaust, intake and above all compression. If it is too light, the speed fluctuates strongly or the engine stops before ignition. It lies horizontally; the usual explanation is that an upright wheel would have acted as a gyroscope on the steering.
- Did the first car have a clutch and a gearbox?
- Not in today's sense. A flat belt ran either on a loose idler pulley, so the car stood still with the engine running, or on the fixed pulley, so it drove. There was one gear and no reverse, and the speed depended on the engine speed alone.
- What can I try in this app?
- You switch between vehicle, engine section and exploded view, select the four strokes one by one or run them in slow motion, reduce the flywheel mass until the engine stalls, shift the belt and follow the 1888 drive on a map. The AI tutor can also demonstrate the app.
Subject: Physics experiments (Deutsches Museum)
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