Mercedes-Benz W 125

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Hermann Lang 1977 in a Mercedes-Benz W 125

The Mercedes-Benz W 125 was the Grand Prix racing car produced by Daimler-Benz AG in 1937 . Since the rules limited the displacement and thus also the achievable output from 1938, the W 125 with more than 600 hp was considered to be the most powerful and impressive car that had competed in Grand Prix races until the beginning of the 1980s.

history

The W 125 was the successor to the Mercedes-Benz W 25 , the first " Silver Arrow " that Mercedes had developed for the so-called 750 kg formula and used from 1934. The weight formula on which both models are based (750 kg = maximum weight of the car without driver, fuel, oil, water and tires) was originally intended to be valid until 1936, but was extended until 1937.

The main designers of the W 125 were Max Wagner and Rudolf Uhlenhaut . Uhlenhaut undertook test drives himself, but he was not allowed to participate in races. Knowing some of the shortcomings of the previous model (extreme changes in camber and toe during compression), they designed a chassis with a De-Dion rear axle instead of a swing or swing axle . The front wheels were suspended from lower and upper wishbones of different lengths . The frame of the car consisted of oval tubes (1.5 mm thick sheet steel) with four cross members made of round tube.

The W 125 was initially powered by an eight - cylinder M 25 in- line engine. The M 25 E version from 1936 with 4.74 liters and 473 hp can be viewed as a separate exhibit in the Mercedes-Benz world . In the course of 1937 the displacement was increased to 5.66 liters, the output of this variant is given as up to 646 hp. In racing, however, tire wear set limits to performance, the Auto Union Type C had around 500 hp.

At the Avus race in 1937 , Mercedes used the “normal” W 125 and those with streamlined fairing, a fully faired special racing car with a 5.57 liter V12 engine that developed up to 598 hp and allowed a top speed of over 370 km / h . The driver of this car was Manfred von Brauchitsch .

Due to the rule changes for the 1938 Grand Prix season , which limited the displacement of supercharged engines to 3 liters, which was succeeded by Mercedes-Benz W 154 with twelve-cylinder - V engine developed.

Cockpit of the W 125

Data

W 125 Technical specifications
Engine: 8-cylinder in-line engine, type M 125 F
Bore × stroke: 94 × 102 mm
Displacement : 5660 cc
Performance (mean): 570 hp (419 kW) at 5800 rpm
Crankshaft : one-piece with counterweights, supported nine times
Motor control: two overhead camshafts , driven by spur gears
Valves: 2 inlet, 2 outlet per cylinder
Charge: 1 vertically arranged Roots blower
Lubrication: Dry sump
Cooling: water
Transmission: 4-speed
Chassis : Tubular frame
Front suspension: Double wishbones with coil springs
Rear suspension: De-Dion axis with longitudinal rotating bars
Shock absorber : hydraulic lever dampers
Brakes: hydraulically operated drum brakes
(drum diameter 400 mm)
Wheelbase : 2800 mm
Track : 1475/1400 mm
Dry weight : 744-749 kg
Top speed:  approx. 320 km / h (depending on gear ratio and body)

The W 125 achieved six first, nine second and six third places in the 1937 Grand Prix. The drivers were Rudolf Caracciola , Manfred von Brauchitsch , Hermann Lang , Christian Kautz , Richard Seaman and Goffredo Zehender .

W-125 record car followed by a Mercedes-Benz C 111 Type III in the café of the Mercedes-Benz Museum

Record car W 125

On the basis of the Grand Prix car W 125, Mercedes built a world record car with a V12 engine (5577 cm³) in 1937 . Although this V12 engine had less displacement than the 8-cylinder in-line engine M 25, it was flatter and more aerodynamically favorable. Rudolf Caracciola already reached a top speed of 395 km / h with this car in the autumn of 1937, which almost became his undoing when the front end rose at this speed. The body was then redesigned. Among other things, by switching the engine cooling to ice, a conventional cooler was no longer required , so that the air inlet opening at the bow was reduced and the c w value was reduced to 0.157. Additional carburettors increased the engine output of the DAB V12 supercharged engine from 570 hp (419 kW) to 736 hp (541 kW) at 5800 rpm.

With the optimized car, but with the same engine and chassis as in 1937, Caracciola achieved a displacement of between 5000 and 8000 cm³ on January 28, 1938 on the Reichsautobahn Frankfurt – Darmstadt - part of today's A5 - over a distance of 1 km with a flying start 432.7 km / h as an average of the return trip. This was the fastest speed traveled on a public road for 79 years. On November 4, 2017, it was surpassed in Nevada by a Koenigsegg Agera RS with 444.7 km / h.

literature

Web links

Commons : Mercedes-Benz W 125  - Collection of pictures, videos and audio files

Individual evidence

  1. ^ Paul Clifton: The fastest men at the wheel. The history of the world speed records in the automobile , ( The fastest men on earth, New York 1964, German), trans. by Günther Görtz, Motorbuch Verlag, Stuttgart 1968, p. 191.
  2. Koenigsegg, Top Speed ​​- World Record. Website Koenigsegg. Retrieved November 9, 2017.