Unimog 401

After World War II, German engineer Albert Friedrich built the first Universalmotorgerät, however, Daimler-Benz declined to put it into series production. Manufacturer Boehringer in Göppingen on the other hand was interested and produced a prototype for the 1948 DLG-exhibition in Frankfurt. The Unimog attracted much interest, encouraging Boehringer to begin series production. Until 1950, approximately 600 Unimog 70.200 were made; their brand logo was an ox-head with U-shaped horns. In late 1950, Daimler-Benz purchased Boehringer moving Unimog production to Gaggenau, beginning series production in May 1951.^[4] Initially, the Unimog's type number was 2010, changing to 401 in 1953, with the 401 becoming a new type. The Unimog 401 was the first Unimog to receive the Mercedes star on its grille.^[5]

 

The Unimog 401 is a very compact vehicle with an approximate length of just 3.5 metres (11 ft 5+3⁄4 in). It has a U-shaped ladder frame, beam portal axles both in the rear and front, with four same-sized wheels. Each axle has additional reduction gears built in. Both front and rear axles are supported by a central joint and panhard rods. The 401 has coil springs and hydraulic shock absorbers. Daimler-Benz used 6.5–20" multi-purpose tyres, that are designed for both on and off-road applications. The brake system is hydraulic, the 401 having drum brakes for each wheel.^[6] The 401 has a wheelbase of 1,720 mm (67+3⁄4 in); the 402, 2,120 mm (83+1⁄2 in).^[2]

 

The 401 uses a car engine, type OM 636 VI. It is a water-cooled naturally aspirated straight-four-diesel with precombustion chamber injection, OHV-valvetrain and a displacement of 1,767 cm³ (1.767 L; 107.8 cu in). Its standard power output is 40 PS (39 hp; 29 kW), reduced to 25 PS (25 hp; 18 kW) at 2350 rpm for the Unimog. The OM 636 is mounted slightly inclined towards the rear, in the front of the Unimog. It has an electric starter.^[6]

The Unimog 401 uses a Daimler-Benz six-speed constant-mesh gearbox with two additional reverse gears. It has clutch-independent switchable all-wheel drive and differential locks for the front and rear axles. The clutch is a Fichtel & Sachs single-disc-dry-clutch.^[6] Daimler-Benz offered an additional two-speed crawler-gearbox as a factory option.^[7]

The 401 uses a 150 W Bosch alternator, a 12 V / 105 Ah lead-acid battery, two headlights, two rear lamps, electric trafficators, windscreen wipers and a horn. A plug socket for a trailer was offered as a factory option.^[6]

A flatbed is mounted on the rear, measuring 1,500 mm × 1,500 mm (59+1⁄16 in × 59+1⁄16 in), designed for a payload of 1,000 kg (2,200 lb). The 401 has a spring-mounted hitch in the rear and a standard hitch in the front. For additional equipment, it has an anchor rail.^[6]

For power take-off, the Unimog was available with front and rear PTOs (DIN 9611, 540 rpm). The rated power is approximately 22 PS (22 hp; 16 kW). A 315 mm (12+3⁄8 in) belt pulley was also available, with an output power of 22 PS (22 hp; 16 kW). Daimler-Benz also offered a spare wheel, rear twin tyres, a trailer-brake-system, a winch, a mowing bar and air compressors for the 401.^[7]

The previous Unimog 2010 was offered as a cabrio with a foldable top, a concealing windscreen, removable side windows and a rigid rear panel. It was available in the colour Unimog-grün. After developing the 2010 into the 401, the closed cab was offered. The cabrio version then became Version A while the cab-version became Version A/F. Unimogs with a trailer-brake-system were called Version B and Version B/F. Unimogs with a closed cab were available in the paint colours Unimog-grün, hellgrau and Mercedes-blau.^[7]

• Werner Oswald: Mercedes-Benz Lastwagen und Omnibusse 1886–1986. Motorbuch Verlag Stuttgart, 2008, ISBN 978-3-613-02943-9.