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CLASSIC FORESTRY UNIMOG
The legendary Mercedes-Benz Universal-Motor-Gerät, or Unimog, is an almost unique concept – a capable off-road vehicle and an innovative platform for agricultural, transport, military, forestry and municipal applications. As a base unit or fitted with special attachments, it has been able to travel on road or rail, drive through water, pull trailers, fight fires, drill holes, dig trenches, plough fields, build roads, dump waste, sprinkle water, lift loads, blow snow, mow grass, carry people and haul timber. Offering unrivalled versatility, the Unimog has excelled in the toughest conditions and has proven itself on a global scale. It has become a legend the world over and, for many tasks, there is no viable alternative.
Until 2002, the Unimog was manufactured at Daimler-Benz’s Gaggenau plant in the German state of BadenWürttemberg. Both the company and the factory were of great historical significance. The names of Daimler and Benz were synonymous with some of the earliest experiments with internal-combustion engines, while Gaggenau was the home of one of Germany’s first farm tractors.
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German pioneers, Gottlieb Daimler and Karl Benz, were both separately experimenting with petrol-powered horseless carriages as early as 1886. The Mercedes-Benz brand was created after their two firms, Daimler-MotorenGesellschaft and Benz & Cie, were merged on June 28th 1926 to form Daimler-Benz; the German Daimler business having adopted the Mercedes trademark in 1902 to avoid confusion with the British Daimler company in Coventry. Prior to the merger, both the Daimler and Benz concerns had manufactured farm tractors and motor ploughs including some of the world’s first diesel-powered machines. Production continued after the merger with the Benz-Sendling and Mercedes-Benz Type OE designs until Daimler-Benz suspended tractor manufacture in 1933.
The Gaggenau factory, originally an ironworks, was acquired by Benz as its main production centre for commercial vehicles in 1907. In 1919, it began manufacturing the ‘Benz-Gaggenau LandwirtschaftsTraktor’ – a mighty machine with an eight-litre petrol engine. A diesel version was also introduced in 1924, but production of both variants ended the following year. Gaggenau then concentrated on commercial vehicle production and expanded considerably in the years leading up to World War Two. Its export sales alone included an order for 3,000 motor lorries from China.
The outbreak of war saw Gaggenau switched to military vehicle production,
Left: 411 unit harvesting with a trailed Claas Super Junior combine.
Below: Ploughing with the Unimog, the high driving position a boon.
making Maultier (Mule) half-track rough terrain vehicles. It also experimented with wood-gas producer systems until Allied air attacks during 1944 destroyed much of the buildings and brought production to a standstill. A rebuilding programme began after the capitulation. Gaggenau was in the French occupation zone and was requisitioned to manufacture Jeep, Dodge and GMC engines, and axles for the French Army. Currency reforms and the political reorganisation of West Germany allowed further rebuilding, which saw the plant return to making medium and light trucks.
DESIGNING THE ULTIMATE WORKHORSE
Many of the policies for post-war Germany were influenced by the Morgenthau Plan, devised by Henry Morgenthau Jr, the United States Secretary of the Treasury. Morgenthau’s proposals to turn Germany from an industrialised nation into an agrarian economy were never really
implemented, but the plan inspired Albert Friedrich, the former manager of DaimlerBenz’s aero-engine division, to develop an all-purpose agricultural vehicle. Friedrich’s vision was to design a machine that could be used both as an agricultural tractor and a transport vehicle. His concept, outlined in May 1945, called for good cross-country performance with enough ground clearance to cope with rough terrain. He also wanted the vehicle to have good weight distribution, a platform for mounting implements or carrying loads, and a comfortable working environment for the driver and a passenger.
Having submitted his plans to the controlling authorities in September 1945, Friedrich managed to obtain a production order the following month. The financial backing came from an unusual source: Erhard & Söhne, jewellery manufacturers who specialised in fine metalwork. The development work began in January 1946 at Erhard & Söhne’s factory in Schwäbisch Gmünd and Friedrich was joined in the project by the engineers, Heinrich Rossler and Hans Zabel.
Rossler finalised the design of the vehicle the following March. The four-wheel drive layout had a differential lock in each rigid portal axle; the track width was set at 1,270mm, exactly the width of two potato rows. Coil springing, shock absorbers,
SPECIFICATIONS Unimog U34/411 (1970)
Engine: Mercedes-Benz OM636 4-cylinder diesel, 1,767cc, 38hp@2,750rpm Transmission: 6 forward and 2 reverse speeds; range 3.5-53km/h Clutch: Single-disc dry clutch Dimensions: Length 3.4m; Wheelbase 2.1m; Width 1.6m; Height 2.1m; Ground clearance 0.4m; Payload 1,000kg; Weight 2,200kg
upholstered seats and a cabin with a folding canvas hood made the driver’s lot a more pleasant one, while provision was made for front and rear power take-off and rear linkage.
The prototype vehicle, which was fitted with a petrol engine, ran for the first time on October 9th. The concept proved itself during extensive trials; Hans Zabel suggested naming the vehicle after an acronym of Universal-Motor-Gerät (universal motor machine) and the Unimog was born. The planned production was undertaken by Gebrüder Boehringer, machine-tool manufacturers from Göppingen. With Erhard & Söhne supplying several components, enough materials were procured for an initial run of 100 vehicles. The petrol engine was also changed to a diesel supplied by DaimlerBenz, the 1.7-litre OM636 unit developing 25hp, before the Unimog was launched at the DLG Show in Frankfurt in 1948.
DAIMLER TAKES OVER PRODUCTION
The Unimog did exactly what it said on the tin and was a true all-purpose vehicle. It could plough, cultivate, mow and operate most trailed, mounted or power-driven farm implements; it could transport loads, carry equipment or haul trailers on the road at speeds of up to 50kph (31mph). The payload on the loading platform was 1 tonne. Full production began with the 70200 series in the spring of 1949. Some 600 Unimogs had been built by Boehringer by
Fitted with a rear-mounted winch, the do-it-all Unimog made an excellent timber tractor.
A Unimog fitted with a Howard Rotavator suitable for forestry cultivation and planting operations.
the end of 1950, but the Göppingen plant had resumed machine-tool manufacture and hadn’t enough capacity to meet the growing demand. Consequently, negotiations began for Daimler-Benz to take over the manufacture of the vehicle with the production centred at Gaggenau.
The first Unimog built at Gaggenau was delivered on June 3rd 1951. This 2010 series vehicle, which was virtually identical to the Boehringer version and still had the 25hp diesel engine, was awarded a DLG silver medal. A fully enclosed steel cab was introduced in March 1953 and the improved 401 series followed in August.
The remainder of the decade saw further changes with petrol, long-wheelbase and fully synchronised gearbox options introduced. The power of the diesel engine was upped to 30hp on the 411 model in 1956 and the synchronised transmission, offering six forward and two reverse speeds, was fitted as standard from 1959.
The 50,000th Unimog rolled out of Gaggenau in May 1961. Its scope now extended beyond just agriculture to also include military, forestry and municipal applications, which saw another 100,000 vehicles find customers over the next 10 years. For farmers, it was the original ‘systems’ tractor, capable of mounting
SPECIFICATIONS Mercedes MB-trac 65
Engine: Daimler-Benz OM314 4-cylinder diesel, 3,782cc, 65hp@2,400rpm Transmission: 16 speeds, forward or reverse; speeds from 0.13kph to 25kph Clutch: Two single-plate dry clutches, 280mm Fuel tank: 120 litres Dimensions: Length 4.2m; Wheelbase 2.4m; Width 2.04m; Height 2.65m; Ground clearance 0.5m; Wheel track 1.7m; Weight 3,000kg
The Unimog could be fitted with air-braking for handling heavy loads of timber at high speed.
Mercedes-Benz Timeline
1863 Gottileb Daimler begins designing farm equipment 1879 Karl Benz patents a two-stroke engine 1886 Daimler and Benz experiment with petrol automobiles 1915 Daimler Motorpflug (motor plough) goes into production 1918 Benz builds Sendling motor plough 1919 Launch of Benz-Gaggenau
Landwirtschafts-Traktor 1920 Daimler Pflugschlepper (plough tractor) introduced 1923 Benz-Sendling Type BK diesel tractor launched 1926 Mercedes-Benz brand created from merger of Daimler and Benz 1928 Type OE first tractor produced under Mercedes-Benz name 1930 British-built McLaren-Benz appears at World Tractor Trials 1933 Mercedes ends tractor production 1944 Allied air attacks curtail military vehicle production at Gaggenau 1948 Unimog launched at DLG Show in Frankfurt 1951 Daimler-Benz takes over manufacture of Unimog 1961 50,000th Unimog rolls out of
Gaggenau 1971 Mercedes MB-trac launched at
DLG Show 1975 MB-trac 700 and 800 models arrive on the market 1976 Six-cylinder MB-trac 1100 and 1300 added to range 1984 Reverse-drive MB-trac awarded
RASE medal 1991 Mercedes-Benz ends MB-trac production 2002 Unimog production moves to
Wörth factory 2007 New Unimog features including
ISOBUS systems
sprayers, fertiliser spreaders, even forage harvesters. The versatile Unimog became synonymous with off-road capability almost worldwide as the range expanded to include six-cylinder models of up to 100hp.
THE NAME LIVES ON
A rationalisation of Daimler-Benz’s manufacturing operations in 1967 saw Gaggenau’s heavy truck production transferred to Wörth on the Rhine, leaving the Baden-Württemberg plant free to concentrate on axles, transmissions and the Unimog vehicles. With sales across the world, the 150,000th Unimog was produced in 1971. That year’s DLG Show also saw the launch of the MB-trac as the Mercedes-Benz three-pointed star adorned yet another new product from Gaggenau.
A new range of U-Series Unimogs was launched in 1966, five years before the MB-trac models appeared.
Left: Unimog platform’s versatility offered a quick and economical solution to ditch cleaning.
A spin-off from the Mercedes Unimog, the MB-trac was one of the first ‘systems’ tractors with front and rear power take-off, rear three-point linkage and the option of front linkage. The three implement mounting areas (front, centre and rear) allowed a combination of equipment for a variety of agricultural tasks. The load space behind the cab was ideal for mounting sprayers, fertiliser spreaders or seeders.
A later agreement saw the MB-trac range marketed alongside the Deutz Intrac as part of a joint venture under the TracTechnik name. Production continued until 1991 when Daimler-Benz pulled out of the tractor market following the launch of the JCB Fastrac, which was a largely similar concept. Just over 40,000 MB-tracs had been sold during its 20-year production run. The rights to the MB-trac design were sold to Werner GmbH at Trier on the Moselle. Werner continued to manufacture the tractor as the WF-trac, mainly for forestry or industrial applications. The company’s current timber forwarders and skidders still use Mercedes power-units.
Meanwhile, in 2001, Gaggenau celebrated 50 years of Unimog production having built more than 300,000 vehicles. The following year, Unimog production was relocated to the Wörth factory, and Gaggenau became Daimler-Benz’s main transmissions centre. Although the MB-trac is no longer part of the Mercedes range, today’s Unimog models remain strong contenders in the agricultural market with machines for farming, forestry and contracting applications.
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