The Mercedes-Benz plant in Mannheim
The roots of the Mannheim plant, which supplies the engines for the current Mercedes-Benz trucks and buses, go far back into history. It was in 1908 that production began in the newly constructed plant owned by the joint stock company Benz & Cie., "Rheinische Gasmotoren-Fabrik in Mannheim". The complex on the Luzenberg site in Mannheim-Waldhof was inaugurated on 12 October 1908. At that time the site area covered with production buildings was around 35 000 m2.
The most important post-war innovations at Benz & Cie. included the work on vehicle diesel engines. The keystones for this new technology were created by the diesel pioneer Prosper L’Orange, who was head of engine testing at Benz from 1908. In 1909 he discovered the pre-chamber principle, followed by the needle injection nozzle in 1919 and the controlled injection pump in 1921. The first land vehicle to be equipped with a diesel engine accordingly came from Mannheim: in 1922 Benz & Cie. presented a three-wheeled agricultural tractor developed together with Sendling, a Munich-based manufacturer of agricultural machinery.
Mannheim, the birthplace of the diesel truck
On 14 April 1923, after successful introduction of the diesel pre-chamber system, Benz & Cie. decided to commence series production of a four-cylinder diesel engine. The model OM 2 initially developed 45 hp (33 kW) at 1000 rpm. As the world's first diesel trucks, these test vehicles were also used for on-site transport duties in Mannheim. In 1924 the truck entered series production with an engine output increased to 50 hp (37 kW).
In May 1924, Daimler Motoren Gesellschaft (DMG) and Benz & Cie. concluded a contract confirming a pooling of interests. Both manufacturers were resolved to exploit synergies in the difficult German car market, rather than competing against each other in identical market segments. On 28/29 June 1926, the merger between DMG and Benz & Cie. was completed. Benz & Cie. contributed two locations to the marriage: the joint stock company Benz & Cie., Rheinische Automobil- und Motorenfabrik, Mannheim, and Benzwerke Gaggenau. DMG brought the plants in Untertürkheim, Marienfelde and Sindelfingen into the new company.
From the Blitz to the Benz
After the 2nd World War, Mannheim was the first Daimler-Benz AG location to resume production. A licenced version of the Opel Blitz was produced in parallel with reconstruction of the plant. There was great demand for the initial daily output of 20 trucks: commercial vehicles were urgently required, as the railways and marine transport were unable to supply the cities with food and other necessary consumer goods.
In summer 1949, however, the new Mercedes-Benz L 3250 truck celebrated its debut. This was one of the most important foundations for the development of the modern Mercedes-Benz truck portfolio: the L 3250 is seen as the trailblazer for the rise of Mercedes-Benz to become the European market leader for trucks in the medium weight class.
In March 1951 Mercedes-Benz concentrated its entire bus production in Mannheim. Nonetheless the plant continued to manufacture medium-duty trucks there, for example the L 4500 which had its debut at the International Motor Show (IAA) in Frankfurt in March 1953. This 4.5-tonner joined the well-proven 3.5-tonner, the L 3500, in the Mannheim product range.
Mannheim is the birthplace of Mercedes-Benz commercial vehicle engines
One major building block in this flagship plant was the foundry, which Mercedes-Benz opened in Mannheim in 1965 and which is still one of the world's leading producers of cast iron vehicle components. Construction began in 1962, and when opened the foundry was regarded as the most modern of its type anywhere in Europe. As part of the restructuring programme for commercial vehicles, the plant concentrated on grey cast iron engine components, the production of commercial vehicle engines and bus production.
In the new production structure for the Mercedes-Benz commercial vehicle sector, Mannheim took on the role of central engine producer. From 1972 the engines built here also included the new generation of commercial vehicle diesel engines, the OM 400 series. Among them the legendary OM 403, the ten-cylinder unit for the 1632. A popular collector's item in the classic scene, and still in day-to-day operation in many places. As early as 1975, the one millionth commercial vehicle diesel engine left the Mannheim assembly line. In 2016 the plant celebrated a production milestone, the one millionth engine in the OM 500 series.
The new OM 47x and 93x families dominate production
In the highly emission-controlled environment of today, engines of the Heavy Duty Engine Platform and the Medium Duty Engine Platform dominate the production lines in Mannheim. These platform designations were initially internal, but they are now generally known development projects. The engines are intended for worldwide use, which is why there are overseas variants at Detroit Diesel.
The mainstay for Europe is the completely newly developed heavy-duty OM 47x engine series. The x was first replaced by a 1 for the New Actros: the OM 471 was first introduced with 310 kW (421 hp) to 375 kW (510 hp), and 2100 to 2500 Nm of torque. As in the entire HDEP/MDEG family, the exhaust emissions are treated in accordance with the Euro VI standard. High torque even at less than 1000 rpm, and almost peak output at 1400 rpm, lead to excellent driveability.
Evolution and more family members
The first evolutionary stage of the new bestseller has meanwhile entered the fray as well. A further reduction in operational engine speeds is also the result of the turbochargers developed and produced in-house in Mannheim. The exhaust gas recirculation system has also been redesigned, with a considerable improvement in efficiency. The new top-of-the-range model is the 390 kW version (530 hp, 2600 Nm) in the Actros 1853, which is displayed at Retro Classics 2017.
While the large-displacement OM 473 with up to 460 kW (626 hp, 3000 Nm) caters for the upper power segment, the new OM 936 in-line six-cylinder is a representative of the four and six-cylinder OM 93x generation with a working displacement of 1.3 l per cylinder. This new design features numerous technical highlights, for example a max. injection pressure of 2400 bar in the common-rail system, or the world's first adjustable exhaust camshaft in a diesel engine. Output ranges up to 220 kW (299 hp).
Whether the OM 936, OM 470, OM 471 or the new OM 473 – all the engines already meet the Euro VI emission standard. They feature Blue-Efficiency Power with common-rail injection, a closed loop particulate filter system and exhaust gas recirculation. The exhaust gases are treated using BlueTec 6 technology with SCR and AdBlue injection, with a downstream oxidation catalytic converter and particulate filter.
Remanufactured engines from Mannheim
Alongside engine production, the remanufacture of engines for commercial vehicles and cars is a fixed part of the production programme at the Mercedes-Benz plant in Mannheim. This is because in the case of commercial vehicles with their long operating life, it is quite normal not to replace the engine with a new one when required, but with a completely overhauled unit in as-new condition.
The time advantage is also of great importance here: replacing the engine is often faster than repairing a defective one. The remanufactured engines are at the same technical level as new series production engines, therefore reflect the latest stage of development, and are always only fitted with genuine Mercedes-Benz parts.
Accordingly, remanufactured engines achieve the same mileage as new ones, and are covered by the same warranty. In 2006 the company already celebrated completion of the 500 000th remanufactured engine in Mannheim.