Mercedes-Benz OM 401 / OM 402 / OM 403 / OM 404
The engine series OM 401 , OM 402 , OM 403 and OM 404 is a series of diesel engines with 6 to 12 cylinders in a V arrangement . It was developed jointly by Daimler-Benz and MAN in the 1970s and built jointly for more than 20 years, while maintaining company specifics such as different combustion processes. The main area of application was the drive for trucks .
Concept and idea
The entire series is as follows:
- OM 401 V6
- OM 402 V8
- OM 403 V10
- OM 404 V12
- OM 404A V12 turbo-charged
The development of these engines was initiated by the change in the minimum engine for trucks of 8 HP / t. At 38 t for the trailer semitrailer, this resulted in 304 hp, which was no longer achievable with the old engines. For trucks, the 6/8/10 cylinders were normally used as the naturally aspirated engine, with a cylinder output of 32 hp this resulted in 192/256/320 hp. The 32t train, which was also widespread at the time, could thus be offered with the 8-cylinder engine more cheaply than the 38t train.
The aim was to jointly use expensive basic elements (such as engine blocks, crankshafts and flywheels) through the cooperation between the two manufacturers. The engines were practically identical up to below the cylinder head gasket, pistons and (single) cylinder heads were manufacturer-specific at Mercedes with direct injection (or at MAN with center ball process ). What the engines of both manufacturers have in common is the in-line injection pump in the V-cylinder.
Thanks to the modular principle used , the number of items for important components was increased further and the unit costs were reduced. The basic construction of the motors is always the same: In a V-angle of 90 degrees which was of type number type number to the crankshaft respectively to a crank extended and two cylinder added to the lengthening V. This allowed the engines to be machined on a single production line . The crankshaft always had only one crank pin for two opposing cylinders. It was therefore accepted that only the V8 engine had an even ignition interval. The V6 engine, on the other hand, ran quite unevenly, but was very light. The cylinder bore was uniformly 125 mm and the piston stroke in the smaller engines was 130 mm, the 12-cylinder had 142 mm piston stroke. The 12-cylinder engine was the only one that was also offered in the catalog with a turbocharger.
The 12-cylinder engine was not used in regular Mercedes or MAN trucks, but only in special vehicles (e.g. heavy-duty tractors). Due to its length, it was the only one that did not fit completely under the driver's cab, but stuck out at the rear. With changed peripheral equipment, all engines were also offered as built-in engines , ship drives , locomotive drives , for small power plants and similar purposes.
This series also includes the 6-cylinder in-line engine OM 407 / 407h . The engine was further developed to the OM 420 (later OM440 and OM500) and is still in production today, after more than 40 years. However, MAN has given up its stake in the joint engine plant and sold it to Mercedes-Benz.
Exemplary drive data
- DB OM 401
- 6 cylinders, displacement 9570 cm³
- Output: 141 kW (192 hp) at 2500 rpm
- DB OM 402
- 8 cylinders, displacement 12760 cm³
- Compression 17.2: 1
- Output: 188 kW (256 hp) at 2500 rpm
- Max. Torque: 834 Nm at 1400 rpm
- DB OM 403
- 10 cylinders, displacement 15950 cm³
- Output 235 kW (320 hp) at 2500 rpm
(Bore / stroke 125 × 130 mm each)
Modular advantages
In addition to the engines that could be installed in the same way, the clutches and transmissions of several vehicle series were subsequently structurally similar. This allowed customers to vary with a large number of transmission series from different manufacturers.
In accordance with the very diverse uses, road trucks, construction site trucks, all-wheel-drive vehicles, municipal vehicles (garbage collection, etc.) with a wide variety of chassis, drives, axles and brakes were installed. Corresponding components could often be exchanged between a large number of similar vehicles, which increased the series production and subsequently made it possible to limit production costs and spare parts prices.
Semi-trailer motorhome
As recently as 1997, the OM 404 engine with 324 kW (440 hp) was used to drive the world's largest mobile home .