Benz OB 2

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Benz & Cie.

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OB 2
Production period: 1923-1928
Manufacturer: Benz & Cie.
Working principle: diesel
Motor design: R4
Valve control: OHV
Displacement: 8836 cm 3
Mixture preparation: Pre-chamber injection
Engine charging: no
Power: 33-37 kW
Previous model: none
Successor: OM 5

The OB 2 from Benz & Cie. is the first diesel engine developed for installation in a truck . It was presented to the public in Amsterdam in February 1924. He was replaced by the OM 5 in 1928 .

Background and development

Even Rudolf Diesel , the inventor of the diesel engine wanted to use diesel engines as a vehicle drive. During Diesel's lifetime, however, the diesel engine was only used as a stationary and marine engine because of the internal mixture formation that was technically difficult to solve . There were as yet no pumps that could both meter the fuel accurately enough and build up the required high injection pressure. Diesel separated the two functions: a metering pump delivered the fuel, which was then blown into the cylinder with compressed air. For this reason, diesel engines had a large and heavy compressor in the early days, so that diesel engines were hardly considered as engines in light vehicles such as trucks and passenger cars were out of the question. The engineer Prosper L'Orange solved the problem of the mixture preparation in 1909 with the pre-chamber injection , which, however, took a few years to reach series production as there were no suitable injection pumps. Kurt Eltze further developed the pre-chamber engine after L'Orange left Benz. The first production-ready pre-chamber diesel engine is of the two-cylinder engine of the Benz-Sendling S 6 with 5726 cm 3 capacity and a rated power of 25 HP (18 kW) at 800 min -1 , which was first put into operation in 1922 and 1923 went into mass production.

Work on a truck diesel engine began in 1922. A Benz chassis of the type 5K3 , a truck with a gasoline engine, was the test vehicle . In September 1922 the first type of OB 2 ran on a test bench; three pre-production engines were built for testing in the truck. They developed a power rating of 45 HP (33 kW) at 1000 min -1 . These engines proved themselves well, so that on April 14, 1923, series production was decided. The engine was ready for series production at the end of August 1923. He made 50 hp (37 kW) at 1000 min -1 . The engine had a major influence on the operating costs of the truck, which could be reduced by 86% compared to a truck with a gasoline engine. The first buyer of a truck equipped with OB 2 was Robert Bosch . The OB 2 was a great economic success for Benz & Cie. though not. Fewer than 100 Benz diesel engines were sold by 1926; by 1928 there were 631 two- and four-cylinder units. The breakthrough of the diesel engine came in 1928 with the OM 5 .

technology

OB 2 is a straight four - four stroke - diesel engine with indirect injection , Overhead valves and water cooling . With a cylinder bore of 125 mm and a piston stroke of 180 mm, the engine has a displacement of 8836 cm 3 . Its performance is 50 hp (37 kW) at 1000 min -1 indicated. It is designed for operation with lignite tar oil , but can also be operated with gas oil , petroleum , Texas oil and paraffin oil .

With OB 2, the individual cylinders are placed on the crankcase , and the cylinder heads are also individual. The flywheel is mounted outside the crankcase. Each cylinder has two valves , which are actuated by a camshaft below via push rods and rocker arms . The fuel is delivered to the injection nozzles by an in- line injection pump and injected into antechamber . The combustion air enters the intake manifold through an air filter , which is common to all four cylinders and is screwed onto them. On the same side as the intake manifold is the water line from the radiator to the cylinders. It has a branch for each cylinder that enters the cylinder head from above next to the cylinder head cover. On the other side of the engine, the common exhaust manifold is bolted to the four cylinders. The bumpers move between the exhaust manifold and the cylinders .

swell

Web links


Timeline of the Daimler-Benz diesel engines up to 1945
Number of cylinders design type Displacement (l) 1920s 1930s 1940s ...
0 1 2 3 4th 5 6th 7th 8th 9 0 1 2 3 4th 5 6th 7th 8th 9 0 1 2 3 4th 5
1 Lying 3.4 OE engine
4.2 OE engine
2 In-line engine 5.7 S6 engine
4th 2.6 OM 138
3.8 OM 59
4.9 OM 65
8.8 OB 2
6th 7.3 OM 67
7.4 OM 67
8.6 OM 5
10.3 OM 79
11.3 OM 57
12.5      
OM 54
12 Boxer engine 30.2 OM 807
V engine 30.5 OM 85
OM 86
Legend: Benz engines Daimler-Benz engines