MAN L2x6V 17.5 / 18
From the companies that were producing heavy rail diesel engines before the Second World War , MAN went its own way to master the transition from the six-cylinder in-line engine ready for series production to the twelve-cylinder V-engine.
history
In 1934 the engine L2 × 6V 17.5 / 18 appeared for the first time with the railcar 137 074 , which basically consisted of two V-shaped six-cylinder in-line engines as naturally aspirated engines . The two crankshafts were coupled by spur gears and led to a common output. As with the engines from Maybach-Motorenbau , this engine was mounted in a subframe and suspended in three points in the motor vehicle bogie. On January 1, 1937, a total of 46 of these so-called twin-shaft motors were in the inventory of the Deutsche Reichsbahn . Although the structure is completely different, machine bogies from Maybach could be exchanged for those from MAN. A twelve-cylinder, four-stroke, single-shaft engine with the designation MAN L 12V 17.5 / 18 appeared at MAN as early as 1935 . While the first two-shaft motor in the 137 074 had to be repaired after 11,000 kilometers and exchanged for a different type in 1939, the other two-shaft units were only exchanged for replacement motors after the Second World War. In addition to the naturally aspirated version, MAN produced a more powerful version of the engine with engine charging and the name MAN L2x6V 17.5 / 18A .
Structure and components
Basic structure
The housing of the engine was a welded construction and consisted of cast steel parts for the transverse walls of the crankcase and of sheet steel. The two crankshafts were each supported seven times in plain bearings. Compared to the test model installed in the 137 074, the bearing clearance was slightly increased in the other motors. For this, a more powerful lubricating oil pump had to be installed. The lubricating oil supply was 65 kg and was carried in the oil pan , which was made of sheet steel and light metal . The design as a two-shaft motor with a common output shaft required special measures to suppress impacts and undesirable torsional vibrations. For this purpose, the transmission gears were connected to the crankshaft by ring-shaped spring bodies, which were supported in the crankshaft flanges and in the gear bodies.
The crankshaft was made of special steel and was case-hardened . The connecting rods were made of chrome-nickel steel and were mounted on the crankshaft with lead bronze bearings. The bearing on the piston pin was carried out with bronze bearings. Various tests were carried out with these bearings, of which the version with a support shell made of steel and centrifuged bronze ( Thermodur bearings) proved to be the best. That is why this bearing design was changed for all engines in the repair shop .
The light metal pistons were made of an aluminum alloy and connected to the connecting rod by a pin that was firmly seated in the piston. Each piston had four sealing rings and two oil control rings . There were two intake and two exhaust valves per cylinder. The valves had a diameter of 62 mm and were controlled by rocker arms from the overhead camshaft . The camshaft was driven from the crankshaft by a timing chain and gears.
The cylinder liners were made of steel tubing. They were screwed to the cylinder cover and passed through a ring in the crankcase that allowed the cylinder liners to expand axially downwards.
Fuel system and engine control
The engine works with direct fuel injection. For this purpose, a separate MAN injection valve was used for each cylinder , which was replaced by Bosch ones in 1939 . The injection took place through an eight-hole nozzle with a pitch circle diameter of 0.22 mm under an injection pressure of 200 bar. The fuel delivery to the injection pumps was carried out by a double diaphragm pump. The fuel required for operation was carried in three 330-liter containers.
The diesel engine was controlled via speed adjustment in five stages. In addition, there was a maximum speed limit for 1,600 revolutions per minute. The speed adjuster was driven by an electric motor. The transmission to the governor linkage was carried out by a servo piston, which was subjected to the engine lubricating oil pressure. The engine was started electrically by a starter or the main generator. To switch off the engine, the servo piston was depressurized using a shut-off magnet, thus interrupting the fuel supply.
Cooling, lubrication, air system
The engine was water-cooled. The re-cooling of engine lubricating oil got an oil cooler of Windhoff . The cooler was mounted in the machine bogie and cooled by a fan wheel that was driven by the engine.
The spur gears driven by the crankshaft drove a single-stage gear pump for the lubrication system of the bearings, connecting rods and cylinders. At the same time, prelubrication was planned before starting to avoid starting the engine with only partially lubricated bearings.
The combustion air required for the diesel engine was sucked in through openings on the sides of the vehicle and flexible ducts via oil-wetted filters. The combustion exhaust gases were directed to the exhaust hood on the roof centrally above the engine.
Technical specifications
| Parameter | unit | value | comment |
|---|---|---|---|
| rated capacity | kW | 309 | 420 hp |
| Rated speed | min -1 | 1,400 | |
| Idle speed | min -1 | 700 | |
| Cylinder bore | mm | 175 | |
| Piston stroke | mm | 180 | |
| Total stroke volume | l | 51.96 | |
| Compression ratio | 13.5 | ||
| mean piston speed | m / s | 8.4 | |
| medium work pressure | bar | 5.19 | |
| Maximum ignition pressure | bar | 70 | |
| Fuel consumption | g / PSh | 192 ... 195 | |
| Engine ground | kg | 3,330 | |
| Motor length | mm | 2,220 | |
| Engine width | mm | 1,450 | |
| Engine height | mm | 1,475 | |
| Purchase price with accessories | Reichsmark | 33,500 |
Vehicles equipped with the engine for delivery
| model series | first delivery | Reichsbahn sketch sheet or type designation | Power transmission | Vehicle received | comment |
|---|---|---|---|---|---|
| DR 137 074 | 193 | Railcar with an Essen layout | electric | n | |
| DR 137 094 to 110, 137 164 to 223 | 1935 | Railcar with a standard layout | electric | j | Stralsund depot |
| DR 137 160 and 161 | 1937 | Railcar with a standard layout | hydraulic | n |
Operating experience
Apart from problems with the 137 074 , the engines are ready for operation. The engines were only replaced with engines from Maybach after the Second World War .
The weak point of the engines was the double design of the crankshaft with the common output, which required more material and maintenance.
literature
- Heinz R. Kurz: "The railcars of the Reichsbahn-Bauarten", EK-Verlag, Freiburg 1988, ISBN 3-88255-803-2
Individual evidence
- ↑ a b Heinz R. Kurz: "The railcars of the Reichsbahn-Bauarten", EK-Verlag, Freiburg 1988, ISBN 3-88255-803-2 , page 298
- ^ Heinz R. Kurz: "The railcars of the Reichsbahn-Bauarten", EK-Verlag, Freiburg 1988, ISBN 3-88255-803-2 , page 295
- ^ Heinz R. Kurz: "The railcars of the Reichsbahn-Bauarten", EK-Verlag, Freiburg 1988, ISBN 3-88255-803-2 , page 281