Sheet metal frame

from Wikipedia, the free encyclopedia

A sheet metal frame is a special design of the locomotive frame and was designed as a simpler sheet metal construction compared to the bar frame also used in steam locomotive technology . While the bar frames had a frame width of around 100 mm, the sheet metal frames were around 28 mm thick for demanding constructions. The development of the different frame shapes came about because the mass of the locomotives was constantly increasing. The prescribed total mass for the Rainhill locomotive race was 6 t, while the Badenia locomotive from 1842 already weighed 16.2 t. Powerful locomotives from around 1900, on the other hand, had a mass of around 80 t. In contrast to bar frames, sheet metal frames were also used in diesel and electric locomotives . Sheet metal frames are cheaper to manufacture than bar frames.

Use with the different types of traction

Use in steam locomotives

Original sheet metal frame of a Heeresfeldbahn locomotive HF 110 C in riveted construction

All steam locomotives from the time before 1900 were equipped with sheet metal frames after it was recognized that the wooden frames of the first locomotive constructions only allowed low loads and were not durable. At the end of the Länderbahn era , locomotives with sheet metal frames were used in rows that were less loaded and designed as two-cylinder engines. There have also been constructions with sheet metal frames for locomotives in the demanding express and freight train service. Outstanding examples are Class C and Class K of the Royal Württemberg State Railways , which have proven themselves in operational service and have been in operation for around 40 years. These and other constructions required special maintenance cutouts for the inner engines. There have long been reservations about the elasticity of the frame, which was greater in the bar frame.

With the construction of the DR class 52 , the pre-war Deutsche Reichsbahn built a locomotive for higher loads with a sheet metal frame, initially in a bolted design. Cost reasons and the planned short period of use led to rethinking. Locomotives of this design have proven themselves in operational service, and only locomotives with sheet metal frames were used in the reconstruction of the class 52 to the DR class 52.80 . When the new locomotives with mostly two-cylinder engines appeared after the Second World War , only sheet metal frames in welded construction were used for these locomotives.

Use in electric locomotives

Typical sheet metal frame construction for the E 50 42 electric locomotive

On the photo of a sheet metal frame frame locomotives to see the electric so in the early locomotives with rod drive up was used in the late 1920s. The changeover to single-axis drives subsequently required the use of external frames. The frame for the E 19 was completely welded with 25 mm thick continuous beams and cross connections and carried the superstructures, the transformer , the traction motors and the auxiliary machines that were bolted to the central frame.

In later designs of bogie locomotives , the frames were designed as bridge frames and, in addition to the above-mentioned superstructures, had cross members for support on the bogies . At the beginning the frame carried the vehicle alone, later the floor frame and box body were designed as a joint, self-supporting structure . These vehicles had a continuous floor pan, which gave them the necessary strength. The welding of the floor frame and box walls made it possible to absorb the vertical (due to the load of the locomotive) and horizontal (due to the load during operation) forces. The locomotive boxes show this, for B. the DR series 243 , which received beads to reinforce the side walls . Rolled square profiles were used for the solebar and the girders of the transformer of the DB series 151 .

Today's locomotives have a self-supporting car body in a welded construction. The load-bearing parts of the locomotive body are vertical and inclined profiles. As with the DB series 101, the outer skin of these machines is only 3 mm thick.

Use with diesel locomotives

Most modern diesel locomotives have a welded frame. There were differences in the design of the locomotives as front-mounted or box locomotives . In front-mounted locomotives such as the DR series V 60 , the frame is a welded construction, consisting of frame cheeks, transverse reinforcements, axle bearings and jackshaft bearings. The buffer beams are screwed to the ends of the frame. The superstructures are screwed to the frame so that the forces loading the frame cannot be passed on to the drive system.

In the case of the box locomotives, the bridge frame and the box body are almost exclusively designed as welded sheet metal girder structures, as is the case with the V 200 . The origin of this construction principle comes from the railcar construction from the 1930s. Here the locomotive body with the frame are a load-bearing unit. The locomotive body is clad with sheet metal with a sheet thickness of only 2 mm. The drive unit was mounted on a separate support frame, and the fuel tanks were screwed to the frame.

Manufacturing peculiarities

Photo of a sheet metal frame of the Heeresfeldbahn locomotive HF 110 C as a replacement welded construction

A structure of the sheet metal frame is described here using the frame of the series 17.8 of the Royal Saxon State Railways . The frame cheeks had a thickness of 30 mm and a maximum height of 950 mm. The frame cheeks were set wide apart, the largest clear width was 1250 mm. The high width was chosen to gain space for as wide a standing kettle as possible . The clear width was chosen so large that the frame sides were up to 25 mm away from the wheel tire level . In the area of ​​the front bogie, the clear width was reduced to 1070 mm.

The frame cheeks were connected to the buffer beam , the cylinders, the axle bearing guides, several cross struts and pendulum plates, the driver's cab bracket and the coupling box for the tender. At first the frame parts were riveted, in the case of the DR series 52 they were screwed together, and after the Second World War they were manufactured using a welded construction. The production by welding is the most effective and cheapest method of the production of all locomotive frames, due to the relatively large sheet thickness the welding distortion is not insignificant, which requires a lot of experience in processing. Due to the welding, the entire frame construction was more rigid, which could have a negative effect on the frame in poor track conditions. Due to the lower sheet thickness compared to the bar frame, the sheet metal frames generally managed without large, mass-saving cutouts.

Maintenance specifics

For each scheduled inspection, which was carried out every 1.5 years in the repair shop , the condition of the sandblasted frames had to be assessed and the corresponding work steps had to be determined. Naturally, the most frequent causes of defects were the weld seams with the greatest load and the shortest weld seam length. These were primarily the connections with the axle bearing sliding jaws. Frame cracks were not uncommon, especially like they stepped on to the Achsausschnitten with small fillets. Cracks had to be marked and welded. The axle fork bridges had to be adjusted and the holes for the fitting screws worked up. After the refurbishment, the frame had to be measured.

Unplanned events such as derailment or a rear-end collision resulted in an unscheduled maintenance stage with a general assessment and measurement.

Web links

literature

Individual evidence

  1. ^ Manfred Weisbrod, Hans Müller, Wolfgang Petznick: "Steam locomotive archive, series 01-39", Transpress Verlag Berlin, 1976, description of the locomotive series 18.1
  2. ^ Karl-Ernst Maedel, Alfred B. Gottwaldt: "Deutsche Dampflokomotiven", Transpress Verlag, Berlin, ISBN 3-344-70912-7 , page 32
  3. ^ A b Manfred Weisbrod, Hans Müller, Wolfgang Petznick, "Steam Locomotive Archive, Series 01-99", Transpress Verlag, Berlin, 1976
  4. ↑ a b c Wolfgang Messerschmidt: "Lokomotivtechnik im Bild", Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3 , page 165
  5. ^ Wolfgang Messerschmidt: "Lokomotivtechnik im Bild", Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3 , page 166
  6. ^ Jürgen-Ulrich Ebel: "Sächsische Schnellzuglokomotiven Volume 1", EK-Verlag, Freiburg 1997, ISBN 3-88255-117-8 , page 128
  7. ^ Wilfried Rettig: "Das RAW Görlitz", EK-Verlag, Freiburg 2013, ISBN 978-388255-771-8 , page 49