Locomotive frame
The locomotive frame is the main load-bearing component of locomotives from the time of the beginning of locomotive construction up to the construction form of the self-supporting locomotive body . It is the carrier for the drive and auxiliary units as well as the superstructures. It rests with the load of all components on the attached to it drive and transfers the tensile forces. The locomotive frame is particularly stressed in everyday life by the buffer impacts and the tensile or compressive force, a load that should not be underestimated occurs when the locomotive or the simple frame is lifted by bending. Due to the sinusoidal course , a load on diagonal stiffness occurs.
Classification of the frame
Classification according to the intended use
Locomotive frames are subdivided for use in the various types of locomotive construction. A distinction is made between frames for frame locomotives and frames for bogie locomotives. The frames for the frame locomotives are divided into inner frames and outer frames. The majority of locomotive designs for steam locomotives had inner frames. In favor of this construction were the better option of frame cheek stiffening and various other operational or structural reasons, such as better detection of possible wheel damage or, in the case of steam locomotives, the elimination of the axle cranks required for the outer frame, the so-called Hall cranks . Well-known representatives of outer frame locomotives are the Saxon IK , the ČSD series 324.3 or the MAV series 220 and 377 . For electric locomotives , the outer frame were more common. The inner frame was mostly owned by the rod locomotives . The single-axle locomotives had and have an external frame as a bogie construction to better accommodate the single-axle drive . The DR series E 16 with the Buchli drive was an exception . In the case of diesel locomotives , the frame locomotives preferably had inner frames.
Bogie locomotives, on the other hand, have bridge frames in which, in addition to the frame structure, there is also the bracket for the pivot to guide the bogies . The frames for the bogies were primarily designed as external frames. Exceptions were earlier DB designs such as the V 80 and V 200 .
Classification according to the construction
Depending on the construction, a distinction is made between bars , sheet metal and cast steel frames. In the time up to 1945, the bar frame was predominantly used in steam locomotive construction, the sheet metal frames were of secondary importance for locomotives. Sheet metal frames were primarily used for diesel and electric locomotives and steam locomotives after 1945. This construction was easy and cheap to manufacture, especially in combination with the welding technology . The cast steel frame was used on some steam locomotives operated by private railways in the USA . Are known z. B. the J series of the Norfolk and Western Railway .
In the period up to 1945, the frames were preferably manufactured in the individual parts riveted and screwed together. Welding only appeared on a large scale after 1945. With the transition from the locomotive constructions to the self-supporting construction , the question of the frame construction became superfluous.
Measurement of the frame after manufacture and repair
The locomotive frames have to be measured for the first time after manufacture and after reconditioning for each general inspection . In the steam locomotive era, this was still done using conventional mechanical measuring methods. The frames for diesel and electric locomotives and for the steam locomotives with roller bearings in the connecting rods require even greater measuring accuracy, so that the optical-mechanical measuring methods for frame measurement are necessary here.
To measure, the frame is placed on height-adjustable supports and leveled. It must be ensured that it cannot sag when the axle fork stays are removed. For the measurement, certain original dimensions had to be checked and documented in the frame measurement sheet. Particularly important here were the steam locomotives
- the cylinder diameter,
- Axle bearing guide and slide plate dimensions,
- Position of the axle fork stays in the form of height and width,
- Distance between the center of the driving axle and the center of the cylinder in the longitudinal direction,
- Distance from the center of the frame to the center of the cylinder in the transverse direction,
- lateral deviation of the cylinder center at the height of the driving axis,
for these dimensions there were nominal dimensions and tolerances that absolutely had to be adhered to. In diesel locomotives, especially with rod locomotives, the jackshaft bearings, the horizontal distance between the sliding blocks in the axle bearing cutout, the spacing from the center of the jackshaft bearing to the first center of the axle bearing and the center of each axle, and the outer distance between the axle bearing sliding jaws from the center of the frame were important. The center of the axle bearings could be determined with micrometers which were screwed into the frame of the axle bearing guides. Here, the horizontal and vertical center planes of the axes were determined by means of a circular stop and measuring centers, depending on the center of the jackshaft bearing and the spacing. They served as a starting point and reference point for all frame measurements.
Checking the frame for resilience
Every locomotive frame was subjected to various stress tests during manufacture; After assembling the finished car body of the EM 475.0, the entire body without bogies was subjected to a vertical load of 30 t and a horizontal load of 70 t, and then the car body was examined for any deformations and dents. Other tests were carried out as part of vehicle registration; For example, several test loads with a maximum compressive force of 200 t were tested on the frame of the DB series 151 in a test facility, with no permanent deformations being found. The entire locomotive body of the HGe 4/4 II including the welded bridge frame was tested with a central pressure of 100 t. Of course, such tests did not yet reflect real railway operations.
In earlier times there were no test options for such static tests in the workshops and repair shops; Tests could only be carried out with frame models, whereby these tests came very close to real everyday operation. For the frames of the DR series 52 , static tests, driving tests and tests of fatigue strength were carried out by the State Materials Testing Office Berlin-Dahlen. The possibility of the testing machines had to be taken into account for the tests. For example, frame parts were provided by the manufacturer for the static tests, all of which included an axis section. These frame parts were clamped in the tensile testing machine and subjected to loads of up to 97 t. The stresses here were up to 180 N / mm² in the area of the axis cutouts. For the driving tests the usual driving tests of the Lokomotiv-Versuchsamt Grunewald were used. Twelve dynamic strain gauges were attached to the locomotive to be tested at various points on the locomotive frame and the loads obtained were transferred to oscillograms . The driving tests were carried out with 100 test drives on a 100 m long section on the open road at different speeds and loads.
The fatigue strength tests were carried out on high-frequency pulsators . Due to the size of the machines, it was not possible to use real dimensional images like in the tensile test, reduced models with 16%, 32% and 57% of the model size had to be used and the stress results obtained had to be converted to the original scale using double logarithms. The conversion values were the operational strength / calculated from 170 N mm². During the tests, a frame side of a model broke after 443,000 load changes , the reason being a material defect.
Refurbishment of the framework
The reconditioning of the locomotive frame had to be carried out at every scheduled inspection, which was carried out every 1.5 years, and in the event of unplanned events such as derailment or a rear-end collision in the repair shop . The required work steps are documented separately in the articles of the bar frame and sheet metal frame .
Web links
literature
- Karl-Ernst Maedel , Alfred B. Gottwaldt : German steam locomotives , Transpress Verlag , Berlin, ISBN 3-344-70912-7
- Manfred Weisbrod, Hans Müller, Wolfgang Petznick: Steam locomotive archive, series 01–99 , Transpress-Verlag, Berlin 1976
- Wilfried Rettig: The RAW Görlitz , EK-Verlag, Freiburg, ISBN 978-388255-771-8
- Wolfgang Messerschmidt: Lokomotivtechnik im Bild , Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3
- State Materials Testing Office Berlin-Dahlem: Stress measurements on the screwed sheet metal frame of the 52 series , Berlin 1944
Individual evidence
- ^ Wolfgang Messerschmidt: Lokomotivtechnik im Bild , Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3 , page 163
- ↑ Internet site about steam locomotives using cast steel frames
- ^ Wilfried Rettig: Das RAW Görlitz , EK-Verlag, Freiburg, ISBN 978-388255-771-8 , page 49
- ↑ Website about the development of the EM 475.0 series on www.prototypy.cz, section Zkoušky jednotky EM475.001 / 02
- ^ Wolfgang Messerschmidt: Lokomotivtechnik im Bild , Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3 , page 165
- ↑ Wolfgang Messerschmidt: Lokomotivtechnik im Bild , Motorbuchverlag, Stuttgart 1991, ISBN 3-613-01384-3 , photo on page 166
- ↑ State Material Testing Office Berlin-Dahlem: Stress measurements on the screwed sheet metal frame of the 52 series , Berlin 1944, page 2
- ↑ State Material Testing Office Berlin-Dahlem: Stress measurements on the screwed sheet metal frame of the 52 series , Berlin 1944, page 5
- ↑ State Material Testing Office Berlin-Dahlem: Stress measurements on the screwed sheet metal frame of the 52 series , Berlin 1944, page 8