Double buffers system for the improvement of railway vehicles behaviour in curves.

Otlacan, Dimitrie ; Duma, Virgil-Florin ; Kaposta, Iosif 等

1. INTRODUCTION

The joined commissions of experts ORE (ERRI) B12-B36, has recommended (ORE, 1990) the following: 1) to reduce the dynamic elongation efforts, especially at heavy load trains; 2) to diminish from 2000 kN to 1200-1500 kN the compression efforts provided when testing nowadays wagons; 3) to decrease the load of the wagons, a goal that may be reached if: 4) a general use of the hydrodynamic buffers would be achieved; 5) the characteristic of the buffers has to take into account the difference between wagons in the period of testing and those in the period of work (it suggests the use in the shock absorbers with a pneumatic switcher from the second pneumatic link).

[FIGURE 1 OMITTED]

The following conclusions were drawn: 6) the forward increase of the maximum weight and volume of the wagons; 7) the increase of the velocities of the trains; 8) the improvement of the protection of the transported freight, by using long displacement buffers; 9) the decrease of the prices and of the repairs costs; 10) the increase of the total transport distance of the wagons for different items from 100,000 km, nowadays, to 200,000 km, in the future; 11) the conversion (UIC, 1998) to the automatic couple can be done only if a substantial decrease of the costs (from 15.000 DM to 10.000 DM / vehicle) can be achieved; 12) in order to provide the safe pass through curves with a radius <150 m, it is necessary to consider special measures in order to obtain decreased forces between the buffers and the linking system.

2. DEVELOPED SYSTEM: CONSTRUCTION AND CHARACTERISTICS

Recent concerns of the UIC are towards all the aspects related to the construction and use of the wagons, and buffers (Dixon, 1998) are included--regarding the necessity to protect the load and/or the structure of the wagons (UIC 1990, 1998), and the transversal forces generated when passing through curves, forces that have a certain influence on the safety of the transports (ORE 1988, 1989, 1991). The importance of solving these problems are proved by the number of studies developed (ORE 1995a, b, c) or undergoing at ORE.

In order to meet the present and also future requirements regarding the buffers, we have conceived a buffer (Otlacan, 1999) able to satisfy all the specified conditions, performing a development of the hydrostatic technology (Otlacan 2007).The constructive solutions we have developed (Otlacan, 2009) has the purpose of reducing the transversal forces when the wagons pass through the curves.

This was achieved through the hydraulic linking of the compressible fluids from the buffers from the same end of the railway vehicles, as in figure 1. In the situation when the wagons pass through curves, with regard to the radius of the curve and to the characteristics of the wagon, the buffers from but one side of the wagon (the one on the side of the curve) is compressed, and the buffers in the linking system is elongated. In the 32th Report of the experts Commission B36 of ORE, a method of calculus of the total deformations of the spring of the buffers system and of the elongation spring when passing through curves was provided. By example, when passing through curves with a radius of 150 m of wagons on bogies with a length over the buffers of 19.4 m, the entire deformation of the springs is equal to 113.5 mm.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

In figure 2, the forces that appear when passing through curves with a 150 m radius are presented, when the dimension between the centers of the buffers is 19.4 m, for several types of buffers. According to the calculus, the summed deformation of the two springs (including the one of the tensile apparatus) is 113.5 mm. According to UIC 520, the maximum force allowed between the two buffers in order pass safely through curves is equal to 250 kN.

In the case of the system presented in figure 1, when both buffers are compressed, they behave as if they were not linked, while in the case when a single buffer is compressed, at the same deformation, a force half of the previous one is obtained, because the volume of fluid that is compressed is double. Their static diagram will be in this case the improved one presented in figure 3.

3. CONCLUSIONS

The study performed demonstrates the superior characteristics of our developed buffers and of this particular double-device assembly with regard to existing solutions. Our on-going work addresses both the further improvement of these systems and several other applications of these shock absorbers and hydrostatic springs solutions, e.g. in road transport.

4. REFERENCES

Dixon, J. (1998). The shock absorber handbook, Society of Automotive Engineers, Warendale, Pa

ORE B51 RP 25 (1988). Study of feasibility of an automatic draw-only coupler

ORE B36 Report 32 (1989). Characteristics of the buffing and draw gear of wagons to ensure the safe running of long vehicles in small-radius curves, Utrecht

ORE B12 RP 49 (1991). Calculus basics for drawing the graphs of the UIC 530-2, Utrecht

ORE B51 RP 27 (1995a). Design and testing of new draw-gear for wagons

ORE B51 RP 28 (1995b). Testing the life of hydrodynamic and hydrostatic buffers

ORE B51 RP 29 (1995c). Effect of buffer plate shape on confort in coaches

ORE DT 230/B12/B36 (1990). Advancements of the wagons construction technique. Perspectives for the nearby future, Utrecht

Otlacan, D. (1999). Patent RO119142 (WO 03/067116; AU 2001/297520)

Otlacan D. et al (2007). Contributions to the improvement of the dynamic characteristics of the hydrostatic springs, Proceedings of 18th DAAAM International Symposium, Katalinic, B. (Ed.), pp 533 - 534, ISBN 3-901509-58-5, Zadar, October 2007, DAAAM International Vienna

Otlacan D. et al (2009). Contributions to the hydrostatic buffers for railways vehicles, Proceedings of 20th DAAAM International Symposium, Katalinic, B. (Ed.), ISBN 978-3901509-70-4, Vienna, November 2009, DAAAM International Vienna

UIC 577 (1990). Stress of the wagons, 1st Edition

UIC 526-1 (1998). Wagons. Buffers with a 105 mm displacement