BS/EN 15551-2017 pdf download.Railway applications Railway rolling stock – Buffers.
4.4 Long stroke buffer 150 mm
Wagons used for carriage of impact-sensitive goods may be fitted with 150 mm stroke buffers in order to maintain the accelerations exerted on goods at the lowest level possible while complying with the minimum requirements of EN 12663-2.
NOTE The possibilities for use of hydrodynamic buffers are described in Bibliographical Entry [321.
150 mm-stroke buffers are designated by the letter LU.
4.5 Crashworthy Buffers
Crashworthy buffers are identified by an additional designation letter
4.6 Interaction coupling/buffer
To ensure that the train is able to negotiate curves of 150 m radius safely, the static characteristics of draw gears and buffers should be coordinated.
In order to meet this requirement for vehicles, a guideline value of 250 kN for bogie vehicles should not be exceeded for the compression force cia pair of buffers in contact in a curve of 150 rn.
To determine the compression force for vehicles, the calculation method shown under Section 3 of RP 32 of ORE B 36 [331 may be used (the method described in this report is also applicable for coaches and locomotives). This calculation method may also allow stress levels to be determined on smaller radius curves. If the coupling practice creates pretension forces, these shall be taken into account.
NOTE I Using the calculation for the curve in according with RP 32 of ORE B 36 [33] also gives confidence for an S curve of 150 m with an intermediate straight of 6 m.
NOTE 2 When EN 16839 is published, these paragraphs or parts of paragraphs will not be relevant.
When a non-metallic insert or head is provided on one of the two buffers per wagon end, it should be placed diagonally according to Figure 2.
Two buffers shall be fitted at each vehicle end with the same elastic system, category, head dimension, stroke and type of housing.
5.2 Fixing on vehicle and Interchangeability
The buffers shall be fixed to the vehicle headstock by means of four bolted M 24 fasteners.
For 105 mm and 150 mm stroke buffers for freight wagons, when interchangeability is required the dimensions and spacing of the holes needed on the buffer support plate for its fixing on the headstock are given in Figure 3.
The 105 mm stroke buffer flange shall cover the location for the pin (see cross section Al — Al of Figure 3). This pin is to prevent the fixing of a 105 mm stroke buffer where a long stroke buffer is required.
The 150 mm stroke buffer flange shall have a location for the pin (see location and dimension of the flange in cross section A2 – A2 of Figure 3).
For crashworthy buffers or buffers which form part of a combined system consisting of a special buffer and a deformation element, a different mounting of the buffers (e.g. position of flange, bolt diameter, quantity of bolts and their position) may be used, whereupon Figure 3 is not applicable.
NOTE Interchangeability is not required for these buffers.
For friction spring/ring spring and buffer with 105 mm stroke, after 25 mm stroke, the static characteristic could be between 30 kN and 170 kN if the feasibility is confirmed by service experience. The interaction between coupling and the buffer needs further consideration for this configuration.
Tests on hydrodynamic and hydrostatic springs shall also determine whether the reaction force exerted by the buffer at compression of 30 mm, 60 mm and 100 mm depths, respectively remains virtually constant for 10 mm.
5.5.3 Dynamic characteristics
Dynamic characteristics are those obtained when a test vehicle fitted with the buffers to be tested is impacted by another test vehicle.
The values imposed are designed to ensure adequate protection of the passengers, the goods carried and of the vehicle structure against huffing impact, particularly in marshalling yards.
5.5.4 Type testing
The following type tests shall be undertaken:
— dynamic testing as specified in Annex E;
— endurance testing under service load for elastic system as specified in Annex F;
— endurance testing for life-cycle simulation as specified in Annex G.
5.6 Marking
Buffers shall be marked as indicated in Figure 5 and Figure 6. This marking system is also applicable for buffers of 110 mm stroke.
The minimum size of the letters Is defined in Figure 6.
This marking shall be applied during manufacture or inserted on a securely fixed metal plate depending on the method of manufacture.BS/EN 15551-2017 pdf download.