BS/EN 15328-2020 pdf download.Railway applications – – Brake pads.
During continuous brake applications, after 10 s the instantaneous coefficient of fnction shall stay inside the band defined by Pmin = 0,250 and Pmax 0,500.
After 2 minutes the instantaneous coefficient of friction shall not vary more than 0,05 during any minute and the coefficient of friction shall stay inside the band defined by Pmjn = 0,250 and = 0,500.
The brake pad wear during any continuous brake application, including the stop brake application thereafter, shall not exceed 1 mm. The wear in mm can be calculated from the weight differences before and after the continuous brake application.
5.5.6 Criteria for bedding brake applications
The nominal coefficient of friction of the bedded state shall be defined as the average of measured mean coefficients of friction 1m of the last 5 braking stops carried out during the bedding section.
During the bedding-in phase, the mean coefficients of friction shall not exceed the following variations from the nominal value of the bedded state:
—±30% from the 11th bedding-in brake application until 30% of number of the bedding-in applications are finished;
— ± 15 % during the rest of the bedding-in process.
5.6 Requirements and optional test programs for brake pads for coaches
5.6.1 General
The frictional requirements for brake pads in coaches used in generic operation are described in 5.6.2 to 5.6.6. The optional test programs are defined in SI.I and S2.1 for organic material and TI and T2 for sintered material, and may be used instead of ener’ class CO (see Annex C).
5.6.2 Tolerance ranges
The tolerance ranges for the instantaneous and mean coefficients of friction on a dry brake disc are given for the respective applications in the figures of the corresponding annexes. The instantaneous and the mean coefficients of friction measured in the test bench tests shall be documented in the appropriate tolerance diagrams. For the highest nominal application forces of the test program the mean coefficients of friction are summarized in a separate tolerance diagram and documented in tabular form. The average value of these mean coefficients of friction at a speed of 120 km/h at the highest nominal application force (excluding brake application with high Initial temperatures) shall not vary more than 10 % upwards or 5% downwards from the nominal coefficient of friction given in the tolerance diagram of the respective test program. At speeds above 120 km/h, the average values of these mean coefficients of friction shall not vary more than 10% upwards or 10% downwards from the nominal coefficients of friction.
After 2 minutes the instantaneous coefficient of friction shall not vary more than 0.05 during any minute and the coefficient of friction shall stay inside the band defined by = 0.250 and Pmax = 0,500.
5.6.4 Criteria for bedding brake applications
The mean coefficient oi friction of the bedded state shall be defined as the average of measured mean coefficient of friction of the last S braking stops carried out during the bedding section.
During the bedding-in phase, the mean coefficients of friction shall not exceed the following variations from the nominal value of the bedded state:
—±30% from the 11th bedding-in brake application until 30% of number of the bedding-in applications are finished;
— ± 15 % during the rest of the beddingin process.
5.6.5 Coefficient of friction under high thermal load
For brake applications to a stand, which are done from a high initial temperature (approximately 140 °C, excluding brake application after continuous brake applications and for two consecutive emergency brake without cooling time), the mean coefficient of friction under otherwise similar conditions shall not vary by more than ± 15 % from the average of the mean coefficients of friction of brake applications initiated from the cold and dry condition.
5.6.6 Coefficient of friction under wet conditions
In wet conditions, with the highest nominal application force of test program 52.1 and T2 the mean coefficient of friction shall not vary — all other things being equal — by more than ± 15 % compared with the average of mean coefficients of friction obtained during braking under dry conditions. The mean coefficients of friction of the other brake applications to a stand of this test program shall not underrun the absolute value Of 14m = 0,250 under otherwise similar conditions.
5.7 Geometrical features of the brake pads
5.7.1 Brake pad shape
The SBP shall be designed in accordance with Annex F.
5.7.2 Brake pad wear
The design of the brake pads shall enable them to wear uniformly to a friction material thickness of 5 mm or defined by design specification.
5.7.3 Brake pad fixing.BS/EN 15328-2020 pdf download.