BS EN 16452:2015 pdf free

BS EN 16452:2015 pdf free.Railway applications – Braking – Brake blocks.
5 Overall requirements
5.1 Deviations from requirements
If deviating from some points of the requirements of this standard for a particular assessment, theses deviations shall be reported and explained. The influence on the assessment of the brake block in terms of the acceptance criteria shall be evaluated and recorded. The outcome of this study shall be considered as an integral part of the requirements of this standard when applied to the assessment process of the brake block.
5.2 Functions
The brake block is to be used as part of the friction brake of a vehicle. It shall provide the performance
specified, in terms of stopping distance for instance, and in doing so shall fulfil the following requirements:
— create a braking moment or torque;
— facilitate, by frictional engagement with a wheel tread, the conversion into heat of the kinetic and potential energy involved in retarding the vehicle or vehicles which is/are attributed to the use of the tread brake;
— act as part of a holding or parking brake by frictional engagement with a wheel tread.
In achieving the above requirements, the brake block and the wheel shall not suffer damage or degradation other than normal wear and tear.
The brake block shall be considered along with the wheel tread as a friction pair.
5.3 Operational criteria
5.3.1 Friction material performance
The design and manufacture of the brake block shall, for all intended operating conditions and vehicle rescue and recovery conditions, take into account the following criteria for friction material performance:
— all levels of stopping and slowing distances and immobilization braking specified;
— all levels of retardation specified;
— the initial speed of braking for the vehicle in question;
— the braked mass, in tare and laden conditions;
— the quantity of brake energy to be converted and its rate of conversion and dissipation;
— the range of specific pressure of the brake block friction surface on the wtieel tread:
— the form and condition of the wheel tread;
— the type of material used in the manufacture of the wheel tread;
— the temperature of the wheel tread;
— the deformation of the wheel under thermal load;
— friction property variation as a function of brake block and wheel tread bedding and conditioning thereafter:
— friction property variation as a function of brake block and wheel tread according to various climatic conditions;
— signalling performance from the interaction of brake block, wheel and rail.
5.3.2 Service performance
The design and manufacture of the brake block shall, for all intended operating conditions and vehicle rescue and recovery conditions, take into account the following criteria for service performance:
— the need to prevent the detachment of any part of the friction material from the brake block back plate throughout its useable thickness;
— unless specifically permitted, the friction material shall be capable of being worn down to a thickness of 10 mm at the thinnest point excluding the back plate, without mechanical degradation of the friction material or the back plate coming into contact with the wheel tread;
— the need to allow interchangeability between brake b’ocks of the same friction characteristics, and to
avoid interchangeability between brake blocks of different friction characteristics;
— the integrity and wear rate of the brake block friction material and wheel tread;
— the need to prevent permanent deformation of the brake block back plate throughout the useable thickness of the friction material;
— the need to comply with environmental and health requirements.BS EN 16452 pdf download.