GB 12676-2014Road vehicle -- Braking systems -- Structure, performance and test methods (English PDF)

3.1 Basic terms and definitions

3.1.1 Vehicle type

3.1.1.1 Motor vehicle

With regard to braking system, the vehicles which do not differ in such essential respects as.

3.1.1.2 Trailer

With regard to braking system, the vehicles which do not differ in such essential respects as.

3.1.2 "Braking system" means the combination of parts whose function is progressively to reduce the speed of a moving vehicle or bring it to a halt, or to keep it stationary if it is already halted. The system consists of the control, the transmission, and the brake proper;

3.1.3 "Actuation" means both application and release of the control.

3.1.4 "Transmission device" means the combination of components comprised between the control and the brake and linking them functionally. The transmission may be mechanical, hydraulic, pneumatic, electric or mixed. Where the braking power is derived from or assisted by a source of energy independent of the driver, the reserve of energy in the system is likewise part of the transmission.

3.1.5 "Brake" means the part in which the forces opposing the movement of the vehicle develop. It may be a friction brake (when the forces are generated by friction between two parts of the vehicle moving relatively to one another); an electrical brake (when the forces are generated by electro-magnetic action between two parts of the vehicle moving relatively to but not in contact with one another);

3.1.6 "Different types of braking systems" means systems which differ in such essential respects as.

3.1.7 "Component of a braking system" means one of the individual parts which, when assembled, constitutes the braking system;

4.1 General

4.1.1 Braking system

4.1.1.1 The braking system shall be so designed, constructed and fitted as to enable the vehicle in normal use, despite the vibration to which it may be subjected, to comply with the provisions of this

Standard. The braking response time on vehicles equipped with compressed-air braking systems shall comply with the specifications in Annex B. The energy sources and energy storage devices of braking system shall comply with the specifications in Annex C. The spring braking system shall comply with the specifications in Annex D.

4.1.2 Functions of the braking system

4.1.2.1 Service braking system

The service braking system shall make it possible to control the movement of the vehicle and to halt it safely, speedily and effectively, whatever its speed and load, on any up or down gradient. It shall be possible to graduate this braking action. The driver shall be able to achieve this braking action from his driving seat without removing his hands from the steering control.

4.1.2.2 Secondary braking system

The secondary braking system shall make it possible to halt the vehicle within a reasonable distance in the event of failure of the service braking system. It shall be possible to graduate this braking action. The driver shall be able to obtain this braking action from his driving seat while keeping at least one hand on the steering control. For the purposes of these provisions it is assumed that not more than one failure of the service braking system can occur at one time.

4.1.3 Connections, for compressed-air braking systems, between power-driven vehicles and

trailers

4.1.4 Provisions for the periodic technical inspection of braking systems

4.1.4.1 It shall be possible to assess the wear condition of the components of the service brake that are subject to wear e.g. friction linings and drums/discs (in the case of drums or discs, wear assessment may not necessarily be carried out at the time of periodic technical inspection). The method by which this may be realized is defined in paragraphs 4.2.1.11b) and 4.2.2.8b) of this

Standard. Other friction linings meeting the requirements of Annex G may be optional.

4.1.5 Complex electronic control system

The requirements of Annex H shall be applied to the safety aspects of all complex electronic vehicle control systems which provide or form part of the control transmission of the braking function included those which utilize the braking system(s) for automatically commanded braking or selective braking. However, systems or functions, which use the braking system as the means of achieving a higher level objective, are subject to Annex H only as far as they have a direct effect on the braking system. If such systems are provided, they shall not be deactivated during testing of the braking system.

4.2 Characteristics of braking systems

4.2.1 Vehicles of categories M and N

4.2.1.1 The set of braking systems with which a vehicle is equipped shall satisfy the requirements laid down for service, secondary and parking braking systems.

4.2.2 Vehicles of category O

4.2.2.1 Trailers of category O1 need not be equipped with a service braking system; however, if a trailer of this category is equipped with a service braking system, it shall satisfy the same requirements as a trailer of category O2.

5.1 Test Requirements

5.1.1 General Requirements

5.1.1.1 The performance prescribed for braking systems is based on the stopping distance and/or the mean fully developed deceleration. The performance of a braking system shall be determined by measuring the stopping distance in relation to the initial speed of the vehicle and/or by measuring the mean fully developed deceleration during the test.

5.1.1.2 The brake shall be subjected to run-in in compliance with the running-in procedures stipulated by the manufacturer or the following requirements.

5.1.1.3 The stopping distance shall be the distance covered by the vehicle from the moment when the driver begins to actuate the control of the braking system until the moment when the vehicle stops; the initial speed shall be the speed at the moment when the driver begins to actuate the control of the braking system; the initial speed shall not be less than 98 percent of the prescribed speed for the test in question.

5.1.2 Road test conditions for vehicle braking performance

5.1.2.1 The vehicle's condition as regards mass shall be as prescribed for each type of test and be specified in the test report

5.1.2.2 The test shall be carried out at the speeds prescribed for each type of test; if the maximum design speed of a vehicle is lower than the speed prescribed for a test, the test shall be performed at the vehicle's maximum speed;

5.1.2.3 During the tests, the force applied to the control of the braking system in order to obtain the prescribed performance shall not exceed the maximum force laid down for the test vehicle's category;

5.1.2.4 The road shall have a surface affording good adhesion, unless specified otherwise;

5.1.2.5 The gradient on any 50 meters of longitudinal surface on the test road shall be less than 1 percent. The parking test gradient shall follow the relevant provisions. The gradient of road crown shall be less than 2 percent.

5.1.4 Type-O test (ordinary performance test with brakes cold)

5.1.4.1 General

5.1.5 Type-I test (fade test)

5.1.5.1 Repeated braking test

5.1.5.1.1 The service braking systems of all power-driven vehicles shall be tested by successively applying and releasing the brakes a number of times, the vehicle being laden, in the conditions shown in the Table 3.

5.2.3 Parking braking system

5.2.3.1 The parking braking system shall, even if it is combined with one of the other braking systems, be capable of holding the laden vehicle stationary on an 18 percent up or down-gradient.

6.1 Approval of Vehicle Type

As for a group of vehicle types applied for approval, one or more vehicles having the following characteristics shall be taken as representative (s), which shall undergo all tests specified in this

Standard.

6.2 Extension of Approved vehicle types

6.2.1 In the case of any modification to the braking system of the approved vehicle types, it shall be necessary to apply for extension.

6.22 In case the extension of approved vehicle types complies with the principles in paragraph 6.1, the extension shall be granted.

6.23 In case the extension of approved vehicle types exceeds the range specified in paragraph 6.1, retest shall be performed.