Part 8Braking systems

Part 8—Braking systems This Part sets out the braking system requirements for vehicles to ensure that they can be reliably slowed or stopped even if a part of a braking system fails, and to ensure that a vehicle can be prevented from rolling away when parked. Division 1—Brake requirements for all vehicles 119—Components of a braking system A brake tube or hose fitted to a vehicle must— (a) be manufactured from a material appropriate to the tube's or hose's intended use in the vehicle; and (b) be long enough to allow for the full range of steering and suspension movements of the vehicle; and (c) be fitted to prevent the tube or hose being damaged during the operation of the vehicle by— (i) a source of heat; or (ii) any movement of the parts to which the tube or hose is attached or near. 120—Provision for wear The braking system of a vehicle must allow for adjustment to take account of normal wear. 121—Supply of air or vacuum to brakes air brake compressor, of a vehicle, means a compressor for supplying air to the vehicle's air brakes; compressed air reserve, for a vehicle, means compressed air stored on the vehicle for supplying the vehicle's braking system; condensate drain valve means a device used to remove water from the compressed air reserve for a vehicle fitted with air brakes; governor cut-out pressure, of a vehicle, means the air pressure at which the vehicle's air brake compressor stops supplying air to the vehicle's air brake reservoir; spring brake means a brake using 1 or more springs to store the energy needed to operate the brake; vacuum reserve, in relation to a vehicle, means air at a low pressure stored on the vehicle for supplying the vehicle's braking system. (2) If air brakes are fitted to a vehicle— (a) the vehicle's air brake compressor must be able to build up air pressure to at least 80% of the vehicle's governor cut-out pressure, in not more than 5 minutes after the compressed air reserve is fully used up; and (b) there must be an automatic or manual condensate drain valve at the lowest point of each air brake reservoir in the vehicle's braking system; and (c) any spring brake fitted to the vehicle must not operate before the warning mentioned in rule 128(3)(a) has been given. (3) If vacuum brakes are fitted to a vehicle, the vacuum supply must be able to build up vacuum— (a) to the level when the warning signal mentioned in rule 128(3)(a) no longer operates within 30 seconds after the vacuum reserve is fully used up; and (b) to the normal working level within 60 seconds after the vacuum reserve is fully used up. 122—Performance of braking systems (1) One sustained application of the brake of a motor vehicle built after 1930, or a combination that includes a motor vehicle built after 1930, must be able to produce the performance mentioned in subrules (2) to (7)— (a) when the vehicle or combination is on a dry, smooth, level road surface, free from loose material; and (b) whether or not the vehicle or combination is loaded; and (c) without part of the vehicle or combination moving outside a straight path— (i) centred on the longitudinal axis of the vehicle or combination before the brake was applied; and (ii) 3.7 metres wide. (2) The braking system of a motor vehicle or combination with a gross mass under 2.5 tonnes must bring the vehicle or combination from a speed of 35 kilometres an hour to a stop within— (a) 12.5 metres when the service brake is applied; and (b) 30 metres when the emergency brake is applied. (3) The braking system of a motor vehicle or combination with a gross mass of at least 2.5 tonnes must bring the vehicle or combination from a speed of 35 kilometres an hour to a stop within— (a) 16.5 metres when the service brake is applied; and (b) 40.5 metres when the emergency brake is applied. (4) The braking system of a motor vehicle or combination with a gross mass under 2.5 tonnes must decelerate the vehicle or combination, from any speed at which the vehicle or combination can travel, by an average of at least— (a) 3.8 metres a second a second when the service brake is applied; and (b) 1.6 metres a second a second when the emergency brake is applied. (5) The braking system of a motor vehicle or combination with a gross mass of at least 2.5 tonnes must decelerate the vehicle or combination, from any speed at which the vehicle or combination can travel, by an average of at least— (a) 2.8 metres a second a second when the service brake is applied; and (b) 1.1 metres a second a second when the emergency brake is applied. (6) The braking system of a motor vehicle or combination with a gross mass under 2.5 tonnes must achieve a peak deceleration of the vehicle or combination, from any speed at which the vehicle or combination can travel, of at least— (a) 5.8 metres a second a second when the service brake is applied; and (b) 1.9 metres a second a second when the emergency brake is applied. (7) The braking system of a motor vehicle or combination with a gross mass of at least 2.5 tonnes must achieve a peak deceleration of the vehicle or combination, from any speed at which the vehicle or combination can travel, of at least— (a) 4.4 metres a second a second when the service brake is applied; and (b) 1.5 metres a second a second when the emergency brake is applied. (8) The parking brake of a vehicle or combination must be able to hold the vehicle or combination stationary on a 12% gradient— (a) when the vehicle or combination is on a dry, smooth road surface, free from loose material; and (b) whether or not the vehicle or combination is loaded. Division 2—Motor vehicle braking systems 123—What braking system a motor vehicle must have independent brake, for a vehicle, means a brake that is operated entirely separately from any other brake on the vehicle, except for any drum, disc or part, on which a shoe, band or friction pad makes contact, that is common to 2 or more brakes. (2) A motor vehicle with 4 or more wheels built, or used, mainly for transporting goods or people by road must be fitted with— (a) a braking system that— (i) consists of brakes fitted to all wheels of the vehicle; and (ii) has at least 2 separate methods of activation, arranged so effective braking remains on at least 2 wheels if a method fails; or (b) 2 independent brakes, each of which, when in operation, acts directly on at least half the number of wheels of the vehicle. (3) The braking system of a motor vehicle mentioned in subrule (2) that was built after 1945 must have a service brake operating on all wheels that, when applied— (a) acts directly on the wheels and not through the vehicle's transmission; or (b) acts on a shaft between a differential of the vehicle and a wheel. (4) The braking system of a motor vehicle with 4 or more wheels must have a parking brake that— (a) is held in the applied position by direct mechanical action without the intervention of an electrical, hydraulic or pneumatic device; and (b) is fitted with a locking device that can hold the brake in the applied position; and (c) has its own separate control. (5) The parking brake may also be the emergency brake. (6) If 2 or more independent brakes are fitted to a motor vehicle with 4 or more wheels, the brakes must be arranged so brakes are applied to all the wheels on at least 1 axle of the vehicle when any brake is operated. (7) A motor bike or motor trike must be fitted with— (a) 2 independent brakes; or (b) a single brake that acts directly on all wheels of the vehicle and is arranged so effective braking remains on at least 1 wheel if a part of the system fails. (8) Subrule (7) applies to a motor bike with a sidecar attached as if the sidecar were not attached. (9) A motor trike must have a parking brake that is held in the applied position by mechanical means. 124—Operation of brakes on motor vehicles The braking system on a motor vehicle must be arranged to allow the driver of the motor vehicle to apply the brakes from a normal driving position. 125—Air or vacuum brakes on motor vehicles (1) If a motor vehicle has air brakes, the braking system of the vehicle must include at least 1 air storage tank. (2) If a motor vehicle has vacuum brakes, the braking system of the vehicle must include at least 1 vacuum storage tank. (3) An air or vacuum storage tank must be built so the service brake can be applied to meet the performance standards of rule 122 at least twice if the engine of the vehicle stops or the source of air or vacuum fails. (4) An air or vacuum storage system must be safeguarded by a check valve or other device against loss of air or vacuum if the supply fails or leaks. Division 3—Trailer braking systems 126—What brakes a trailer must have (1) A trailer with a GTM over 750 kilograms must have brakes that operate on at least 1 wheel at each end of 1 or more axles of the trailer. (2) A semi‑trailer or converter dolly with a GTM over 2 tonnes must have brakes that operate on all its wheels. 127—Operation of brakes on trailers (1) The braking system of a trailer with a GTM over 2 tonnes must allow the driver of a motor vehicle towing the trailer to operate the brakes from a normal driving position. (2) The brakes on a trailer with a GTM over 2 tonnes must— (a) operate automatically and quickly if the trailer breaks away from the towing vehicle; and (b) remain in operation for at least 15 minutes after a break-away; and (c) be able to hold the trailer on a 12% grade while in operation after a break-away. 128—Air or vacuum brakes on trailers (1) If a trailer has air brakes, its braking system must include at least 1 air storage tank. (2) If a trailer has vacuum brakes, its braking system must include at least 1 vacuum storage tank. (3) An air or vacuum storage system must— (a) be built to give a visible or audible warning to the driver of the towing vehicle, while in a normal driving position, of a lack of air or vacuum that would prevent the brakes from meeting the performance standards of rule 122; and (b) be safeguarded by a check valve or other device against loss of air or vacuum if the supply fails or leaks. (4) Subrules (1), (2) and (3) do not apply to a trailer with a GTM of 2 tonnes or less.