GB 12676-1999 Structure, performance and test methods of automobile braking system
Some standard content:
GB12676--1999
This standard is a revision of GB/T12676--1999 "Road test method for automobile brake performance" based on international standards and regulations such as Regulation No. 13 of the United Nations Economic Commission for Europe (ECE) "Uniform provisions for brakes of motor vehicles of categories M, N and O", ISO7634-1995 "Test methods for air brake systems of towed vehicles", ISO7635-1991 "Test methods for air pressure and air-hydraulic brake performance of road vehicles" and ISO6597-1991 "Test methods for performance of hydraulic brake systems of road vehicles". After the revision, this standard is implemented as a mandatory standard. The contents of this standard on the structure and performance of automobile brake systems are technically equivalent to those of Regulation No. 13 of the United Nations Economic Commission for Europe (ECE), and the contents on the test methods for performance of automobile brake systems are technically equivalent to those of ISO6597-1991, ISO7634-1995 and ISO7635-1991. The three international standards are formulated in accordance with the requirements of ECE Regulation No. 13. This standard is a revision of GB/T12676-90. The technical content is much more than the original standard. The requirements for the structure, function and performance indicators of the automobile brake system are added, and the test method is also greatly modified. 1 From the date of implementation of this standard, the following clauses will be implemented 12 months later: ① Article 4.1.5 The requirement that the pneumatic joint connected to the trailer must be double-line or multi-line. ② Article 5.1.4 The requirement that the braking performance must be under the condition that the wheels are not locked. 2 From the date of implementation of this standard, the following clauses will be implemented 24 months later. ① Article 4.1.4.3 The requirement that the trailer air brake system and the tractor parking brake system act simultaneously. ② Article 4.2.5.1 The requirement that when a component in the energy transmission device fails, it must ensure that energy is continuously supplied to other parts that are not affected by the failure.
③ Article 4.2.12.1 The requirement for the liquid level alarm device. ④ Article 4.2.12.2 on the requirement that a failure alarm device must be installed for hydraulic brake systems. ③ Article 4.2.12.3 on the requirement for marking the type of brake fluid. Article 4.2.13 on the requirement for installing an alarm device in the energy storage device. ③ Article 4.4 on the requirement for spring brake systems. Article 5.1.5 on the requirement that the vehicle condition should comply with the requirements of Appendix A. Article 5.2.1.2 on the performance requirements for the Type 0 test with engine engagement. @ Articles 5.2.4 and 5.2.5 on the requirements for the Type I and Type IA tests of the service brake system. 3 The following clauses shall be implemented 48 months after the implementation of this standard: ① Requirements on the structure and performance of the emergency brake system (Articles 4.1.4.2, 4.2.2.5, 4.2.2.6a, 4.2.2.6b, 4.2.5.2, requirements on the alarm pressure in Article 4.2.13, Article 4.2.15, 5.2.6, 5.5). ② Requirements on the structure and performance of the trailer brake system (Articles 4.3.10, 5.3, but 5.3.4, 5.4.4). 4.2.11.1 and 4.3.8.1 require that the wear of the service brake should be able to be automatically adjusted. ④ 4.2.20 and 4.3.13 require that vehicles must be equipped with anti-lock brake devices. ③ Article 4.2.18, Article 4.3.12, Article 5.4.2.3. ③ Article 4.1.3 on the requirement that the brake lining does not contain asbestos. ? Article 5.2.7.6 on the requirement for dynamic test of parking brake system. 4 From the date of implementation of this standard, for Nz-type air brake vehicles, the above-mentioned Articles 1 and 2 are implemented 48 months later, and for N1 and N2-type hydraulic brake vehicles, Article 5.1.5 is implemented 48 months later. From the date of implementation of this standard, GB/T12676--90 is replaced at the same time. Appendix A, Appendix B and Appendix C of this standard are all appendices of the standard. This standard is proposed by the State Machinery Industry Bureau. 277
GB12676-1999
This standard is under the jurisdiction of the National Automobile Standardization Technical Committee. Drafting units of this standard: China Automotive Technology Research Center, Changchun Automobile Research Institute, Dongfeng Motor Corporation Technology Center, Chongqing Automobile Research Institute, Beijing Jeep Automobile Co., Ltd., Shenyang Jinbei Automobile Co., Ltd. The main drafters of this standard are: Liu Zuomin, Liu Yanrong, Shen Yanxing, Xu Kefang, Tang Yuejin, Zhu Bobi, Ding Zongnan. 278
1 Scope
National Standard of the People's Republic of China
Automobile Braking System
Structure, Performance and Test Methods
Road vehicle---Braking systems--Structure, performance and test methods This standard specifies the structure, performance and test methods of automobile braking systems. This standard applies to the braking systems of M and N category vehicles and O category trailers. GB 12676-1999
Replaces GB/T12676-90
This standard does not apply to vehicles with a maximum design speed of less than 25km/h and trailers connected thereto, nor to vehicles driven by disabled people.
2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest version of the following standards. GB13594-1992 Performance requirements and test methods for automobile anti-lock braking systems GB/T14168-1993 Graphical symbols for automobile brake fluid categories GB/T5922-1986 Pressure test connector for automobile and trailer pneumatic brake devices 3 Terminology
3.1 Vehicle model certification
Refers to vehicle model certification from the perspective of brake devices. 3.2 Vehicle type
refers to a type of vehicle that does not differ in the following main aspects: 3.2.1 Automobile
a) vehicle type;
b) maximum total mass;
c) mass distribution between axles,
d) maximum design speed;
e) braking device (special consideration should be given to whether the trailer has braking device); f) number and arrangement of axles;
g) engine type;
h) number of transmission gears and speed ratio;
i) drive axle speed ratio,
j) tire size.
3.2.2 Trailer
Approved by the State Administration of Quality and Technical Supervision on January 8, 1999 and implemented on October 1, 1999
a) Vehicle type
b) Maximum total mass;
c) Mass distribution between axles;
d) Braking device;
e) Number and arrangement of axles;
f) Tire size.
3.3 Braking device of the same type
refers to braking devices that are identical in the following main aspects: a) Component characteristic parameters;
b) Component type and size;
c) Component combination method.
3.4 Hydraulic brake system with energy storage device
GB 12676—1999
refers to a brake system in which the energy is provided by the pressure oil stored in one or more energy storage devices. The pressure oil is supplied by one or more hydraulic pumps with pressure limiting devices. The pressure limit of the pressure limiting device is specified by the manufacturer. 3.5 Spring brake system
refers to a brake system in which the energy required for braking is provided by one or more springs that act as energy storage devices. 3.6 Spring compression chamber
refers to a pressure chamber that produces the pressure change required to compress the spring. 3.7 Factory-specified pressure
Pressure specified by the manufacturer. Under this pressure, the vehicle should be able to achieve the specified driving braking efficiency and meet the requirements of the energy storage device and the energy supply device.
3.8 Controllable braking
The driver can increase or decrease the braking force by operating the device. The braking force and the control force are single-valued functions, and the braking force control has sufficient accuracy.
3.9 Mid-axle trailer
refers to a towed vehicle equipped with a hitch that cannot move vertically relative to the trailer, with the axle (single or multiple) placed close to the center of gravity of the trailer (when evenly loaded). The axle position should be determined to ensure that only a small vertical load, not exceeding 10% of the maximum total mass of the trailer and 10,000N (the smaller of the two), is transmitted to the towing vehicle. 4 Structural requirements for the braking system
4.1 General
4.1.1 The braking device must ensure that the vehicle meets the requirements of this standard under normal use conditions, regardless of the type of vibration it is subjected to. 4.1.2 The braking device must ensure that it has the ability to resist corrosion and aging in a normal use environment. 4.1.3 The brake lining should not contain asbestos.
4.1.4 Functions that the braking device must have
4.1.4.1 Service Brake
Regardless of the speed, load, or whether the vehicle is going uphill or downhill, the service brake system must be able to control the vehicle's movement and stop the vehicle safely, quickly and effectively; the service brake must be controllable and must ensure that the driver can brake without taking his hands off the steering wheel.
4.1.4.2 Emergency Brake
The emergency brake must stop the vehicle within a suitable distance if only one part of the service brake fails; the emergency brake must be controllable and must ensure that the driver can brake with at least one hand on the steering wheel. 4.1.4.3 Parking Brake
GB 12676—1999
The parking brake must be able to lock the working parts through purely mechanical means to stop the vehicle on an uphill or downhill slope, even when the driver leaves. The driver must be able to implement the parking brake from his seat. The parking brake of a trailer shall comply with the provisions of 4.3.10. The pneumatic brake system of the trailer and the parking brake system of the tractor may be operated simultaneously, provided that the driver can at any time check that sufficient braking performance is obtained by the purely mechanical action of the parking brake system of the tractor. 4.1.5 Pneumatic connection between the tractor and its trailer For pneumatic brake systems, the pneumatic connector to the trailer must be of two-line or multi-line type. In either case, the provisions of this standard must be met using only two lines. Non-automatically actuated disconnect devices are not permitted. For a tractor-trailer combination, the hose belongs to the tractor; for other types of trains, the hose belongs to the trailer. 4.2 Braking systems for vehicles of categories M and N
4.2.1 The braking system of the vehicle must meet the requirements specified for the service braking system, the emergency braking system and the parking braking system. 4.2.2 The braking system of the vehicle, the emergency braking system and the parking braking system may share components provided that the following requirements are met. 4.2.2.1 There shall be at least two sets of independent controls that are easily accessible to the driver from his normal driving position. Except for vehicles of categories M2 and M:, the brake control devices (except retarders) of other types of vehicles shall be designed to enable them to return to their full position when the brakes are released. The control devices of the parking brake system (or the parking brake control part of the combined control device) that are locked in the braking position by mechanical devices do not need to meet this requirement.
4.2.2.2 The control devices of the service brake system must be independent of the control devices of the parking brake system. 4.2.2.3 When the service brake system and the emergency brake system share the same control device, the efficiency of the connection between the control device and the various components of the energy transmission device shall not tend to weaken after a certain period of use. 4.2.2.4 When the service brake system and the emergency brake system share the same control device, the parking brake system must ensure that the vehicle can brake even when it is in the driving state.
When an auxiliary control device is used to at least partially brake the service brake system, it is not necessary to meet the requirements of this article. 4.2.2.5 Except for the brakes and the parts specified in 4.2.2.7, in the event of any component rupture or other failure of the service brake system (such as malfunction, partial or complete leakage of stored energy), the emergency brake system or the part of the service brake system not affected by the failure must be able to stop the vehicle according to the requirements of emergency braking.
4.2.2.6 When the service brake system and the emergency brake system share the same control device and the same energy transmission device: a) The service brake system is operated by the driver's physical strength and assisted by one or more energy storage devices. Even when the assistance fails, the driver's physical strength and the energy not affected by the failure can still ensure the implementation of emergency braking, and the force acting on the control device shall not exceed the specified maximum value.
b) If the driving braking force and energy transmission are provided only by the energy storage device controlled by the driver, there must be at least two completely independent energy storage devices, each of which must have an independent energy transmission device, and should act on the brakes of two or more wheels. The selection should enable the vehicle to achieve the specified emergency braking performance and not affect the stability of the vehicle during braking. In addition, each energy storage device must be equipped with the warning device specified in Article 4.2.13. 4.2.2.7 Certain parts, such as the brake pedal and its bracket, the brake master cylinder and its piston, the brake master valve, the brake master cylinder and pedal, the brake air chamber, the wheel cylinder and its piston and the connecting rods between the brake arm and the camshaft assembly should be regarded as parts that are not prone to failure. These parts should be large enough, easy to access for maintenance, and should have at least the same safety characteristics as other important parts of the vehicle (such as the steering linkage). If the failure of these parts will cause the vehicle to fail to achieve the specified emergency braking performance, these parts must be made of metal materials or materials with equivalent performance to metal materials, and no obvious deformation should occur during the normal operation of the braking device. 4.2.3 When the control devices of the service brake system and the emergency brake system are independent of each other, when both brake systems are working normally or one of them is not working properly, the operation of the two control devices at the same time should not make the service brake and the emergency brake inoperative. 4.2.4 When the service brake system energy transmission device fails partially, the operation of the service brake system control device should still be able to brake a sufficient number of wheels. The selection of these wheels must ensure that the residual braking efficiency of the service brake is not less than the requirements of 5.2.2. If the service brake energy transmission device of the semi-trailer is independent of the service brake energy transmission device of the tractor, the above requirements do not apply to the semi-trailer tractor.
GB12676-1999
4.2.5 When using energy other than the driver's physical strength, only one energy source (such as hydraulic pump, air compressor, etc.) may be used, but the driving device of the energy source must be safe and reliable.
4.2.5.1 When any energy transmission component of the brake system fails, it must be ensured that energy continues to be supplied to other parts not affected by the failure, so that the braking efficiency is not less than the specified emergency braking or (and) residual braking efficiency. This requirement must be ensured by a device or automatic device that is easy to operate when the vehicle is stationary.
4.2.5.2 When the energy device (such as hydraulic pump, air compressor, etc.) fails, the energy storage device located in the circuit after the device, under the conditions specified in 6.17.1.1, after the service brake system has been braked four times with full stroke, it can still stop the vehicle with the specified emergency braking efficiency when the fifth brake is applied.
4.2.5.3 For a hydraulic brake system with an energy storage device, if it meets the requirements of 5.5.3 of this standard, it is considered that the brake system has met the above requirements. 4.2.6 In order to meet the requirements in 4.2.2, 4.2.4, and 4.2.5, an automatic device that can detect its failure under normal circumstances should be used. 4.2.7 The service brake must act on all wheels of the vehicle. 4.2.8 The braking force of the service brake must be reasonably distributed between the axles. For vehicles with more than two axles, in order to avoid wheel locking or brake lining wear, when the load on certain axles of the vehicle is greatly reduced, the braking force on these axles is allowed to automatically reduce to zero, provided that the vehicle meets the performance requirements specified in Chapter 5.
4.2.9 The braking force of the service brake must be distributed symmetrically between the left and right wheels of the same axle with respect to the longitudinal center plane of the vehicle. 4.2.10 The service brake system and the parking brake system must act on braking surfaces that are permanently connected to the wheels by parts of sufficient strength. No braking surface shall be disengaged from the wheel. However, for the service brake system and the emergency brake system, the braking surface may be disengaged temporarily, such as when changing gears, after which the service brake system and the emergency brake system continue to achieve the specified effectiveness. For the parking brake system, if it is controlled only by the driver at the seat by a device that does not act by bleeding, the braking surface may be disengaged. 4.2.11 After the brake is worn, the brake clearance must be easily compensated by manual or automatic adjustment devices. Its control and energy transmission devices and brake components must have a certain reserve travel. If necessary, appropriate compensation devices should also be provided. When the brake is heated or the brake lining (block) reaches a certain degree of wear, the braking effect can still be guaranteed without the need to adjust the brake clearance immediately. 4.2.11.1 The wear of the service brake should be automatically adjusted. However, for the brakes of N2 and N, category non-road vehicles and the rear brakes of M1 and N1 category vehicles, it is not mandatory to install an automatic adjustment device. After the brake is cooled from the heat, the wear automatic adjustment device can still ensure effective braking performance, especially that the vehicle can still drive normally after the 5.23I type test and 5.24I type test. 4.2.11.2 The wear of the service brake lining (block) should be easy to check from the outside or bottom of the vehicle, and only the tools or equipment commonly used on the vehicle (such as appropriate inspection holes or some other measures) should be used during the inspection. Alternatively, an acoustic or optical warning device may be installed to alert the driver in the cab when the lining (block) needs to be replaced. For M and Ni vehicles, it is permitted to remove the front and/or rear wheels when replacing the lining (block).
4.2.12 Hydraulic brake system
4.2.12.1 The filling port of the reservoir must be easily accessible. The design and structure of the reservoir must ensure that the liquid level can be easily checked without opening the container. If this condition cannot be met, an alarm must be installed. The alarm signal light must remind the driver that a drop in the liquid level will cause the brake system to fail. The driver must be able to easily check whether the alarm is working properly. 4.2.12.2 Failure of a component of the hydraulic energy transmission device must notify the driver through a red alarm signal light, which should light up no later than the actuation control device. The signal light should remain lit as long as the failure continues and the ignition switch is in the on (running) position. However, it is also allowed to use a red signal light that lights up when the liquid level in the reservoir drops below the value specified by the manufacturer. The alarm signal light should be conspicuous even in daytime. The driver can easily check whether the warning signal light is working properly from his seat. The failure of the device shall not cause the brake system to completely lose its braking efficiency.
4.2.12.3 In the hydraulic brake system, a mark indicating the type of brake fluid used and in accordance with the provisions of GB/T14168 shall be fixed on a conspicuous position within 100mm from the reservoir filling port. The mark shall comply with the provisions of GB/T14168 and the writing shall not be easy to erase. The manufacturer may also indicate other relevant content.
4.2.13 If the service brake system that uses stored energy to operate cannot achieve the specified emergency braking performance without using the energy of the energy storage device, in addition to installing a pressure gauge, an alarm device must also be installed. When the energy stored in any part of the system drops to a certain value, the alarm device should be able to send out a light signal or an acoustic signal. At this time, regardless of the load of the vehicle, when the service brake energy storage device is no longer re-supplied with energy, the service brake system should be able to achieve the specified emergency braking efficiency when it is braked for the fifth time after four full-stroke brakings (the service brake energy transmission device should be free of faults at this time, and the clearances of each brake should be adjusted to the minimum clearance). The alarm device must be directly and permanently connected to the circuit. When the engine is running normally and the brake system is free of faults, the alarm device should not send out a signal except during the period when the energy storage device needs to be charged after the engine is started.
4.2.13.1 For vehicles that meet the requirements of 5.5.3 and are therefore considered to meet the requirements of 4.2.5.1, their alarm devices should have acoustic signals in addition to light signals. If both the optical signal and the acoustic signal device can meet the above requirements, and the acoustic signal does not work before the optical signal, it is not necessary to require the two signal devices to work at the same time.
4.2.13.2 When the hand brake is used and/or the gear shift device of the automatic transmission (selected by the manufacturer) is in the "parking" position, the acoustic signal device may not work.
4.2.14 Without violating the provisions of 4.1.4.3, if the operation of the braking system must use auxiliary energy, the energy storage device must ensure that: even if the engine is turned off or the auxiliary energy supply drive device fails, the vehicle still has sufficient braking efficiency to enable it to stop according to the specified requirements.
If the parking brake device is operated by the driver's physical strength and assisted by a power-assisting device, it must be ensured that the parking brake can be applied even if the power-assisting device fails. If necessary, an energy storage device independent of the normal energy supply to the power-assisting device can be used. This energy storage device can also be the energy storage device of the service brake system.
4.2.15 For vehicles that are allowed to be coupled with trailers and whose brakes are controlled by the driver of the tractor, the service brake system of the tractor must be equipped with a device with the following functions: when the trailer brake system fails or the air supply pipeline (or other possible connection method) between the tractor and the trailer is broken, the tractor can still brake with the specified emergency braking effect. This device must be installed on the tractor. 4.2.16 Energy can only be supplied to the auxiliary equipment when the specified deceleration can still be achieved during the operation of the auxiliary equipment, or when the energy source is damaged, the operation of the auxiliary equipment does not cause the stored energy of the brake device to drop below the specified value in 4.2.13. 4.2.17 For trailers of categories 03 and O., their service brake system must be continuous braking or semi-continuous braking. 4.2.18 The braking system of tractors used to tow O. and O. trailers must meet the following requirements: 4.2.18.1 When the emergency brake system of the tractor is in effect, the trailer must also have controllable braking. 4.2.18.2 The service brake system of the tractor shall consist of at least two independent circuits. In the event of failure of the service brake system of the tractor, the circuit not affected by the failure shall enable partial or full controllable braking of the trailer brakes. If a valve which is not normally operative is used to apply such braking, it shall only be used if the driver can check the proper function of the valve from the cab or outside the vehicle without any tools.
4.2.18.3 In the event of a break or leak in one of the air supply line connections (or other possible connections), the driver shall be able to apply the trailer brakes in whole or in part using the service brake, emergency brake or parking brake control, unless such a break or leak would automatically brake the trailer with the braking effect specified in 5.3.5. 4.2.18.4 For dual-line air pressure systems, the requirements of 4.2.18.3 may be considered to be met if the following conditions are met: a) After the control device specified in 4.2.18.3 is fully actuated, the pressure in the air supply line must drop to 0.15 MPa within 2 seconds. b) When the air supply line is exhausted at a rate of at least 0.1 MPa/s, the trailer automatic brake must start to work before the air supply line pressure drops to 0.2 MPa.
4.2.19 For vehicles that are allowed to be coupled with a Class O: or Class 04 trailer, the service brake system of the trailer is only allowed to be operated in conjunction with the service brake system, emergency brake system or parking brake system of the tractor. 4.2.20 For M3 tourist buses with a maximum gross mass greater than 12,000 kg and N: vehicles with a maximum gross mass greater than 16,000 kg that are allowed to be coupled with a Class 04 trailer, a Class I anti-lock brake device that complies with the provisions of GB13594 must be installed. 4.30 Braking devices for trailers of category O1
4.3.101 trailers do not need to be equipped with a service brake system. If a service brake system is installed for a trailer of category O1, it shall meet the requirements of a trailer of category O2. 4.3.202 trailers must be equipped with a service brake system, which may be continuous, semi-continuous or inertia type, but inertia service brake systems are not allowed to be used for semi-trailers.
GB 12676—1999
4.3.30: and category O4 trailers must be equipped with a continuous or semi-continuous service brake system. 4.3.4 The service brake system must act on all wheels of the trailer. 4.3.5 The braking force of the service brake system must be reasonably distributed between the axles. 4.3.6 The braking force of each brake system must be distributed symmetrically between the left and right wheels of the same axle relative to the longitudinal center plane of the vehicle. 4.3.7 The braking surface required to achieve the specified braking efficiency must remain permanently connected to the wheel. The connection may be rigid or connected by components that are not prone to failure.
4.3.8 Brake wear must be compensated by manual or automatic adjustment devices. The brake control device and energy transmission device as well as the brake components must have a certain reserve travel. If necessary, there should also be appropriate compensation devices to ensure that the braking efficiency can be guaranteed without immediate adjustment of the brake clearance when the brake heats up or the brake lining reaches a certain degree of wear. 4.3.8.1 The wear of the service brake should be automatically adjusted. For trailers of categories O1 and O2, an automatic adjustment device may be installed as an option. After the brake cools down from the heat, the automatic wear adjustment device can still ensure effective braking, in particular, the vehicle can still drive normally after type 1 test and type I test in accordance with the requirements of 5.2.3 and 5.2.4. 4.3.8.2 The wear of the service brake lining should be easy to check from the outside or bottom of the vehicle, and only the tools or equipment commonly used on the vehicle (such as appropriate inspection holes or other measures) should be used during the inspection. 4.3.9 The brake system must ensure that the trailer stops automatically if the hitch is disengaged during driving. This provision does not apply to trailers with a total mass of less than 1.5 tonnes and equipped with auxiliary hitch devices (such as chains, wire ropes, etc.) in addition to the main hitch, which can prevent the drawbar from touching the ground and allow the trailer to have some residual steering ability when the main hitch is disengaged. 4.3.10 For trailers equipped with service brakes, the trailer must be able to produce parking brakes if the trailer is separated from the towing vehicle. The parking brake must be able to be actuated by a person standing on the ground, but if the trailer is a passenger trailer, the parking brake must be able to be actuated inside the trailer. 4.3.11 If the trailer is equipped with a device that can cut off the air pressure to the trailer brake (not the parking brake), this device must be returned to the air supply position before resuming the air supply to the trailer. 4.3.12 Class 0: and 04 trailers equipped with dual-circuit air brake systems shall comply with the provisions of 4.2.18.4. 4.3.13O.Class trailers must be equipped with anti-lock brakes that meet the requirements of GB13594. 4.4 Spring brake system
4.4.1 The spring brake system shall not be used as a service brake system. When the service brake system energy transmission device partially fails, the spring brake system is allowed to be used to enable the vehicle to meet the residual braking performance requirements of 5.2.2. The spring brake must be a controllable brake. Except for the semi-trailer tractor specified in 4.2.4 of this standard, the spring brake device of other vehicles shall not be used as the only residual brake device. Vacuum spring brake systems shall not be used for trailers. 4.4.2 Slight pressure changes in the energy supply circuit of the spring compression chamber shall not cause significant changes in the braking force. 4.4.3 The energy supply circuit of the spring compression chamber must be equipped with a separate dedicated energy accumulator or there must be at least two independent energy accumulators to supply energy to it. The trailer brake air supply line may be connected to the above supply circuit, but it must be ensured that the pressure drop in the trailer air supply line does not produce the braking effect of the spring. The auxiliary equipment is only allowed to obtain energy from the air supply circuit of the spring brake actuator. However, when the auxiliary device is working, even in the case of energy failure, the stored energy for the spring brake actuator will not drop below the level that can release the spring brake once. For tractors, during the period of recharging the brake system from zero pressure, the spring brake shall not be released before the pressure of the service brake system reaches a pressure value sufficient to ensure that the fully loaded vehicle at least reaches the specified emergency braking performance. This requirement does not apply to trailers.
4.4.4 For tractors, when the initial pressure in the spring compression chamber is equal to the maximum design pressure, the spring brake system must be able to brake and release the brake at least 3 times.
For trailers, it must be ensured that after the trailer is disconnected from its tractor (the pressure in the air supply line before disconnection is 0.65MPa), the brake can still be released at least 3 times. This condition should be met when the brake clearance is adjusted as small as possible. In addition, when the trailer is coupled to the tractor, it must be possible to apply and release the parking brake device that meets the requirements of 4.3.10. 4.4.5 For tractors, the pressure in the spring compression chamber corresponding to the time when the spring starts to apply the brake (with its clearance adjusted as small as possible) shall not be higher than 80% of its minimum working pressure. For trailers, the above pressure in the spring compression chamber shall not be higher than the pressure of the service brake system after four full-stroke braking according to the provisions of 5.5.4. The initial pressure is adjusted to 0.65MPa. 284
GB 12676-1999
4.4.6 When the pressure in the energy supply pipeline of the spring compression chamber (excluding the pipeline of the auxiliary brake release device) drops to the point where the brake components begin to move, the light or sound signal alarm device shall start to work. Under the condition that this requirement is met, the alarm device that meets the provisions of 4.2.13 is allowed to be used. This article does not apply to trailers.
4.4.7 For tractors that are allowed to couple trailers with continuous or semi-continuous braking systems and are equipped with spring braking systems, the automatic braking of the spring braking system should be able to cause the braking of the trailer. 4.4.8 In the event of failure of the spring braking device, it should be ensured that the brakes can be released. This requirement can be achieved through an auxiliary device. The energy accumulator of the auxiliary release device using stored energy should be independent of the energy accumulator of the spring braking device. 4.4.9 If the operation of the auxiliary device in 4.4.8 requires the use of a tool, this tool should be provided as a vehicle-mounted tool. 5 Braking system performance requirements
5.1 General
5.1.1 The braking system performance specified in this standard is determined under specified conditions by measuring the braking distance at the corresponding initial speed and/or the fully developed average deceleration.
The fully exerted mean deceleration (MFDD) is calculated according to the following formula:—
MFDD = 25. 92(3.= s,) m/s*
Wherein: \—test vehicle braking initial speed, km/h; b—0.8 test vehicle speed, km/h;
V——0.1 test vehicle speed, km/h,
S—the distance traveled from the test vehicle speed to b, m; S. ——the distance traveled from the test vehicle speed to ve, m. 5.1.2 The braking distance refers to the distance traveled by the vehicle from the time the driver starts to actuate the brake control device to the time the vehicle stops. The initial braking speed refers to the vehicle speed when the driver starts to actuate the brake control device. During the test, the initial braking speed should not be less than 98% of the specified value. 5.1.3 When testing any vehicle, the road test shall be carried out under the following conditions to measure its braking performance: 5.1.3.1 The load state of the test vehicle must comply with the regulations for various tests and shall be stated in the test report. 5.1.3.2 All tests must be carried out at the specified speed. If the maximum speed specified by the vehicle manufacturer is lower than the speed specified in the test, the test may be carried out at the maximum speed of the vehicle.
5.1.4 The braking performance specified in this standard must be obtained under the conditions that the wheels are not locked, no part deviates from the 3.7m channel width and there is no abnormal vibration. When the vehicle speed is lower than 15km/h, the wheels are allowed to lock. The maximum control force shall not exceed the specified value. 5.1.5 When various vehicles brake on the road surface with gradually decreasing adhesion coefficient, the vehicle condition shall comply with the provisions of Appendix A (Appendix of the standard). 5.1.6 The requirements for test site, climatic conditions, vehicle condition, measurement accuracy, test procedures, etc. shall comply with the provisions of Chapter 6. 5.2 Braking performance of M and N category vehicles
5.2.1 Performance requirements for service brake system type 0 test 5.2.1.1 Performance requirements for engine disconnected type 0 test Empty and fully loaded test vehicles shall be conducted in accordance with the test methods specified in 6.6.2.1a) and 6.6.2.2a) respectively. At the specified vehicle speed, the test results of each type of vehicle must meet the minimum performance requirements specified in Table 1. Table 1
Vehicle type
Test vehicle initial braking speed, km/h
Braking distance Smax, m
Vehicle type
Fully exerted average deceleration MFDDmin
Maximum control force, N
GB12676--1999
Table 1 (end)
5.2.1.2 Engine-engaged Type 0 test performance requirements M
a) Empty and fully loaded test vehicles shall be tested in accordance with the method specified in 6.6, and the initial braking speed of the test vehicle shall be 30% and 80% of the factory-specified maximum speed respectively; for vehicles with speed limiting devices, the maximum speed shall be the speed specified by the speed limiting device. The best performance parameters that can be achieved shall be measured during the test, and the vehicle driving status shall be recorded. For semi-trailer tractors that are artificially loaded to simulate the impact of a fully loaded semi-trailer on the tractor, the test speed shall not exceed 80km/h. b) Empty and fully loaded test vehicles shall be subject to additional tests in accordance with the methods specified in 6.6.2.1c) and 6.6.2.2c). The initial speed of the test shall not exceed the speed of the vehicle of the type specified in Table 2. All types of vehicles must meet the minimum performance requirements specified in Table 2. For semi-trailer tractors that are artificially loaded to simulate the impact of a fully loaded semi-trailer on the tractor, the test speed shall not exceed 80 km/h. 5.2.2 Residual braking performance after failure of the energy transmission device of the service brake If a component of the energy transmission device of the service brake system fails, it shall be tested in accordance with the method specified in 6.8.5. The initial braking speed and residual braking performance of the test vehicle shall meet the requirements of Table 3. The control force applied during the test shall not exceed 700 N. Table 2
Vehicle type
Test vehicle initial braking speed√=80%
Umax, but
Braking distance Smax
Fully exerted average deceleration MFDDaio
Maximum control force, N
Test vehicle braking
Vehicle type
Initial braking speed
u,km/h
Fully loaded braking distance Smax
Fully exerted
Average deceleration
MFDD,m/s 2
Unloaded braking distance Smx
Fully exerted
Average deceleration
5.2.3 Braking performance of service brake system type 1 test GB12676--1999
5.2.3.1 After a fully loaded vehicle has been subjected to the service brake system type I test in accordance with 6.9, the hot performance of the service brake system shall be measured within 60 seconds immediately. The test conditions (control force is kept constant and shall not be greater than the average value of the control force used in the type 0 test, and the temperature may be different) are the same as those of the type 0 test with the engine disconnected. The measured hot brake performance shall not be less than 80% of the specified value for the vehicle of this type, nor less than 60% of the performance actually measured in the type 0 test with the engine disconnected. 5.2.3.2 For vehicles that meet 60% of the requirements specified in 5.2.3.1 but do not meet 80% of the requirements specified in 5.2.3.1, the hot brake performance test may be conducted again with a control force not exceeding that specified in 5.2.1.1, and the results of the two tests shall be recorded. 5.2.4 Braking system Type 1 test Braking performance
This braking performance is only applicable to vehicles of category M: and N. 5.2.4.1 The energy input to a fully loaded vehicle must be equivalent to the energy of driving 6 km downhill on a 6% slope at an average speed of 30 km/h (the transmission is in an appropriate gear; vehicles equipped with a retarder can use the retarder) in the same time. The use of the transmission gear must ensure that the engine speed does not exceed the maximum value specified by the manufacturer. 5.2.4.2 For vehicles whose energy is absorbed only by engine braking, the average speed is allowed to have a deviation of ±5 km/h. The transmission gear should be such that the vehicle's speed is stable at close to 30 km/h when going down a 6% slope. If the deceleration measurement is used to determine the braking effectiveness of engine braking only, the measured average deceleration should not be less than 0.5m/s2. 5.2.4.3 After the Type I test is carried out in accordance with 6.11, the hot braking performance of the service brake device should be measured within 60s. The test conditions are the same as those of the Type 0 test with the engine disengaged (the temperature may be different). The hot braking performance is shown in Table 4, and the control force does not exceed 700N: Table 4
Vehicle type
5.2.5 Braking system Type 1A test braking performance
Braking distance Smax
0.15+1:33m
0. 15 +1 33
Fully exerted average deceleration MFDDmia
This braking performance is only applicable to Class M buses among non-city buses with a total mass greater than 10,000kg, and such vehicles are not subject to the Type I test in 5.2.4.
5.2.5.1 The energy input to the fully loaded vehicle is equivalent to the energy of driving 6 km downhill on a 7% slope at an average speed of 30 km/h in the same time. During the test, the service brake, emergency brake and parking brake shall not be used. The gearbox gear shall be such that the engine speed shall not exceed the maximum speed specified by the factory.
For vehicles equipped with an integral retarder, the integral retarder is allowed to be used if the retarder can act with appropriate phase to make the service brake ineffective. This situation can be determined by checking whether the brake is in a cold state. 5.2.5.2 For vehicles whose energy is absorbed only by engine braking, a deviation of ± 5 km/h is allowed for the average speed. The gearbox gear shall be such that the vehicle's speed is stable at nearly 30 km/h when descending a 7% slope. If the deceleration measurement is used to determine the effectiveness of the engine braking alone, the measured average deceleration shall not be less than 0.6 m/s°. 5.2.6 Performance requirements of emergency brake system
The braking performance of the emergency brake system shall be tested by a Type 0 test with the engine disconnected. The initial test speed and performance requirements are shown in Table 5. The test shall be conducted in accordance with the provisions of 6.8.
Test vehicle
Initial braking speed
GB126761999
Braking distance Smax
Fully exerted
Average deceleration MFDDl
5.2.7 Performance requirements of parking brake system
The parking brake system must enable a fully loaded vehicle to stop on an 18% slope (uphill or downhill). 5.2.7.1
Manual control
Control force max, N
For vehicles with trailers, the parking brake system of the tractor must be able to stop the train on a 12% slope. Foot control
The parking brake is hand-controlled, and its control force: M1 vehicles shall not exceed 400N, and other vehicles shall not exceed 600N. The parking brake is foot-controlled, and its control force: M1 vehicles shall not exceed 500N, and other vehicles shall not exceed 700N. 5.2.7.4
5.2.7.5 Several activations of the parking brake system are allowed before the specified performance is achieved. 5.2.7.6 In order to check the requirements specified in 4.2.2.4 of this standard, a fully loaded vehicle shall be tested at the test speed specified in 5.2.6 in accordance with the type 0 test method with the engine disengaged, and the parking brake control device or the auxiliary control device of the service brake shall be operated so that the average deceleration fully exerted and the instantaneous deceleration before stopping shall not be less than 1.5m/s\, and the control force shall not exceed the specified value. As long as the specified requirements are achieved once in the test, it is considered to meet the requirements. For the parking brake of M, or N1 type vehicles that do not share the brake lining with the service brake, it is allowed to be tested at an initial speed of 60km/h according to the manufacturer's requirements. The fully developed average deceleration shall not be less than 2.0m/s, and the instantaneous average deceleration before the vehicle stops shall not be less than 1.5m/s.
5.3 Braking performance of O type trailers
5.3.10 Type test performance requirements
If the trailer service brake system is continuous or semi-continuous, the sum of the braking forces acting on the periphery of the braked wheels shall not be less than X% of the sum of the static loads of each wheel when the vehicle is at its maximum mass. The value of X is as follows: full trailer, center axle trailer, when fully loaded and unloaded: X=50; semi-trailer, when fully loaded and unloaded: X=45. If the trailer is equipped with a pneumatic brake system, during the test, the test vehicle speed is 60km/h, the control line pressure does not exceed 0.65MPa, and the intake line pressure does not exceed 0.7MPa. In addition, fully loaded trailers are required to undergo an additional test at a speed of 40 km/h in order to compare the results with those of the Type I test.
5.3.20 Type 1 test performance requirements for trailers of category 0
After the Type I test in Article 6.10, the hot braking performance of the service brake system shall be measured immediately within 60 seconds. The initial braking speed of the test vehicle is 40 km/h. The hot braking force on the wheel rim shall not be less than 36% of the static wheel load of the trailer at the maximum mass state, nor less than 60% of the value recorded in the Type 0 test at the same speed. If it does not reach 60% of the value recorded in the Type 0 test, the test is considered invalid. If the hot braking force does not reach 36% of the static wheel load of the trailer at the maximum mass state, the test may be repeated. During the test, the control line pressure may be different from that of the additional test, but shall not exceed 0.65 MPa. 5.3.3 Type I test performance requirements for O4 trailers: After a fully loaded trailer has been subjected to Type I test in 6.13, the hot braking performance of the service brake system shall be measured within 60 seconds. The initial braking speed of the test vehicle shall be 40 km/h. The hot braking force on the wheel rim shall not be less than 288 of the total static load of the wheels of the trailer at its maximum mass.8.
Test vehicle
Initial speed
GB126761999
Braking distance Smax
Fully exerted
Average deceleration MFDDl
5.2.7 Parking brake system performance requirements
The parking brake system must enable a fully loaded vehicle to stop on an 18% slope (uphill or downhill). 5.2.7.1
Hand control
Control force max, N
For vehicles with trailers, the parking brake system of the tractor must be able to stop the train on a 12% slope. Foot control
The parking brake is manually controlled, and its control force: M, Class vehicles shall not exceed 400N, and other classes of vehicles shall not exceed 600N. The parking brake is foot-controlled, and its control force shall not exceed 500N for M1 vehicles and 700N for other vehicles. 5.2.7.4
5.2.7.5 It is allowed to activate the parking brake system several times before the specified performance is achieved. 5.2.7.6 In order to check the requirements specified in 4.2.2.4 of this standard, the fully loaded vehicle shall be tested at the test speed specified in 5.2.6 in accordance with the type 0 test method with the engine disengaged, and the parking brake control device or the auxiliary control device of the service brake shall be operated so that the average deceleration fully exerted and the instantaneous deceleration before stopping shall not be less than 1.5m/s\, and the control force shall not exceed the specified value. As long as the specified requirements are achieved once during the test, it is considered to meet the requirements. For the parking brake of M, or N1 type vehicles that do not share the brake lining with the service brake, it is allowed to be tested at an initial speed of 60km/h according to the manufacturer's requirements. The fully developed average deceleration shall not be less than 2.0m/s, and the instantaneous average deceleration before the vehicle stops shall not be less than 1.5m/s.
5.3 Braking performance of O type trailers
5.3.10 Type test performance requirements
If the trailer service brake system is continuous or semi-continuous, the sum of the braking forces acting on the periphery of the braked wheels shall not be less than X% of the sum of the static loads of each wheel when the vehicle is at its maximum mass. The value of X is as follows: full trailer, center axle trailer, when fully loaded and unloaded: X=50; semi-trailer, when fully loaded and unloaded: X=45. If the trailer is equipped with a pneumatic brake system, during the test, the test vehicle speed is 60km/h, the control line pressure does not exceed 0.65MPa, and the intake line pressure does not exceed 0.7MPa. In addition, fully loaded trailers are required to undergo an additional test at a speed of 40 km/h in order to compare the results with those of the Type I test.
5.3.20 Type 1 test performance requirements for trailers of category 0
After the Type I test in Article 6.10, the hot braking performance of the service brake system shall be measured immediately within 60 seconds. The initial braking speed of the test vehicle is 40 km/h. The hot braking force on the wheel rim shall not be less than 36% of the static wheel load of the trailer at the maximum mass state, nor less than 60% of the value recorded in the Type 0 test at the same speed. If it does not reach 60% of the value recorded in the Type 0 test, the test is considered invalid. If the hot braking force does not reach 36% of the static wheel load of the trailer at the maximum mass state, the test may be repeated. During the test, the control line pressure may be different from that of the additional test, but shall not exceed 0.65 MPa. 5.3.3 Type I test performance requirements for O4 trailers: After a fully loaded trailer has been subjected to Type I test in 6.13, the hot braking performance of the service brake system shall be measured within 60 seconds. The initial braking speed of the test vehicle shall be 40 km/h. The hot braking force on the wheel rim shall not be less than 288 of the total static load of the wheels of the trailer at its maximum mass.8.
Test vehicle
Initial speed
GB126761999
Braking distance Smax
Fully exerted
Average deceleration MFDDl
5.2.7 Parking brake system performance requirements
The parking brake system must enable a fully loaded vehicle to stop on an 18% slope (uphill or downhill). 5.2.7.1
Hand control
Control force max, N
For vehicles with trailers, the parking brake system of the tractor must be able to stop the train on a 12% slope. Foot control
The parking brake is manually controlled, and its control force: M, Class vehicles shall not exceed 400N, and other classes of vehicles shall not exceed 600N. The parking brake is foot-controlled, and its control force shall not exceed 500N for M1 vehicles and 700N for other vehicles. 5.2.7.4
5.2.7.5 It is allowed to activate the parking brake system several times before the specified performance is achieved. 5.2.7.6 In order to check the requirements specified in 4.2.2.4 of this standard, the fully loaded vehicle shall be tested at the test speed specified in 5.2.6 in accordance with the type 0 test method with the engine disengaged, and the parking brake control device or the auxiliary control device of the service brake shall be operated so that the average deceleration fully exerted and the instantaneous deceleration before stopping shall not be less than 1.5m/s\, and the control force shall not exceed the specified value. As long as the specified requirements are achieved once during the test, it is considered to meet the requirements. For the parking brake of M, or N1 type vehicles that do not share the brake lining with the service brake, it is allowed to be tested at an initial speed of 60km/h according to the manufacturer's requirements. The fully developed average deceleration shall not be less than 2.0m/s, and the instantaneous average deceleration before the vehicle stops shall not be less than 1.5m/s.
5.3 Braking performance of O type trailers
5.3.10 Type test performance requirementsbZxz.net
If the trailer service brake system is continuous or semi-continuous, the sum of the braking forces acting on the periphery of the braked wheels shall not be less than X% of the sum of the static loads of each wheel when the vehicle is at its maximum mass. The value of X is as follows: full trailer, center axle trailer, when fully loaded and unloaded: X=50; semi-trailer, when fully loaded and unloaded: X=45. If the trailer is equipped with a pneumatic brake system, during the test, the test vehicle speed is 60km/h, the control line pressure does not exceed 0.65MPa, and the intake line pressure does not exceed 0.7MPa. In addition, fully loaded trailers are required to undergo an additional test at a speed of 40 km/h in order to compare the results with those of the Type I test.
5.3.20 Type 1 test performance requirements for trailers of category 0
After the Type I test in Article 6.10, the hot braking performance of the service brake system shall be measured immediately within 60 seconds. The initial braking speed of the test vehicle is 40 km/h. The hot braking force on the wheel rim shall not be less than 36% of the static wheel load of the trailer at the maximum mass state, nor less than 60% of the value recorded in the Type 0 test at the same speed. If it does not reach 60% of the value recorded in the Type 0 test, the test is considered invalid. If the hot braking force does not reach 36% of the static wheel load of the trailer at the maximum mass state, the test may be repeated. During the test, the control line pressure may be different from that of the additional test, but shall not exceed 0.65 MPa. 5.3.3 Type I test performance requirements for O4 trailers: After a fully loaded trailer has been subjected to Type I test in 6.13, the hot braking performance of the service brake system shall be measured within 60 seconds. The initial braking speed of the test vehicle shall be 40 km/h. The hot braking force on the wheel rim shall not be less than 288 of the total static load of the wheels of the trailer at its maximum mass.
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