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Similar standardsGB/T 44123-2024: Test methods of hydraulic braking systems for motor vehicles---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT44123-2024GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 43.040.40 CCS T 24 Test Methods of Hydraulic Braking Systems for Motor Vehicles Issued on: MAY 28, 2024 Implemented on: SEPTEMBER 1, 2024 Issued by. State Administration for Market Regulation; Standardization Administration of the People’s Republic of China. Table of ContentsForeword... 4 1 Scope... 5 2 Normative References... 5 3 Terms and Definitions... 5 4 Test Conditions... 5 4.1 Road Conditions... 5 4.2 Environmental Conditions... 6 4.3 Test Vehicle... 6 4.4 Test Equipment... 6 5 Test Methods... 7 5.1 General Requirements... 7 5.2 Preliminary Test and Static Inspection... 10 5.3 No-load Basic Performance Test... 10 5.4 Failure Performance Test... 10 5.5 Full-load Basic Performance Test... 10 5.6 Braking and Running Deviation Tests of Vehicles Equipped with Temporary Spare wheel / tire... 10 5.7 Additional Test for Braking Systems with Auxiliary Energy... 11 5.8 Test Data Processing... 11 Appendix A (normative) Preliminary Test and Static Inspection... 12 A.1 Component Inspection... 12 A.2 Braking System Operation Inspection... 12 A.3 Alarm Signal Inspection... 12 A.4 Pipeline Pressure Relation Inspection... 13 A.5 Additional Inspection of Service Braking System with Electronic Control Transmission Device... 13 Appendix B (normative) No-load Basic Performance Test... 15 B.1 Cold State Performance (O-type) Test of Service Brakes with Power Disengaged.. 15 B.2 Cold State Performance (O-type) Test of Service Brakes with Power Engaged... 15 Appendix C (normative) Failure Performance Test... 17 C.1 General Requirements... 17 C.2 Circuit Failure Test... 17 C.3 Assistance Failure Test... 18 Test Methods of Hydraulic Braking Systems for Motor Vehicles1 ScopeThis document specifies the test conditions and test methods of hydraulic braking systems for motor vehicles. This document is applicable to Category-M and Category-N vehicles with hydraulic braking systems as specified in GB/T 15089.2 Normative ReferencesThe contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 5620 Road Vehicles - Braking of Automotive Vehicles and Their Trailers - Vocabulary GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgement of Limiting Values GB 12676 Technical Requirements and Testing Methods for Commercial Vehicle and Trailer Braking Systems GB/T 15089 Classification of Power-driven Vehicles and Trailers GB 21670 Technical Requirements and Testing Methods for Passenger Car Braking Systems3 Terms and DefinitionsThe terms and definitions defined in GB 12676, GB 21670, GB/T 5620 and GB/T 15089 are applicable to this document.4 Test Conditions4.1 Road Conditions 4.1.1 Road surface The test road surface shall be a straight, solid asphalt road surface or concrete road surface or charged to the state of charge or first charged to above the state, and then, discharged to a fixed load at a roughly constant power, until the corresponding state of charge is reached. For vehicles powered only by power batteries, the state of charge can be adjusted by driving the vehicle. For tests conducted with the power battery partially charged, it is advisable to conduct them as soon as possible after the required state of charge is reached. 5.1.10 For vehicles equipped with an electric regenerative braking system, the state requirements for the electric regenerative braking system during the O-type test depend on the type of the electric regenerative braking system. If the A-type electric regenerative braking system has a separate control device, during the O-type test, the A-type electric regenerative braking system shall not be enabled. The braking force generated by the B-type electric regenerative braking system shall not exceed the minimum level guaranteed by the system design, or the test shall be conducted without using the regenerative braking components. If the power battery is in one of the following states of charge, then, it is considered to meet the conditions. a) The maximum state of charge recommended by the manufacturer in the vehicle instruction manual; b) If the manufacturer does not provide specific recommendations, the state of charge shall not be less than 95%; c) The highest level of state of charge that can be achieved by the vehicle’s automatic control charging. 5.2 Preliminary Test and Static Inspection Preliminary test and static inspection shall be carried out in accordance with Appendix A. 5.3 No-load Basic Performance Test No-load basic performance test shall be carried out in accordance with Appendix B. 5.4 Failure Performance Test The failure performance test shall be carried out in accordance with Appendix C. 5.5 Full-load Basic Performance Test The full-load basic performance test shall be carried out in accordance with Appendix D. 5.6 Braking and Running Deviation Tests of Vehicles Equipped with Temporary Spare wheel / tire The braking and running deviation tests of Category-M1 and Category-N1 vehicles equipped with temporary spare wheel / tire shall be carried out in accordance with Appendix E.Appendix A(normative) Preliminary Test and Static Inspection A.1 Component Inspection A.1.1 Check the appearance of the braking system to confirm whether the braking system and its components are correctly connected and reliably installed, and whether there is no leakage or component interference that may affect safety. A.1.2 Perform static operation of the service brake to check whether the service brake acts on all wheels. By disassembling the pipeline, lifting and observing, etc., check and record the layout of the hydraulic circuit. A.2 Braking System Operation Inspection A.2.1 Service braking system inspection When the vehicle is stationary, and the driver wears a fixed seat belt and holds the steering wheel with both hands, check whether the service brake control device can be actuated from the driving position, and check whether the service brake and parking brake control devices are independent of each other. A.2.2 Parking brake system inspection When the vehicle is stationary, and the driver wears a fixed seat belt, check whether the parking brake control device can be actuated from the driving position. A.2.3 Emergency braking system inspection When the vehicle is stationary, and the driver wears a fixed seat belt and holds the steering wheel with at least one hand (for Category-M1 vehicles, two hands are required), check whether the emergency brake control device can be actuated at full stroke from the driving position. A.3 Alarm Signal Inspection A.3.1 For vehicles equipped with an anti-lock braking system (ABS), when the vehicle is stationary and the anti-lock braking system is powered on after the vehicle is powered on, check whether the yellow alarm signal is on and the system self-checks. If there is no fault, check whether the alarm signal is off. Check whether the alarm signal is clearly visible during the day. A.3.2 When the vehicle is stationary, by disconnecting the power supply line of the sensor, disconnecting the external line of the controller and disconnecting the regulator circuit, etc., simulate different ABS electrical faults, and check whether an optical alarm signal is issued to the driver and whether the alarm signal is clearly visible during the day. A.4 Pipeline Pressure Relation Inspection A.4.1 Relations between pipeline pressure and control force When the vehicle is stationary, install a control force measuring device and a pipeline pressure sensor on the vehicle and release the parking brake. Then, actuate the service brake control device, and slowly increase the control force from 0 to the maximum allowable value (500 N for Category-M1 vehicles and 700 N for other categories), and record the control force and pipeline pressure curve. Check in the following two states. a) Normal assistance state. 1) For vehicles that rely on the engine to provide vacuum assistance (intake manifold or mechanical vacuum pump), increase the engine speed from idle to above 50% of the rated speed, run 4 ~ 5 times, and then, carry out the test while the engine is at idle speed; 2) For vehicles with vacuum assistance or hydraulic assistance of energy storage devices, the energy level of the energy storage device shall be 90% of the manufacturer’s recommended value; 3) For vehicles with electronic assistance, the power supply voltage shall be at the manufacturer’s recommended value. b) No assistance state. A.4.2 Relations between pipeline pressure and time A.4.2.1 The initial energy level is set in accordance with A.4.1 a). A.4.2.2 When vehicle is stationary, quickly press the brake pedal. The service brake control force increases rapidly from 0 to the maximum allowable value (500 N for Category-M1 vehicles and 700 N for other categories). The pedaling process is as fast as possible, but it cannot significantly exceed the maximum allowable control force. Record the pressure growth curve of each axle / wheel. The triggering moment of the service brake control device is used as the starting point for evaluating the response time, and the pressure growth curve of the most unfavorable axle / wheel is used to determine the static response time. A.5 Additional Inspection of Service Braking System with Electronic Control Transmission Device A.5.1 When the vehicle is stationary, perform the following additional inspections on the service braking system. a) Release the parking brake, set the power device on/off control to the “ON” (“RUN”) position, actuate the service brake, and record the pipeline pressure. The control force for Category-M1 vehicles shall not exceed 500 N, and the control force for other categories shall not exceed 700 N; D.4 Type II Test D.4.1 General requirements D.4.1.1 This test is applicable to Category-M3 vehicles equipped with hydraulic (excluding air- over-hydraulic) braking systems. D.4.1.2 When the vehicle is fully loaded, the test is carried out using the method specified in D.4.2.1 or D.4.2.2.The average speed deviation shall not exceed 5 km/h. D.4.1.3 If the auxiliary braking system of the vehicle is a retarder and it cannot generate sufficient braking force due to the influence of the driving distance during the test, the acting force of the retarder can be gradually increased to maintain the specified speed. D.4.1.4 If the auxiliary braking system of the vehicle is engine braking and it cannot generate sufficient braking force, the driver of the test vehicle can assist in maintaining the specified vehicle speed by adjusting the control force of the service braking system. If the service braking system is used as assistance, after completing the ramp test / simulated ramp traction test, within 60 seconds and in accordance with the test conditions specified in Table B.1, the O-type test with power disengaged shall be carried out. D.4.2 Test methods D.4.2.1 Ramp test Only use the auxiliary braking system to brake, and continuously drive downhill at an average vehicle speed of 30 km/h on a 6% ramp for 6 km. The selected gear shall ensure that the power unit revolution speed does not exceed the maximum revolution speed specified by the vehicle manufacturer. D.4.2.2 Simulated ramp traction test Use a tractor equipped with a tension gauge and traction device to tow the vehicle for 6 km at an average vehicle speed of 30 km/h and only use the auxiliary braking system to balance the tensile force of the tractor. The braking force of the auxiliary braking system and the traction force of the tractor shall be coordinated to keep the vehicle moving at a uniform speed of 30 km/h, and the traction force shall be equivalent to 6% of the total mass of the test vehicle. In order to ensure the effectiveness of the test, the traction force shall not be less than 4% of the total mass of the test vehicle at any time. During the test, record the vehicle speed and traction force. D.5 Parking Brake System Test D.5.1 Static test D.5.1.1 Through the service brake, put a fully loaded vehicle in a stationary state on an 18% ramp (20% ramp for Category-M1 vehicles) and keep it in a downhill state. Put the transmission in neutral or N gear, apply the parking brake, record the maximum control force during the test, release the service brake, and keep it stationary for at least 5 minutes. The maximum control force applied during the test shall not exceed 600 N (for hand control device) or 700 N (for foot control device) [for Category-M1 vehicles, the control force shall not exceed 400 N (for hand control device) or 500 N (for foot control device)]. This test allows the parking brake to be operated multiple times to achieve the required parking brake holding force, but the control force of each operation shall be within the specified range. D.5.1.2 Maintain the uphill state on the ramp and test in accordance with D.5.1.1. D.5.1.3 For vehicles that are allowed to be coupled to unbraked trailers, additional tests shall be conducted using one of the following methods. a) Actual vehicle method (recommended method). the train reaches the maximum design total mass by coupling a suitable trailer, and the test is conducted on a 12% ramp in accordance with D.5.1.1 and D.5.1.2; b) Simulation method. the ramp required for the simulation test is the slope corresponding to the ratio of the maximum design total mass of the train to the main vehicle multiplied by 12%. If there is no suitable ramp, a steeper ramp close to the slope shall be selected, and the test shall be conducted in accordance with D.5.1.1 and D.5.1.2. D.5.1.4 If there is no suitable ramp to conduct the tests described in D.5.1.1 ~ D.5.1.3, the parking brake performance can be checked by traction test on a horizontal road surface to simulate the ramp parking brake. connect the front end of the vehicle to the tractor, apply the parking brake, then, start the tractor and slowly apply traction force, until the vehicle shows a tendency to move, and record the traction force. Then, connect the rear end of the vehicle to the tractor, drag the vehicle in the reverse direction for testing, and record the traction force. D.5.2 Dynamic test When the vehicle is fully loaded, at an initial test vehicle speed of 30 km/h in neutral or N gear, use the parking brake to brake once. The control force shall not exceed the limit required for the corresponding vehicle model in D.5.1.1.Record the control force, vehicle speed and braking deceleration. D.5.3 Additional test for vehicles equipped with electronic control transmission parking brake system D.5.3.1 Simulate an electrical failure of the control device, or a damage of the internal wiring (excluding the power supply line) of the electronic control transmission connecting the control device and the electronic control unit (ECU), and on an 8% up and down ramp, in accordance with D.5.1.1 and D.5.1.2, carry out the test. For vehicles with automatic parking function in stationary state, the following inspections shall also be carried out. ---When the ignition (start) switch is turned off, check whether the parking brake is still separate control device, the device shall not be used during the test. D.6.2.3 For vehicles equipped with a B-type electric regenerative braking system, if the specified vehicle speed cannot be reached within the cycle, a thermal state performance test shall be performed at the highest vehicle speed that can be achieved after the heating cycle. For comparison, Category-M1 vehicles shall also be subject to an O-type test with power disengaged at full load at the same vehicle speed after completing the recovery performance test. D.6.3 Recovery performance test D.6.3.1 Recovery process For Category-M1 vehicles, after the thermal state performance test is completely, immediately accelerate to 50 km/h in the shortest possible time, use the highest gear that is suitable for the vehicle speed, and at an average deceleration of 3 m/s2, perform service braking. After the braking, immediately accelerate to 50 km/h in the shortest possible time and maintain the vehicle speed; at a position of 1.5 km away from the starting point of the last braking, at a deceleration of 3 m/s2, brake again. Repeat this process, until the total number of braking times reaches 4 times. D.6.3.2 Recovery performance After the last braking in the recovery process is completely, immediately accelerate to the test vehicle speed specified in Table B.1 in the shortest possible time and perform the O-type test with power disengaged. The average control force used shall not exceed the control force actually used in the O-type test at full load. D.6.4 Cold state inspection Let the brakes cool to ambient temperature and check whether the brakes are binding. For vehicles equipped with automatic wear compensation devices, the hottest brakes shall be cooled down to below 100 °C, and the wheels shall be checked to see if they can freely rotate. For vehicles other than Category-M1, if any wheels cannot be manually turned due to brake resistance, measure the temperature of the brakes, then, drive the vehicle at a constant speed of 60 km/h for 1 km ~ 2 km, measure the temperature of the brakes again, and record the temperature rise of the brakes.Appendix F(normative) Additional Test for Braking Systems with Auxiliary Energy F.1 General Requirements F.1.1 In accordance with the information provided by the manufacturer, confirm the type of vehicle assistance / powered braking system. For vehicles that must use auxiliary energy to achieve emergency braking performance, in accordance with the methods in this Appendix, perform additional energy storage inspection tests. F.1.2 During the test, the parking brake must be released, and confirm that the brake clearance of all wheels is adjusted to the smallest possible size, while ensuring that the wheels can be manually turned. F.2 Vacuum Assistance System F.2.1 Vacuum extraction capability F.2.1.1 Test conditions If the vacuum source is the vacuum generated by the engine, the test shall be performed at the engine idle speed defined by the vehicle manufacturer. If the vacuum source is a vacuum pump driven by the engine, the test shall be performed at 65% of the maximum power speed of the engine. If the revolution speed of the engine is limited when the vehicle is stationary, then, the test shall be performed at 65% of the manufacturer’s limited speed. If the vacuum source is an electric vacuum pump, the test shall be performed at the rated power supply voltage specified by the vehicle manufacturer. F.2.1.2 Test method The vehicle is stationary, and the transmission is in neutral or N gear. Before starting the power unit, repeatedly step on the brake pedal, until the vacuum is zero. Then, start the power unit, and under the conditions specified in F.2.1.1, measure the time to reach the vacuum pressure specified by the manufacturer that can satisfy the vehicle’s service braking performance under full load. F.2.2 Capacity of energy storage device F.2.2.1 Test conditions The initial vacuum in the energy storage device shall comply with the vehicle manufacturer’s provisions, but it shall not exceed 90% of the maximum vacuum. The energy storage device shall not be replenished during the test, and all additional devices and associated accumulators shall be disconnected. F.2.2.2 Test method The vehicle is stationary, the transmission is in neutral or N gear, and the ignition / start switch is turned off. If an additional accumulator is installed, disconnect the connection between the additional accumulator and its energy supply equipment. If the vacuum source is a vacuum pump, fully actuate the service brake for 8 times, then, with the vacuum source disconnected, perform an emergency braking test at the initial test vehicle speed and control force specified in Table C.1, and record the initial braking speed, control force, deceleration, braking distance and vehicle stability. If the vacuum source is an engine, fully actuate the service brake for 4 times, then, with the vacuum source disconnected, perform an emergency braking test at the initial test vehicle speed and control force specified in Table C.1, and record the initial braking speed, control force, deceleration, braking distance and vehicle stability. F.2.3 Low vacuum alarm test Release system energy to the alarm vacuum threshold and check whether the alarm device emits an optical or acoustic alarm signal when the vacuum is significantly reduced. With the vacuum source disconnected, carry out 4 full braking operations. Then, in accordance with the initial test vehicle speed and control force specified in Table C.1, carry out an emergency braking test, and record the initial braking speed, control force, deceleration, braking distance and vehicle stability. F.3 Hydraulic Assistance System F.3.1 Energy supply capacity F.3.1.1 Test conditions During the test, the energy storage device of the auxiliary equipment shall not be disconnected (except for automatic disconnection). If the energy comes from the engine, the energy shall be supplied at the maximum power speed of the engine or at the speed allowed by the speed limiter (if equipped). If the energy comes from a motor-driven hydraulic pump, the test shall be carried out at the rated supply voltage specified by the vehicle manufacturer. F.3.1.2 Test method The vehicle is stationary, and the transmission is in neutral or N gear. Without replenishing shall not exceed the energy supply cut-in pressure. The energy storage device shall not be replenished during the test, and any additional devices and associated accumulators shall be disconnected. The frequency of fully actuated braking operations shall ensure that there is a time interval of at least 60 seconds between each operation, and each actuation shall be maintained for 20 s ~ 30 s. F.4.2.2 Test method The vehicle is stationary, the transmission is in neutral or N gear, and the energy supply device is disconnected. Starting from the accumulator pressure level specified by the manufacturer that does not exceed the energy supply cut-in pressure, fully actuate the service brake for 8 times. Then, at the initial speed specified in Table C.1, perform an emergency braking test, and record the initial braking speed, control force, deceleration, braking distance and vehicle stability. F.4.3 Hydraulic transmission failure F.4.3.1 General If the hydraulic braking system has only one hydraulic pump to supply energy to two accumulators, a hydraulic transmission failure test is required. If the system has two hydraulic pumps driving two completely independent circuits, when one circuit fails, the other circuit can normally work, then, this test is not required. F.4.3.2 Test method Before the test, it shall first be checked through the information provided by the manufacturer whether a leakage fault in one transmission circuit will prevent the shared hydraulic pump from supplying energy to the other circuit. At the most unfavorable position of a hydraulic transmission circuit, simulate a failure. Disconnect the auxiliary equipment and the associated accumulator and adjust the accumulator pressure to the level specified by the manufacturer, but it shall not exceed the hydraulic pump cut-in pressure. When the hydraulic pump is not in operation or the engine is idling, the following tests shall be conducted. a) If a leakage fault in one transmission circuit will prevent the shared hydraulic pump from supplying energy to the other circuit, then, fully actuate the service brake for 8 times and record the pipeline pressure at the 9th actuation; b) If a leakage fault in one transmission circuit will not prevent the shared hydraulic pump from supplying energy to the other circuit, then, fully actuate the service brake for 4 times and record the pipeline pressure at the 5th actuation. If there are multiple positions for the selection of the most unfavorable position of the simulated failure and it is impossible to accurately judge, then, each position is tested. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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