QC/T 237-2022Bench test methods for the performance of automobile parking brakes (English PDF)

3.1 Initial brake temperature

The temperature of parking brake disc (drum) or brake lining (friction lining) when braking is applied.

Note: The initial braking temperature is expressed in degrees Celsius.

3.2 Brake input point

The joint between the force applying mechanism on the parking brake test bench and the parking brake operating mechanism.

3.3 Brake input

The input - acted on the brake input point - used for adjusting the output force.

3.4 Integral type A

The brake - mounted in the wheel brake - that shares the same brake lining assembly as the service brake.

3.5 Integral type B

The brake - mounted in the wheel brake - that uses a special brake lining assembly.

3.6 Center type

The brake that is mounted on the transmission output shaft or transmission shaft.

4.1 Requirements for test equipment

4.1.1 The test equipment is an inertial brake test bench, whose performance indicators shall meet the test requirements of this document.

4.1.2 The brake input device of the test bench shall meet the brake input requirements of various test conditions and keep stable.

4.1.3 The brake cooling device of the test equipment shall be able to make the wind speed at the brake under test reach 11 m/s, and cover the entire brake assembly.

4.1.4 For the brake input, the relative error of measurement shall not exceed ±1%, and the relative error of control shall not exceed ±3%; for parameters such as the braking torque and the spindle speed of the test bench, the relative error of measurement shall not exceed ±1%, and the relative error of control shall not exceed ±2%. The devices and thermocouples for measuring the temperature of brake discs (drums) and brake linings shall comply with the relevant regulations in QC/T 556; the relative error of its measurement shall not exceed ±3°C, and the relative error of the moment of inertia (including the inertia of the rotating part of the test bench) shall not exceed ±5%.

4.1.5 The accuracy grade of other instruments and meters for indicating and recording various parameters shall not be lower than 1.5.

4.2 Other requirements

4.2.1 Unless otherwise specified, the final braking speed of all tests is zero.

4.2.2 Unless otherwise specified, during the test, the cooling wind speed is 11 m/s, the cooling vehicle speed is 10 km/h, and the cooling air temperature is room temperature.

6.2 The first static performance test

6.2.1 Carry out the test in the forward and backward directions of the vehicle, respectively. The test speed shall not be higher than 40 r/min, and shall keep the spindle speed as stable as possible.

6.2.2 The initial brake temperature shall not be higher than 60 °C.

6.2.3 Use the constant input method to conduct the test; adjust the brake input, and take no less than 5 points for braking within the deceleration range of 0 m/s2 ~ 2.5 m/s2; the deceleration intervals output by each braking point shall be as equal as possible, and shall increase sequentially from low to high.

6.2.4 Record the brake disc (drum) speed, temperature, brake time, brake input and output braking torque during each braking process.

6.3 The first dynamic performance test

6.3.1 Carry out the test in the forward direction of the vehicle, and the initial brake speed is 30 km/h; for the parking brake with emergency braking function, one test speed shall be added according to the following requirements:

a) M1 vehicles: the initial brake speed is 100 km/h;

b) M2 and M2 vehicles: the initial brake speed is 60 km/h;

c) N1 vehicles: the initial brake speed is 70 km/h;

d) N2 vehicles: the initial brake speed is 50 km/h;

e) N3 vehicles: the initial brake speed is 40 km/h.

6.3.2 The initial brake temperature is 80 °C ± 2 °C. When the initial brake temperature cannot be reached, raise the temperature according to the running-in test conditions.

6.3.3 Use the constant input method to conduct the test; adjust the brake input; take at least 5 points in the deceleration range of 0 m/s2 ~ 2.0 m/s2 or 0 m/s2 ~ 3.0 m/s2 (only used for the test of increasing the test speed of the parking brake with emergency braking function) for braking. The deceleration intervals output by each braking point shall be as equal as possible, and shall increase sequentially from low to high.