GB/T 37336-2019Brake drum for automobile (English PDF)

3.1 Mounting spigot hole

A center hole which mates with the hub.

3.2 Mounting surface

The surface of the brake drum which fits the hub.

3.3 Limiting wear size

The maximum radial size allowed after the friction surface of brake drum is worn.

4.1 Classification of brake drum

the thermal fatigue test in accordance with A.4.1.1, shall not fail.

5.9.2 High load test

Brake drum samples, after completion of the high load test in accordance with A.4.2, shall not fail.

6.1 Mechanical properties

6.1.1 Tensile strength Samples for tensile strength shall be taken from the middle of the friction surface of brake drum. The sampling position is shown in Figure 3. If there are special requirements, it can be agreed between the supplier and the purchaser.

The testing method of tensile strength shall be in accordance with the provisions of GB/T 228.1.

Figure 3 -- Schematic diagram of sampling position of sample for tensile strength In the case where the tensile strength sampling size is limited, the wedge pressure strength can be used instead of the tensile strength. The size of the wedge sample shall comply with the requirements of Table 6. For the conversion method of wedge pressure strength and tensile strength, see Appendix D of GB/T 9439-2010. The wedge pressure strength is the average Sampling position

A.1 Scope

This appendix specifies the test related requirements, failure criteria, and test methods for the bench tests such as thermal fatigue test and high load test of brake drum.

A.2 Test related requirements

A.2.1 Moment of inertia

The actual inertia setting shall be as close as possible to the theoretical inertia.

The deviation shall be within the range of ±5% of the theoretical inertia. The theoretical inertia refers to the inertia distributed on the corresponding wheel of the total inertia generated when the vehicle is braked. It shall be calculated according to formula (A.1).

Where:

I - Moment of inertia, in kilograms of square meters (kg · m2); m - Test mass (the mass of the vehicle's maximum design total mass distributed on the corresponding wheel when braking), in kilograms (kg); r - Tire rolling radius, in meters (m).

A.2.2 Test mass

A.2.2.1 For vehicles with a maximum design total mass of less than 7500 kg, the test mass shall be calculated according to formula (A.2) or formula (A.3).

Where:

b) The hydraulic brake is 25 MPa/s±5 MPa/s.

A.2.5 Sampling rate

The sampling rate of brake line pressure and braking torque shall be greater than 20 Hz.

A.2.6 Temperature measurement

The thermocouple mounting position is at the center radius of the friction track of brake lining contact surface. The temperature measurement shall meet the requirements of QC/T 556.

A.2.7 Sample and other brake requirements

The test shall use a new brake drum and a new brake lining. The friction surface of brake drum shall be clean. Brake linings and other brake parts shall be original parts. There is no grease or other foreign matter on the brake lining surface. During the test, the brake lining, when worn to the limit, is allowed to be replaced.

A.3 Sample failure criteria

During the bench test, when one of the following phenomena occurs on the brake drum, it is determined that the brake drum sample has failed.

a) The crack length of friction surface of brake drum exceeds two-thirds of the width of the friction surface of the brake drum;

b) The crack on the friction surface of brake drum reaches the outer edge of the friction surface of brake drum;

c) The brake drum has a penetrative crack;

d) In any area outside the friction surface, there are any types of structural damage or cracks.

A.4 Test methods and test conditions

A.4.1 Thermal fatigue test

A.4.1.1 Brake drum for type M1 and N1 vehicles

The test methods and test conditions of the brake drum for type M1 and N1 vehicles are shown in Table A.3. […]