ISO 6312 pdf download.Road vehicles — Brake linings — Shear test procedure for disc brake pad and drum brake shoe assemblies
1 Scope
This International Standard specifies a method for measuring the strength of the bond connection between the lining material and the carrier in disc brake pad and drum brake shoe assemblies (shear strength). This International Standard is applicable to integrally moulded, riveted and bonded assemblies of both types of brake on road vehicles.
2 Normative reference
The following normative document contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 61 1 , Roadvehicles — Braking ofautomotive vehicles andtheirtrailers — Vocabulary.
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 61 1 and the following apply. 3.1 lining friction material component of a brake lining assembly 3.2 carrier component of a brake lining assembly to which the friction pad is attached 3.3 bond area contact area between lining and carrier 3.4 shear strength ratio of the load at failure divided by the bond area
4 Symbols and units
The symbols and preferred units used in this International Standard are given in Table 1 .
5 Sampling and conditioning
This procedure may be used on samples during product development, on finished products, or after special treatment (such as that covered by ISO 631 4) or usage. Testing may be performed on a complete assembly or section of an assembly. Sample edges may be prepared to ensure good contact with the loading and fixed tools. Shims should be removed. When testing a lined shoe, the test area may cover the full assembly or segments of an assembly confined by saw cutting down to the carrier (see Figure 1 ). Five samples should be used. NOTE The test procedure applies a load in a direction which might not be in accordance with the loading direction of the product in service. The shear behaviour could be influenced by high aspect ratio, chamfered or slotted pads.
6 Test rig and fixtures
6.1 Test rig The test rig shall be a compression or tensile testing machine or similar (shear testing) machine of sufficient capacity to apply the shearing load by activating a ram. The test rig shall be provided with equipment to register the exact load applied at the instant of shear failure. The load application rate shall be controlled in such a way that the load increases at an average rate of (4 500 ? 1 000) N/s (as determined from typical vehicle-based evaluation). If a constant crosshead speed machine is being used the load rate shall be set to (1 0 ? 1 ) mm/min. This shall be indicated in the results, which, it shall be noted, cannot be compared to tests conducted on machines of the constant load type. Shock loading shall be avoided. 6.2 Fixtures 6.2.1 General The shearing test fixture shall have the means to hold a test sample such that it is parallel to the loading tool. This tool shall have a radius of 1 ,5 mm at the part in contact with the test sample. 6.2.2 Drum brake shoe assembly The fixture (see Figure 2) shall be designed so that the loading tool is in contact with the edge of the lining for the full sample length and thickness within (1 ? 0,2) mm of the shoe platform. Load application on the loading tool shall be in a direction parallel to the plane of the shoe platform. The shoe shall be supported to maintain uniform loading along the length of the lining sample. The width of the loading tool shall be greater than the width, W, of the lining.