Strength and Durability Testing for Automotive Hydraulic Brake Components
This recommended practice will specify a standard duty cycle and set of conditions for component-level durability testing. The "duty cycle" refers to a set of loading conditions (e.g. torque or pressure and cycling count), and the 'test conditions" refers to environmental conditions such as temperature, humidity, and part conditioning from prior exposure (e.g. heat aging).
Rationale:The globalization of vehicle architectures and platforms demands a global basis for testing methods and standards. The trend towards vehicles which meet performance requirements in different regions, benefits from a Recommended Practice (RP) which organizes multiple test methods for hydraulic components. This organization is critical to the success of the vehicle program, including the overall quality, reliability, cost-effectiveness, and safety of the vehicle.
To remain competitive and relevant, the development of hydraulic brake components needs to relate to vehicle usage. This correspondence or correlation ensures product design, performance, and overall durability and reliability are a flow down from vehicle-level conditions and relate to an expected vehicle or component life or warranty period. To enable the translation of vehicle-level load collectives to component-level pressure and torque levels, a flowchart is provided as a guidance to conduct such conversion and calculations. To assist test programs without vehicle- or application-specific parameters, this RP provides vehicle weights, dimensions, and brake system parameters for several vehicles covering classes A-to-H from the U.S. Code of Federal Regulation (CFR), Part 565.
The task force would like to give special recognition to the work conducted in Europe regarding load collectives and the corresponding statistical treatment. This work was made available as a direct contribution from several Original Equipment (OE) and tier-1 brake suppliers to this RP. In addition, the work and experience of task force members and their companies provides sufficient evidence to support the minimum cycles indicated as performance requirements. These requirements are already used by multiple vehicle manufacturers and brake suppliers as part of their test plans on multiple production programs. When testing in accordance to this RP, product service life is predicted to be 300000 km for regular street usage of a 99th percentile driver.
NOTE: This RP also includes a companion spreadsheet with summaries of international standards for performance and durability of hydraulic components.