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Air spring systems are increasingly used on suspensions for commercial vehicles. To prove their durability a reliable test procedure is necessary: to be applied already in the development stage to be used to qualify individual air spring manufacturers and to assure manufacturing quality. In this paper the test procedure, the test facility and some test results are presented. In the test facility the air spring is mounted on a fixture and is loaded by a servohydraulic actuator. The mounting of the air spring allows to simulate all operational deformations, being decisive for the durability. Based on the extensive measurements on proving ground and public roads the test program was worked out. The test program includes besides the loading and deformations during driving also kneeling operations as well as high and low temperatures. The accelerated laboratory tests deliver results which correspond to the existing experience at the service usage.

In this paper the criteria and the requirements for the approval of the service strength and the durability of vital car suspension components are treated. The overview of the main influences on the fatigue life is given and the methodology for the design evaluation and a reliable time and cost saving development, including durability approval, are described. These include: Description of representative, customer related loading Procedure for design evaluation based on customer usage Corresponding test programs for durability approval including the requirements for statistical validation and quality assurance of manufacturing. On two examples - a wheel and a suspension arm - the procedure including individual steps is explained.