Browse Publications Technical Papers 2008-01-1439

Development of Test Procedure for Validation of Power Steering Pump Metallic Pulleys 2008-01-1439

In today's automotive scenario, though Electric power steering system(EPS) is gaining importance,Hydraulic Power steering system is still a common feature in almost all passenger cars in many of the developing countries, basically because of the cost and non-availability of advanced technologies. Power steering pump is heart of entire hydraulic power steering system. Failure of the pump and/or its related sub-assemblies is a threat to the safety of the entire vehicle and its occupants during various maneuvering events on the road.
Power steering pump is coupled to the vehicle engine with its drive derived from the engine in a number of ways. However, the most common method employed by many of the OEMs is a pulley drive. Many test methods are established and followed for validation of power steering pump pulleys. However, for metallic pulleys, very meager published literature is available on the test methods for design validation.
The objective of this paper is to document the various testing procedures developed for validation of power steering Pump metallic Pulleys based on correlation with warranty field failures. Stringent performance, strength & durability test requirements are derived from the field failed samples based on failure modes observed and expected life coverage.
This paper presents a detailed description of problems faced on in-production power steering pump metallic pulleys and test procedures developed for reproduction of the warranty failures & validation of new proposals. Using FEA, the existing pulleys were examined for the failure modes and based on the analysis results new proposals of pulley design were suggested. New & improved performance, strength & durability test procedures were developed and the existing pulleys were tested to reproduce the field failures.
Based on the test procedures developed, the life of the modified power steering pump metallic pulley was examined and the best design was recommended. During the above process, various changes in the metallurgical processes were also recommended. Also, statistical methods were used to predict the B10 life of the pulleys based on the test results collected from various test procedures.


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