Abstract: Based on the example of crankshafts of three-plunger single-acting reciprocating pumps, analytic model for fatigue reliability of crankshaft is built by decomposing forces on it following the corresponding coordinate system, dispersing the periodic stress, and determining the computing cross-section. Data are derived by using the developed strength computation and verification software for reciprocating pump crankshaft and the fatigue reliability of crankshaft model is analyzed in detail by using the radius vector method. By the method, the fatigue reliability of a series of failed crankshafts and those with good actual use effect is computed and analyzed and reasonable value for fatigue reliability of crankshaft of three-plunger single-acting reciprocating pump is obtained. And the max plunger force that crankshaft can work safely and reliably is also calculated and applied to some crankshafts with too high original reliability, which make full use of the surplus capacity of the original reciprocating pump unit. Fatigue reliability analysis of reciprocating pump crankshaft has significant theoretical and practical application value.

Key words: Crankshaft, Fatigue limit, Fatigue reliability, Reciprocating pump, Reliability