Application Examples

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Prescreening the ISO20763 & ASTM D7043 Vickers Vane Pump tests

WHY ? : the standard method for evaluating anti-wear of hydraulic fluids in a vane pump, is by the 100 hour ASTM or 250 hour ISO method, using a real Conestoga-built vane pump.  This method takes a long time to run, and requires a lot of fluid.  This makes it difficult to use the method for development or research.

Various lab or bench test methods have been evaluted as a prescreening method, but none of them have shown any satisfactory correlation with real pump wear, so far (as clearly proven by the review of G.E. Totten 1996, Prediction of Hydraulic Fluid Performance: Bench Test Modeling, Dr: George E. Totten, Union Carbide Corp. Roland J. Bishop, Jr., Union Carbide Corp. Gary H. Kling, Caterpillar Inc. Presented at the International Fluid Power Exposition@ and Technical Conference 23-25 April 1996).  Recent attempts to correlate an SRV based test have also failed the correlation test.

HOW ? : We have studied the wear mechanism that takes place in a vane pump, and with the help of some special test specimens - designed for the Falex Multispecimen machine - recreated the vane contact vs. ring conditions, and the pressure pulses created by the inlet and outlet ports.  By using these custom specimens and a recirculating oil system, we can run a wear test with similar test conditions, in 22 to 44 hours.  By careful experimental design, we can run the test without creating excessive heat or catastrophic failure, so we focus on simulating the normal working conditions of a vane pump.

 

 b2ap3_thumbnail_Falex-Vane-specimens Applications b2ap3_thumbnail_WorkingLimits Applications b2ap3_thumbnail_ComparisonWear Applications

RESULT : 

  • we can simulate the same wear mechanism as in the Vane pump test (and as in real vane pumps)
  • we can rank the wear rate of different hydraulic fluids, correlating with the wear rate ranking in the Vane pump test
  • we can monitor in situ the coefficient of friction and online wear, giving us more information about the mechanism and evolution during the test
  • we can avoid the excessive heating of the test specimens

 

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