Lube-Tech
solvent. The test fluid used for flushing the system was then drained and discarded. Notice that several flushes may be required to completely remove all traces of the cleaning solvent. If solvent is detected in the recirculation system, then the system should be flushed again.
Table 1. Experimental parameters for the Falex MultiSpecimen vane pump setup
Possible test parameters are summarised in Table 1. During each test the temperature, load and speed were accurately controlled, and the measurement of temperatures of oil and test surfaces, as well as frictional torque were continuously monitored and recorded. In order to establish a correlation between Vane pump tests and the cyclic-stress vane-on-flat test, we performed ISO 20763 Conestoga Vickers vane pump tests on a number of hydraulic fluids. The test setup along a schematic of the pump assembly are given in Figure 3. The testing parameters for the Conestoga Vickers vane pump tests are given in Table 2. The wear loss of both the ring and vanes was evaluated by weight loss measurements in an electrobalance.
After tests on both systems, the wear mechanisms are compared by scanning
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PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.114 page 3
electron microscope (SEM), and the testing parameters of the Falex Multispecimen system were adjusted until the same wear mechanisms were obtained.
Fig 3. (b) components and assembly of Conestoga Vickers vane pump
Table 2. Experimental parameters for ISO 20763 vane pump tests
Fig 3. (a) Conestoga Vickers vane pump tester
Advantages of this prescreening method This methodology allows for in-situ monitoring of the evolution of friction and temperature near the contacting surfaces. When the hydraulic fluid fails, and a change in wear mechanism takes place, this can be identified during the test by the sharp increase of coefficient of friction Figure 4a. The test can thus be stopped and time can be saved. In contrast, the Conestoga vane pump method only gives a wear rate at the end of test, and thus a pass/fail result without further information on the time of failure. The prescreening method furthermore allows for different hydraulic fluids to be compared in terms of frictional performance and evolution Figure 4b.
LUBE MAGAZINE NO.143 FEBRUARY 2018
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