Assessment of railway curve lubricant performance using a twin-disc tester

Grease retentivity was found to be greater with lower roughness and with more grease applied. Repeat tests with discs used for starvation tests led to very high wear rates. This was thought to arise as cracks initiated as the first run reached dry conditions were pressurised by grease reapplied in the subsequent tests causing crack growth and intersection and associated pitting and spalling. Clear differences were seen between the greases in terms of their retentivity performance although there was considerable scatter. Coefficients of traction (COT) in the early stages of the starvation tests and during the fully lubricated tests were below 0.1 and very consistent. Again differences could be found between greases under the test conditions used.