Grease-lubrication of roller bearings in railway waggons. Part 2: laboratory tests and selection of proper test methods

New, undestroyed greases of the same brands as those used in a field test, described in Part 1, were examined using conventional methods, such as the SKF VZF test, the roll stability test (ASTM D-1831), the Grease Worker (ASTM D-217), the torque test (ASTM 1478-91), bleeding measurements ( IP 121), yield stress measurements, the 4-ball test (ASTM D 2266-86), base oil viscosity measurements, thickener content and the cone penetration test (ASTM D217-88). The greases have also been tested with several new test methods developed at the University. A specification for relevant testing methods was drawn up and the connections between the tested parameters were investigated. It was found that the mechanical stability could be predicted with a combination of ASTM D-1831 and the limiting shear stress coefficient gamma. This coefficient is capable of predicting wear. It was found that the bearing temperature could be predicted by using the base oil viscosity.