Development of a gear oil for Shinkansen vehicles with improved low temperature fluidity

Abstract

A gear oil with improved low-temperature fluidity has been developed for Shinkansen vehicles used in cold districts. In this gear oil, much lower low-temperature viscosity and a higher viscosity index than the current gear oil have been achieved by using highly refined mineral oils as a base oil, and newly adding viscosity index improver additives. It has been indicated from performance tests that the gear oil developed has oxidation stability and lubricating performance equal to or higher than those of the current gear oil. The gear oil developed shows enough fluidity at -30°C in bench rotation test, and enough durability performance in on-track verification tests on Shinkansen vehicles. It has also been confirmed from rotational test of small tapered roller bearing that rise in temperature of the gear oil developed is lower than the current gear oil.