Scientists of the Rolling-Stock Research Institute under the Branch Academy of Railway Science have made sleeve bearing material of cast-steel mixed with high-purity sulfur without using copper alloy and succeeded in producing it at factories after passing the trial stage.

It is much better than copper alloy in such mechanical properties as tensile strength, extension rate and friction coefficient and is more than 1.5 times longer in serviceable life.

It is the same with copper alloy in lubrication condition and its production cost is one tenth compared to copper alloy.

The material, applicable to all kinds of crushers, disintegrators, presses, cranes, drawing machines, etc., has already been introduced in the Sunchon Cement Complex, Wonsan Rolling-Stock Complex and other units.