Crossed helical gears have an important position in power transmission. Important advantages of the crossed helical gears are the small design, the realization of high ratios in one stage, and the low noise characteristics. The paper presents a theoretical and experimental research of mesh efficiency, tooth friction coefficient and wear for a wheel of crossed helical gears made of Fe1.5Cr0.2Mo sintered steel with sinter-hardening treatment and without additional treatment. The calculation method is also given for the determination of wear load capacity of the worm with a helical gear made of Fe1.5Cr0.2Mo sintered steel with sinter-hardening treatment. These results provide product developers with the first important clues for indicators for calculation of the worm with a helical gear.