To solve this problem, we must first determine the internal torques ${\mathrm{T}}_1$ and ${\mathrm{T}}_2$ acting in the shafts. To do this, we must account for the effect of the differing gear sizes.

Once ${\mathrm{T}}_1$ and ${\mathrm{T}}_2$ are known, the shear stresses ${\mathrm{\tau }}_1$ and ${\mathrm{\tau }}_2$ can be calculated.