On the Case of Kovalevskaya and New Examples of Integrable Conservative Systems on $S^2$

There is a well-known example of an integrable conservative system on $S^2$, the case of Kovalevskaya in the dynamics of a rigid body, possessing an integral of fourth degree in momenta. The aim of this paper is to construct new families of examples of conservative systems on $S^2$ possessing an integral of fourth degree in momenta.