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We consider open star clusters (OSCs) with the proper motions, parallaxes,and line-of-sight velocities calculated by various authors from Gaia DR2 data.The distance scale factor has been found by analyzing the separate solutions ofthe basic kinematic equations to be $p=1.00\pm0.04.$ It shows that thedistances calculated using the parallaxes from the Gaia DR2 catalogue do notneed any correction factor. We have investigated the solutions obtained fromvarious OSC samples differing in both age and accuracy of their parallax andline-of-sight velocity measurements. The solution obtained from a sample of 930OSCs satisfying the constraints on the age logt<9 and the relativetrigonometric parallax error <30% is recognized to be the best one, with 384OSCs in this sample having the mean line-of-sight velocities calculated from atleast three probable members of the corresponding clusters. As a result of thesimultaneous solution of all the basic kinematic equations, we have found thefollowing kinematic parameters from this sample:$(U,V,W)_\odot=(8.53,11.22,7.83)\pm(0.38,0.46,0.32)$ km s$^{-1}$,$\Omega_0=28.71\pm0.22$ km s$^{-1}$ kpc$^{-1}$, $\Omega'_0=-4.100\pm0.058$ kms$^{-1}$ kpc$^{-2}$, and $\Omega''_0= 0.736\pm0.033$ km s$^{-1}$ kpc$^{-3}$.The linear rotation velocity at the adopted at the adopted solar distance$R_0=8\pm0.15$ kpc is $V_0=229.7\pm4.6$ km s$^{-1}$. An analysis of the propermotions for these 930 OSCs has shown that, apart from the rotation around theGalactic z axis, there is rotation of the entire sample around the x axis withan angular velocity of $0.48\pm0.15$ km s$^{-1}$ kpc$^{-1}$ differingsignificantly from zero.

Kinematic Properties of Open Star Clusters with Data from the Gaia DR2 Catalogue