In mechanical engineering, screw drives are widely used, which convert rotational motion into translational motion. These include roller drives (RD), which have high performance characteristics and are by far the most promising. For the production of RD, special expensive imported machines are required, therefore, in Russia, as part of the import substitution program, nut-free RDs have been developed, the manufacture of which is possible on universal equipment. They are chosen as the object of research. For reliable, durable and economical operation of nut-free RDs, their reliable calculations are required according to the most important performance criteria. In this case, first, a force calculation of the transmission is performed, then its details, connections of details and transmission as a whole mechanism are calculated for strength, rigidity, durability, etc. The article considers the force calculation of nut-free RD, which have a number of features, including the feature of loading its intermediate parts - threaded rollers. A force from the actuator acts on the roller along its axial line, and roller is balanced by axial forces on the thread of the roller interacting with the thread of the screw. From here, the overturning moment from axial forces acts on the roller, which is balanced by the redistribution of forces on the thread of the roller and the forces from the two rings that keep the roller from radial movement. This leads to uneven distribution of the load between the thread turns of the roller, which is estimated by the coefficient of uneven loading. The article reveals a design parameter that leads to a change in the coefficient of uneven loading of a nut-free RD during operation. That parameter is the position along the axis of the first thread turn from the end of the roller, which receives the load (working thread turns) from the actuator, and other working thread turns along the axis of the roller. The reason for this change is the variation in the number of working threads turns of the roller and the distance of the balancing force on the working turns. At the same time, the range of the coefficient of uneven loading of a nut-free RD is quite large and must be taken into account in the calculations.