One of the most important elements of hydraulic fracturingHydraulic fracturing equipment are pumping unitsPumping unit. Mechanical transmissionsMechanical transmission of various types and gearing are often used to transmit force from the power unit to the operating unit. One of the fundamental parts in mechanical transmissions is often the pinion shaftPinion shaft. The pinion shaft offers several advantages over the bevel gear, but it is not without its disadvantages. The alternatives for replacing the bevel gear with a pinion shaftPinion shaft are the following types of connection: keyed, splined and profile. The aim of the study is to replace the pinion shaft with a split shaft-to-sleeve type connection with justification of the choice of the type of connection. In the present work, profile joints of shaft-stub type have been analyzed. A calculation methodology for this type of profile connectionProfile connection has been created. A verification calculation for bucklingBuckling of keyed and splined joints has been performed. According to the resultsResult of the conducted research of the profile joint with an oval hole for shaft fit, the conclusions are made that the greater the range of distances within which it is possible to change the larger diameter of the oval at a given value of the maximum torque, the less the arising contact stresses and displacements in the joint. In the result of the study of replacing the pinion shaftPinion shaft with a split joint of the shaft-hub type, the diagrams of contact stresses and displacements in the keyed, splined and profile joints at a given value of maximum torque were constructed and analyzed at a given value of maximum torque.