<p><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">The article considers the object of belt transmission driving all the drums of the USK cotton<span style="font-size:11.0pt"><span style="font-family:"Calibri",sans-serif">[1]</span></span>cleaning unit, most commonly used in the cleaning shop of cotton-cleaning plants, and theoretically calculates the improved design of belt transmission consisting of two pulleys and a belt. Traction power of belt and belt transmission according to experimental methods is characterized by dependence of belt relative slip and efficiency on transmission resistance coefficient. A mathematical model of new belt transmission design has been developed, which allows theoretical estimating of belt tensile strength and rational operating mode in elastic slipping zone; the design has been installed at the machinery of the cotton-cleaning plant, a part of unitary enterprise “Real Agro Cotton”. The results of the experiment were analyzed.</span></span></p>