The need for instrumental measurement of the traction force of the friction drive of the vertical spindles of the cotton harvesting machineM. Shoumarova, T. Abdillayev, A.A. Duskulov and Sh.A. YusupovE3S Web of Conf., 443 (2023) 04014DOI: https://doi.org/10.1051/e3sconf/202344304014