The article presents the results of experimental research on the sorghum harvester, equipped with a threshing-separating device of the inertial-combing type for harvesting Donskoe-35 variety broom sorghum, work quality in the conditions of farms in the south-western zone of the Volgograd region of Russia. The heads losses change (Qm) dependences on the combine speed (Vk) were determined: before the threshing chamber Qm = – 0.079Vk
2 + 0.426Vk + 0.01, behind the header Qm = – 0.133Vk
3 + 1.2Vk
2 – 3.567Vk + 4.1 and after the threshing chamber Qm = 0.057Vk
2 – 0.321Vk + 1.046, as well as grain losses (Qz): behind the normalizer Qz = 0,03Vk
3 – 0,241Vk
2 + 0,686Vk – 0,083, by the Qz = 0,004Vk
2 + 0,025Vk + 0,28 and under-threshing in a head Qz = 0,033Vk
2 – 0,032Vk + 0,204. The sorghum harvester threshing growing heads by a threshing-separating device of an inertial-combing type showed a high quality of work: an increased level of heads losses was observed behind the header at combine speeds up to 1.5 m/s, but they did not exceed 2.6% at a combine speed of 0.5 m/s; while studying types of grain losses, the losses behind the normalizer reached the level of 0.6% at a combine speed of 3.0 m/s; the loss of grain behind the thresher and under-threshing in the head did not exceed 0.4%.