During 1967–1970, the operation of wide- and narrow-cutting combines was studied at Norilsk mines. During the tests, the average and instantaneous values of power consumption P, current I, feed rate vₙ and feed force Fₙ were measured. Special sensors and recording equipment were manufactured to record these parameters. One of the tasks of the tests was to establish the dependence of combine productivity on the extracted thickness of the seam.