During 1967-1970, the operation of wide- and narrow-capture harvesters was studied at Norilsk mines. During the tests, the average and instantaneous values of power consumption P, current I, feed rate v_n and feed force F_п were measured. Special sensors and recording equipment were made to record these parameters. One of the tasks of the tests was to establish the dependence of the harvester productivity on the extracted power of the formation.