FIELD: earthmoving equipment. SUBSTANCE: invention relates to earthmoving equipment and can be used in construction works. A trench rotary excavator contains a bucket rotor with a drive for its rotation, a tractor with a feed drive, a dump conveyor with a drive for moving soil carried out of the trench by a rotor, and a speed controller. The excavator is equipped with the first and second signal division units, a unit for setting the average design feed of the excavator to the bucket, the output of which is connected to the input bus of the divisible first division unit, a unit for setting the average design speed of rotation of the rotor, the output of which is connected by the input bus of the divider of the first division unit, a setpoint of the average value of the soil loosening coefficient of the trench to be developed by the excavator, a setpoint the current speed of rotation of the rotor, a ground meter installed between the tractor and the rotor, a unit for calculating the current value of the soil loosening coefficient, the input of which is connected to the output of the meter, a smoothing filter, the input of which is connected to the output of the unit for calculating the current value of the soil loosening coefficient, a three-input signal multiplication unit. In this case, the first input of the three-input signal multiplication unit is connected to the output of the first block by dividing signals, the second input is connected to the setpoint of the average value of the soil loosening coefficient, and the third input is connected to the output of the setpoint of the current rotor rotation speed. In this case, the output of the multiplication unit is connected to the input bus of the divisible of second division unit, the filter output is connected to the input bus of the divider of the second division unit. The excavator speed controller is made in the form of three autonomous control units, the input of the first of which is connected to the output of the current rotor speed setter, and the output is connected to the rotor rotation drive, the input of the second is connected to the output of the second division unit, and the output is connected to the tractor feed drive, and the third is made in the form of a programming unit connected to the drive of a dump conveyor. EFFECT: increase in the reliability of the excavator. 1 cl, 1 dwg.