Abstract: A gate control for thyristor converters connected in opposition to reversibly drive a D.C. electric motor in which one of the thyristor converters operates as a rectifier and the other remains still when the motor runs forward, and vice versa. The gate control includes an operational amplifier to carry out current control for the converters and to generate an output therefrom which follows the motor armature voltage during the switchover between converters to prepare for reverse rotation of the motor. The other converter, which operates momentarily as an inverter to feed electric energy from the motor back to an A.C. electric voltage supply thereof to reduce the motor speed, is controlled to enable its inverter voltage to coincide substantially with the motor armature voltage so as not to cause excessive rushing current from the motor into the inverter at the instant of the switchover.