Abstract: A supplemental steering system is provided for a machine having first and second brakes actuable for slowing rotation of first and second drive outputs or wheels, a brake actuator, and a main or primary steering system. The brake actuator is connected with a first port and a second port of a supplemental steering control valve having a first chamber and a second chamber. The first port communicates with the first chamber and the second port communicates with the second chamber. The supplemental steering control valve further includes a piston located in the bore connected to a steering input and having a neutral position generally equidistant between the first and second chambers. First and second brake ports respectively communicate the first and second chambers with the first brake.