Methods of controllling hydraulic motors

A drill head assembly, comprising:

• a modular base assembly;
• a drive shaft;
• a plurality of motor assemblies including at least a first motor and a second motor, wherein each of the first and second motors are coupled to and configured to rotate the drive shaft;
• and
• a hydraulic control system configured to selectively drive the first motor and the to rotate the drive shaft, the hydraulic control system including a pump operatively associated with the first motor, a first coupling valve operatively associated with the second motor, first parallel valves operatively associated with the second motor, and a first switching valve operatively associated with the first coupling valve and the first parallel valves, the first switching valve being configured to switch the first coupling valve between a first coupling state and a second coupling state opposite the first coupling state and to switch the first parallel valves between a first parallel state and a second parallel state opposite the first parallel state, the first parallel state being opposite the first coupling state, wherein while the first parallel valves are in the first parallel state a portion of the output of the first motor drives the second motor and while the first parallel valves are in the second parallel state a portion of the output of the pump drives the second motor.