A known type of brake system includes a motor driven hydraulic actuator in the hydraulic circuit of the brake.  The motor driven hydraulic actuator converts rotational output from the motor into linear movement of the hydraulic piston that moves reciprocally, within a piston cylinder, responsive to output rotation of the motor to provide a desired control of the hydraulic fluid pressure in the hydraulic brake system.  Such modulators are used in anti-lock brake systems, traction control systems and/or brake-by-wire systems.