A milling machine includes a main frame, a rotatable cutter drum coupled with the frame, and an engine mounted to the frame and operatively connected with the drum, and crawler assemblies connected with the frame and including a hydraulic motor. A pump is disposed on the frame for driving the crawler motor and is adjustable to vary a speed of the motor. A regulator adjusts cutter drum speed, a speed selector generates an input corresponding to a desired drum speed, and a sensor senses a drum speed. A control receives input from the selector and the sensor and operates the regulator such that drum speed corresponds to the desired speed. Further, the control also compares sensed drum speed with desired drum speed and adjusts the pump to reduce crawler motor speed when the sensed drum speed has a value lesser than a predetermined portion of the desired drum speed.