Adjustable string line sensors for slip form paving

A method of controlling a slip form paving machine, the machine including:

• a machine frame having a front end and a rear end;
• a plurality of ground engaging wheels or tracks;
• front and rear height adjustable lifting columns supporting the machine frame from the ground engaging wheels or tracks, the lifting columns being adjustable to adjust a longitudinal inclination of the paving machine frame in a paving direction;
• a slip form mold supported from the machine frame for molding a mass of concrete into a formed not yet hardened concrete slab as the paving machine moves forward in the paving direction;
• a front stringline sensor;
• a front sensor actuator arranged to adjust a vertical position of the front stringline sensor relative to the machine frame;
• a rear stringline sensor;
• and
• a rear sensor actuator arranged to adjust a vertical position of the rear stringline sensor relative to the machine frame;
• the method comprising:
• (a) determining with a controller a desired change in the longitudinal inclination of the machine frame;
• and
• (b) sending a command signal from the controller to one or more of the sensor actuators and thereby adjusting the vertical position of one or more of the stringline sensors to effect the desired change in longitudinal inclination.