Patent ID: 8672581

Claim:
A road construction machine, comprising: a machine frame having a frame plane and having a direction of travel; a plurality of ground engaging supports; a plurality of height adjustment devices connected between the ground engaging supports and the machine frame; and a levelling system configured to measure a distance from the frame plane to a reference location on the ground surface and to send control signals to the height adjustment devices to adjust the distance from the frame plane to the reference location on the ground surface, the levelling system including: a transmitter configured to emit at least one measuring beam representative of a reference plane; a receiver configured to detect a position of the at least one measuring beam representative of the reference plane; one of the transmitter and the receiver being rigidly connected to the machine frame; and the other of the transmitter and the receiver being connected to the machine frame so that said other of the transmitter and receiver is movable parallel to and synchronously with the machine frame along the reference location on the ground surface and so that a current distance from the frame plane to the reference location is measurable from the detected position of the at least one measuring beam representative of the reference plane.