Harvesting machine having an obstacle sensing device

A harvesting machine with a front-mounted harvesting attachment that is pivotable about a shaft running transversely to the direction of travel and capable of lifting when an obstacle is detected comprising:

• an overpressure valve;
• a control valve;
• an electrical circuit including a sensing device and electrical signal lines connected to the overpressure valve and the control valve;
• at least one double-acting hydraulic piston and cylinder unit, having a first cylinder chamber and a second cylinder chamber, arranged on the harvesting attachment;
• an accumulator located between the first cylinder chamber and the control valve and in fluid communication therewith;
• and
• a hydraulic fluid storage tank operatively connected to the hydraulic piston and cylinder unit;
• and
• wherein the control valve is associated with the sensing device in such a way that:
• when the sensing device is not operated, the first cylinder chamber is in fluid communication with the second cylinder chamber by the control valve;
• and
• when the sensing device is operated, fluid communication between the first cylinder chamber and the second cylinder chamber is interrupted by the control valve and the second cylinder chamber is in fluid communication with the storage tank.