System and method for detecting rack fault condition of passenger boarding bridge lift columns

A method for preventing a rack fault condition of a passenger boarding bridge, the passenger boarding bridge having a first electromechanical screw jack and a second electromechanical screw jack mounted one each adjacent opposite sidewall surfaces thereof, the method comprising:

• using a plurality of electromagnetic sensors, sensing separately a rotational movement of each one of the first and second electromechanical screw jacks during a known period of time;
• based upon the sensed rotational movements, determining a value relating to a rotational synchronization of the first and second electromechanical screw jacks;
• comparing the determined value to threshold values;
• and,
• when the determined value is outside a predetermined range of threshold values, providing a control signal for affecting rotational movement of at least one of the first and second electromechanical screw jacks.

A method for preventing a rack fault condition of a passenger boarding bridge, the passenger boarding bridge having a first electromechanical screw jack and a second electromechanical screw jack mounted one each adjacent first and second opposite sidewall surfaces thereof, respectively, the method comprising:

• using a sensor, sensing a quantity that is indicative of a differential between vertical motion of the first sidewall surface of the passenger boarding bridge relative to vertical motion of the second sidewall surface of the passenger boarding bridge;
• based upon the sensed quantity, determining a corrective action for reducing the differential, the corrective action including changing a rate of rotation of the first electromechanical screw jack to a non-zero value;
• and,
• providing a control signal for initiating the corrective action.

A method for determining an actual direction of rotation of an electromechanical screw, comprising:

• receiving at a first time t1 a first signal that is indicative of a first rotational orientation of the electromechanical screw;
• receiving at a second time t2 a second signal that is indicative of a second rotational orientation of the electromechanical screw;
• determining a time difference Δt between t1 and t2;
• and,
• determining that the actual direction of rotation is clockwise when the determined time difference is within a first predetermined range of values, and determining that the actual direction of rotation is counter-clockwise when the determined time difference is within a second predetermined range of values.