Controlling operations of a reach tower crane

A system for controlling an operation of a reach tower crane having a cab, a vertical boom capable of being derricked and telescopically moved in multiple stages, and a swingable horizontal boom connected with a head of said vertical boom so that the horizontal boom can be telescopically moved in multiple stages and be derricked, wherein said horizontal boom can be pirouetted in a widthwise direction of said vertical boom from an operational position to a storage position parallel to a side of said vertical boom, said system comprising:

• a first hydraulic actuator for providing telescopic notion of said vertical boom so as to extend or retract said vertical boom;
• a second hydraulic actuator for providing telescopic motion of said horizontal boom so as to extend or retract said horizontal boom;
• a plurality of sensors for detecting conditions of said actuators;
• a hydraulic circuit for controlling said first find second hydraulic actuators, an unloader valve being contained in said hydraulic circuit, said unloader valve having an operational position and an unloading position, whereby said unloader valve being in its unloading position prevents extension of either of said vertical boom and said horizontal boom while permitting retraction of either of said vertical boom and said horizontal boom;
• and
• a controller for receiving signals from said plurality of sensors and for providing control signals to said actuators in accordance with the signals from said sensors, and for actuating said unloader valve to its unloading position when one of said sensors is out of order.

A system for controlling an operation of a reach tower crane having a cab, a vertical boom capable of being derricked and telescopically moved in multiple stages, and a swingable horizontal boom connected with a head of said vertical boom so that the horizontal boom can be telescopically moved in multiple stages and be derricked, wherein said horizontal boom can be pirouetted in a widthwise direction of said vertical boom from an operational position to a storage position parallel to a side of said vertical boom, said system comprising:

• a coupling pin having a locked position, for locking said horizontal boom to said vertical boom when said horizontal boom is in its operational position, and an unlocked position;
• an operational position detection sensor for detecting that said horizontal boom is in its operational position;
• a storing completion detection sensor for detecting that said horizontal boom is in its storage position;
• an unlocking completion detection sensor for detecting that said coupling pin is in its unlocked position;
• a first actuator for actuating said coupling pin between its locked position and its unlocked position;
• a second actuator for effecting telescopic movement of said horizontal boom;
• a third actuator for pirouetting said horizontal boom between its operational position and its storage position;
• a three position operating valve for boom telescopic notion, said three position operating valve having a hydraulic power source port, a tank port, a first actuator port, and a second actuator port;
• first, second, and third solenoid selector valves;
• said first solenoid selector valve having a first position and a second position, whereby in said first position said first solenoid selector valve connects one of said first and second actuator ports to both said second solenoid selector valve and said first actuator and connects the other of said first and second actuator ports to said third solenoid selector valve, and whereby in said second position said first solenoid selector valve connects said first and second actuator ports to said second actuator;
• said second solenoid selector valve having a first position and a second position, whereby in its first position said second solenoid selector valve connects said first solenoid selector valve to said third actuator, and whereby in its second position said second solenoid selector valve connects said second solenoid selector valve to a check valve to block any flow from said first solenoid selector valve through said second solenoid selector valve to said third actuator;
• a third solenoid selector valve having a first position and a second position, whereby in its first position said third solenoid selector valve connects said first solenoid selector valve to said first actuator, and whereby in its second position said third solenoid selector valve connects said first solenoid selector valve to said third actuator;
• a controller for receiving a signal from each of said sensors and for transmitting a control signal to each of said solenoid selector valves.

A method for controlling an operation of a reach tower crane having a vertical boom capable of being derricked and telescopically moved in multiple stages, and a swingable horizontal boom connected with a head of said vertical boom so that the horizontal boom can be telescopically moved in multiple stages and be derricked, wherein said horizontal boom can be pirouetted in a widthwise direction of said vertical boom from an operational position to a storage position parallel to a side of said vertical boom, wherein said horizontal boom can be locked to said vertical boom by a first locking apparatus when said horizontal boom is in said storage position, and wherein said horizontal boom can be locked to said vertical boom by a second locking apparatus when said horizontal boom is in said operational position, said method comprising the steps of:

• operating said vertical boom to erect said vertical boom;
• detecting when said vertical boom is erected at a predetermined derricking angle;
• starting to unlock said first locking apparatus after said vertical boom has been detected to be erected at said predetermined derricking angle;
• starting to pirouette said horizontal boom after the unlocking of said first locking apparatus is completed;
• starting to lock said second locking apparatus after said horizontal boom has pirouetted a predetermined pirouetting angle;
• starting to erect said horizontal boom after the locking of said second locking apparatus is completed;
• and
• then starting to telescopically move and derrick said horizontal boom.

A method for controlling an operation of a reach tower crane having a vertical boom capable of being derricked and telescopically moved in multiple stages, and a swingable horizontal boom connected with a head of said vertical boom so that the horizontal boom can be telescopically moved in multiple stages and be derricked, wherein said horizontal boom can be pirouetted in a widthwise direction of said vertical boom from an operational position to a storage position parallel to a side of said vertical boom, wherein said horizontal boom can be locked to said vertical boom by a first locking apparatus when said horizontal boom is in said storage position, and wherein said horizontal boom can be secured with respect to said vertical boom by a second locking apparatus when said horizontal boom is in said operational position, said method comprising the steps of:

• retracting said horizontal boom to its shortest length;
• positioning said vertical boom at a predetermined derricking angle;
• starting to lower said horizontal boom after said horizontal boos has been retracted to its shortest length and said vertical boom has been positioned at said predetermined derricking angle;
• starting to unlock said second locking apparatus after said horizontal boom has been lowered to a maximum angle of lowering;
• starting to pirouette said horizontal boom after the unlocking of said second locking apparatus is completed;
• starting to lock said first locking apparatus after said horizontal boom has pirouetted a predetermined pirouetting angle;
• and
• starting to lower said vertical boom after the locking by said first locking apparatus is completed.