Crane with self-raising mast

A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, said boom being supported by boom hoist rigging and a moving mast pivotally connected to the upper works, said boom hoist rigging being connected between a rearward portion of said upper works and an upper end of said mast, and boom pendants being connected between the upper end of said mast and said boom, wherein said crane further comprises self-raising mast assembly for raising and lowering the mast when said mast is not connected to the boom and is not supportable by the boom hoist rigging, said self-raising mast assembly comprising:

• a) a mast raising yoke pivotally connected to the upper works and having an axis of rotation, said mast raising yoke having a rearward arm configured to engage and support said mast when said mast is between an approximately horizontal stored position towards the rearward portion of the upper works and an approximately vertical position, said rearward arm being disengaged from said mast when said mast is supported by said boom hoist rigging;
• b) a hydraulic mast raise cylinder pivotally connected between the upper works and said mast raising yoke, said hydraulic mast raise cylinder being extendable and retractable so as to rotate said mast raising yoke about said axis of rotation;
• and
• c) a hydraulic system for controlling the extension and retraction of said hydraulic mast raise cylinder.

A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, said boom being supported by boom hoist rigging and a moving mast pivotally connected to the upper works, said boom hoist rigging being connected between a rearward portion of said upper works and an upper end of said mast, and boom pendants being connected between the upper end of said mast and said boom, wherein said crane further comprises self-raising mast assembly for raising and lowering the mast when said mast is not connected to the boom and is not supportable by the boom hoist rigging, said self-raising mast assembly comprising:

• a) a mast raising yoke pivotally connected to the upper works and having an axis of rotation that is coincident with the pivotal connection of the mast to the upper works, said mast raising yoke having a rearward arm and a forward arm, said rearward arm being configured to engage and support said mast when said mast is between an approximately horizontal stored position toward the rearward portion of the upper works and an approximately vertical position, said forward arm being configured to engage and support said mast when said mast is near a horizontal position towards a forward portion of the crane, said rearward arm and said forward arm being disengageable from said mast when said mast is supported by said boom hoist rigging;
• b) a hydraulic mast raise cylinder pivotally connected between the upper works and said mast raising yoke, said hydraulic mast raise cylinder being extendable and retractable so as to rotate said mast raising yoke, the mast being raised or lowered by the rotation of said mast raising yoke when said mast is engaged by said rearward arm or said forward arm;
• c) a hydraulic system for controlling the extension and retraction of said hydraulic mast raise cylinder;
• and
• d) a microprocessor-based controller for controlling said hydraulic system, the control of said hydraulic system being coordinated with extension or contraction of the boom hoist rigging.

A method of self-raising a mast for a crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, said boom being supported by boom hoist rigging and a mast pivotally connected to the upper works, said crane further having a self-raising mast assembly for controlling the position of the mast when said mast is not connected to the boom and is not supportable by the boom hoist rigging, said self-raising mast assembly comprising a mast raising yoke pivotally connected to the upper works and having an axis of rotation, a hydraulic mast raise cylinder pivotally connected between the upper works and the mast raising yoke, and a hydraulic system for controlling the mast raise cylinder, said method comprising the sequential steps of:

• a) engaging the mast with the mast raising yoke when the mast is in a rearwardly extending stored position on a rearward portion of the upper works;
• b) extending the mast raise cylinder to rotate the mast raising yoke in a first direction so as to pivot the mast upwardly from the stored position to a forwardly leaning position;
• c) supporting the mast with the boom hoist rigging when the mast is in the forwardly leaning position;
• d) retracting the mast raise cylinder to rotate the mast raising yoke in a second direction so as to disengage said mast raising yoke from said mast when the mast is supported by the boom hoist rigging;
• e) extending the boom hoist rigging to lower the mast towards a forwardly extending fully forward position;
• f) engaging the mast with the mast raising yoke when the mast is near the fully forward position;
• g) extending the mast raise cylinder to rotate the mast raising yoke in the first direction so as to pivot the mast downwardly to the fully forward position;
• and
• h) connecting the mast to the boom.

A method of self-raising a mast for a crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, said boom being supported by boom hoist rigging and a mast pivotally connected to the upper works, said crane further having a self-raising mast assembly for controlling the position of the mast when said mast is not connected to the boom and is not supportable by the boom hoist rigging, said self-raising mast assembly comprising a mast raising yoke having a rear ward arm and a forward arm pivotally connected to the upper works and having an axis of rotation that is aligned with an axis of rotation of said mast, a hydraulic mast raise cylinder pivotally connected between the upper works and the mast raising yoke, and a hydraulic system for controlling the mast raise cylinder, said method comprising the sequential steps of:

• a) engaging the mast with the rearward arm of the mast raising yoke when the mast is in a rearwardly extending stored position on a rearward portion of the upper works, said rearward arm having an engagement slot that engages a lifting pin on the mast;
• b) extending the mast raise cylinder to rotate the mast raising yoke in a first direction so as to pivot the mast upwardly from the stored position to a forwardly leaning position;
• c) retracting the mast raise cylinder to rotate the mast raising yoke in a second direction so as to disengage the rearward arm of the mast raising yoke from said mast while the mast is in the forwardly leaning position;
• d) supporting the mast with the boom hoist rigging while the mast is in the forwardly leaning position;
• e) extending the boom hoist rigging to lower the mast towards a fully forward position;
• f) engaging the mast with the forward arm of the mast raising yoke when the mast is near the fully forward position, said forward arm having an engagement slot that engages the lifting pin on the mast;
• g) extending the mast raise cylinder to rotate the mast raising yoke in the first direction so as to pivot the mast downwardly to the fully forward position in front of the upper works;
• h) connecting the mast to the boom;
• i) retracting the mast raise cylinder to rotate the mast raising yoke in the second direction so as to pivot the mast upwardly from the fully forward position in front of the upper works;
• and
• j) retracting the boom hoist rigging to raise the mast and lift the boom into a crane operational range.