Offsetting link assembly for folding luffing jib

• US 5,842,587 A
• Filed: 08/19/1997
• Issued: 12/01/1998
• Est. Priority Date: 03/04/1996
• Status: Expired due to Term

• Current Assignee: Manitowoc Cranes LLC (The Manitowoc Company, Inc.)
• Original Assignee: Manitowoc Crane Companies LLC
• Inventors: Wanek, Michael J., Krajnik, Daniel L., Walker, Robert J.
• Primary Examiner(s): Brahan, Thomas J.
• Application Number:
  US08/916,738
• Time in Patent Office: 469 Days
• Field of Search: 212/177, 212/299, 212/300, 212/347
• US Class Current: 212/177
• CPC Class Codes: B66C 23/82 Luffing gear

Abstract

A crane boom and luffing jib assembly have an offsetting link to allow the luffing jib to fold back and under the main boom for assembly of the boom and luffing jib assembly on a construction site where the entire length of the boom and luffing jib cannot be laid out during assembly. A method of assembling the crane boom and luffing jib comprises the steps of assembling the luffing jib and boom, the luffing jib pivotally attached to the jib connection pivot, the luffing jib folded back and under the boom along a ground surface, the hinged connection allowing neutral axis of the jib boom section to be offset relative to the boom connection pivot; attaching the boom to a crane; raising the boom top upwardly, allowing the jib top to travel along the ground surface until the luffing jib is lifted off the ground surface; causing the jib boom section to be aligned with the jib connection pivot; and inserting hinge pins into the hinged connection to lock the jib boom section in axial alignment with the jib connection pivot. wherein the luffing jib is initially folded back and under the crane boom.

Claims

1. A crane boom and luffing jib assembly, comprising:

(a) a crane boom having a boom top and a longitudinal neutral axis;

(b) a luffing jib having a jib butt section pivotally secured to the boom top about a jib connection pivot, a jib boom section pivotably secured to the jib butt section, the jib boom section having a longitudinal neutral axis; and

(c) an offsetting link structure connecting the jib boom section to the jib butt section such that, when the luffing jib is in a folded set-up configuration with the luffing jib folded back and under the crane boom, the link structure allows the jib boom section to move closer to the crane boom than it could if the jib butt and boom sections were in their operational relationship.

2. The crane boom and luffing jib assembly of claim 1, wherein the jib connection pivot is located near the boom neutral axis.

3. A crane boom and luffing jib assembly, comprising:

(a) a crane boom having a boom top;

(b) a luffing jib, comprising a jib butt section pivotally secured to the boom top, a jib boom section pivotally secured to the jib butt section, and a jib top section secured to the jib boom section, each jib section having a longitudinal neutral axis and each jib section having upper and lower chords in relation to a ground surface when the crane boom is raised and the luffing jib is extended parallel to the ground surface; and

(c) an offsetting link structure connecting chords of the jib boom section to chords of the jib butt section, the offsetting link being capable of holding the jib boom and butt sections in both a fixed operational relationship and a folded set-up relationship in which the longitudinal neutral axis of the jib boom section is offset relative to the longitudinal neutral axis of the jib butt section.

4. The crane boom and luffing jib assembly of claim 3, wherein the jib top section has a wheel at an outermost end.

5. The crane boom and folding luffing jib assembly of claim 3, wherein the offsetting link comprises:

(a) a pair of side brackets connected by cross braces;

(b) each side bracket comprising a pair of plates spaced apart from each other to form a channel to receive the ends of the lower chords of the jib sections between lower ends of the respective pairs of plates and joined to the offsetting link by an axle pin extending through aligned holes in the plates and the ends of the chords, and the upper chords of the jib sections received between upper ends of the respective pairs of plates, the upper chords of the jib butt section connected to an upper end of the offsetting link by hinge pins extending through aligned holes in the plates and an end of the jib butt section upper chords, and the upper chords of the jib boom section connected to the upper end of the offsetting link by pins extending through a second hole in the plates aligned with holes in an end of the upper chords of the jib boom section.

6. The crane boom and luffing jib assembly of claim 5, further comprising a stop lug between the upper ends of the plates to engage an abutment member attached to an end of the upper chords of the jib butt section to limit the degree of rotation about the axle pins when the hinge pins are removed.

7. The crane boom and luffing jib assembly of claim 6 wherein the hinge pins are removed by a pin puller, comprising:

(a) a winch carrying a cable, the cable passing through a pulley located between the upper ends of the pairs of plates;

(b) the cable attached to the hinge pins, such that taking up cable on the winch causes the hinge pins to be removed from the holes in the offsetting link, thereby allowing the jib boom section to rotate about the axle pin.

8. An offsetting link pivotally connecting two sections of a luffing jib together so that the sections are able to move between an operational relationship and an offset relationship each section having upper and lower chords, the link comprising a pair of side brackets connected by cross-braces, each side bracket comprising a pair of plates spaced to receive an end of a jib section chord therebetween, the chords being retained in the brackets by pins, wherein:

(a) each side bracket has a hole in a lower end of the bracket aligned with holes in an end of the lower chords of the jib sections, and axle pins extending through the holes in the side brackets and through the holes in the lower chords of the jib sections to secure the jib sections to each other and to the offsetting link;

(b) each side bracket has two holes in an upper end of the bracket, one of the holes being aligned with holes in an end of the upper chords of each of the jib sections;

(c) the upper chords of one jib section are secured to the offsetting link by a hinge pin, the upper chords of the other jib section are secured to the offsetting link by a second pin; and

(d) a stop lug is positioned between the plates at the upper end of each bracket to engage an abutment member on the end of the upper members of one of the jib sections to limit the degree of offset allowable when the hinge pins are removed.

9. A crane comprising:

(a) an upper works rotatably mounted upon a mobile lower works, the upper works rotatable about a vertical swing axis;

(b) a boom having a longitudinal neutral axis and upper and lower chords spaced outwardly from the boom longitudinal neutral axis to provide buckling strength to the boom, and a luffing jib connection pivot being near enough to the boom longitudinal neutral axis so that the axis of the connection pivot is between two planes, each of which is parallel to the boom longitudinal neutral axis and defined respectively by upper and lower faces of the boom;

(c) a luffing jib pivotally connected to the boom at the luffing jib connection pivot, the luffing jib also having a longitudinal neutral axis and upper and lower chords spaced outwardly from the jib longitudinal neutral axis to provide buckling strength to the jib, with the jib connection pivot being near enough to the jib longitudinal neutral axis when the jib is in an operational configuration so that the axis of the connection pivot is between two planes, each of which is parallel to the jib longitudinal neutral axis and defined respectively by upper and lower faces of the luffing jib;

(d) said jib including a hinge longitudinally spaced from said luffing jib connection pivot to allow the longitudinal neutral axis of the boom or the jib to be offset relative to the jib connection pivot.

10. The crane of claim 9, wherein the hinge joins a jib butt section to a jib boom section, allowing the longitudinal neutral axis of the jib to be offset relative to the jib connection pivot.

11. The crane of claim 9, further comprising at least one luffing jib pendant and first and second masts for raising and lowering the luffing jib, and a luffing jib backstop assembly.

12. The crane of claim 9, wherein said hinge is part of an offsetting link which comprises a pair of side brackets connected by cross-braces, each side bracket comprising a pair of parallel plates spaced to receive an end of the boom or jib chords therebetween, the chords retained in the brackets by pins.

13. The crane of claim 12, the hinge further comprising a stop lug positioned between the plates at an upper end of each bracket to engage an abutment member on the end of the upper chords of the boom or the jib to limit the degree of offset allowable when the pins are removed.

14. The crane of claim 10, wherein the hinge is part of an offsetting link which comprises:

(a) a pair of side brackets connected by cross-braces, each side bracket comprising a pair of parallel plates spaced to receive an end of an upper or lower chord therebetween, the chords retained in the brackets by pins;

(b) each side bracket having a hole in a lower end of the bracket aligned with a hole in an end of the lower chords of the jib butt section and jib boom section, and an axle pin extending through the holes in the side brackets and through holes in the lower chords to secure the jib boom section and the jib butt section to each other and to the offsetting link;

(c) each side bracket having two holes in an upper end of the bracket, one of the holes aligned with holes in the ends of each of the upper chords of the jib butt section, the jib butt section upper chords secured to the offsetting link by a hinge pin, the other of the holes in the side brackets aligned with holes in the upper chords of the jib boom section, the upper chords of the jib boom section secured to the offsetting link by a pin; and

(d) a stop lug positioned between the plates at the upper end of each bracket to engage an abutment member on the end of the upper chords of the jib butt section to limit the degree of offset allowable when the hinge pins are removed.

15. A crane boom and hinged luffing jib in a folded set-up configuration, comprising:

(a) a crane boom having a neutral axis and a boom top having an outer surface non-parallel to the neutral axis;

(b) a luffing jib also having a neutral axis, and including a jib section and a butt section hinged thereto, the luffing jib pivotally affixed to the boom top near the boom top neutral axis, the luffing jib being folded back and under the boom along a ground surface in the set-up configuration wherein the jib neutral axis is parallel to the boom neutral axis and said jib butt section extends along said boom outer surface.

16. A method of assembling a crane boom and luffing jib, the boom having a boom top, a longitudinal neutral axis and a jib connection pivot on the boom top, the luffing jib having a jib butt section, a jib boom section having a longitudinal neutral axis, a jib top section and a hinged connection connecting the jib butt section and jib boom section, comprising the steps of:

(a) assembling the luffing jib and boom, the luffing jib being pivotally attached to the jib connection pivot, the luffing jib also being folded back and under the boom along a ground surface, the hinged connection allowing the neutral axis of the jib boom section to be offset relative to the boom connection pivot;

(b) attaching the boom to a crane;

(c) raising the boom top upwardly, causing the jib top section to travel along the ground surface until the luffing jib is lifted off the ground surface;

(d) causing the neutral axis of the jib boom section to be aligned with the jib connection pivot; and

(e) inserting pins into the hinged connection to lock the jib boom section in axial alignment with the jib connection pivot.

17. The method of claim 16, wherein the jib top travels along the ground surface on a wheel attached to the jib top.

18. The method of claim 16 wherein the jib connection pivot is located near the longitudinal neutral axis of the boom.