Crane boom having variable angle offset capability

• US 4,653,655 A
• Filed: 12/23/1985
• Issued: 03/31/1987
• Est. Priority Date: 12/23/1985
• Status: Expired due to Fees

• Current Assignee: Trust Company United States
• Original Assignee: Harnischfeger Corporation (Mitsui & Company Limited)
• Inventors: Rathi, Ram N., Vaerk, Lembit
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): Brahan, Thomas J.
• Application Number:
  US06/812,336
• Time in Patent Office: 463 Days
• Field of Search: 212/175, 212/177, 212/182, 212/187, 212/188, 212/266
• US Class Current: 212/300
• CPC Class Codes: B66C 23/702 with a jib extension boom

Abstract

A mobile crane having a boom and a boom extension connected thereto with a toggle linkage for connecting the boom extension to the boom to allow the boom extension to be offset from the boom by one of a plurality of predetermined angles. A pair of double links is pivotably attached to the boom extension while a pair of single links is pivotably attached to the upper sheave pin in the boom head. Both the single and double links have a hole in the opposite end. Either the single or double links also have a hole in at least one intermediate position. The link having one hole is then pinned to the other link having two holes, the hole selected in the second link determining the angles of offset when tension is applied to the linkage by pivoting the boom extension about the lower sheave pin after removal of the upper boom foot pins. Biasing devices are provided to cause the linkage, which pivots freely at both ends and in the middle, to toggle upward when tension thereon is released. A storage position is provided for storing the double links and the link connector pins so as to prevent interference with the other apparatus and loss of the connector pins when the linkage is not in use.

Claims

1. In a crane of the type having a crane boom and a boom extension angularly pivotable relative thereto, an apparatus for connecting said crane boom to said boom extension to permit a selection of one of several predetermined and fixable offset angles therebetween, said crane boom having a boom head with at least two vertically spaced apart sheave pins therein, said boom extension being pivotally connected to said boom about a lower of said vertically spaced apart pins, said connecting apparatus comprising:

a first link pivotably connected to an upper one of said sheave pins;

a second link pivotably connected to said boom extension;

each of said links having a hole at the end opposite its respective connection;

at least one of said links having a hole intermediate its length; and

a pin removably extendable through one of the holes of said at least one of said links and also through the end hole of the other of said links to thereby permit said boom extension to pivot about said lower sheave pin and thereby be angularly offset from said boom head by a predetermined angle depending on which of the holes of said at least one link is selected, so that impact loading of said links and pins in the event of boom bounce is prevented.

2. A crane as recited in claim 1 further comprising means for biasing said links upward so as to prevent interference with the rest of the apparatus when tension on the links is released.

3. A crane as recited in claim 2 wherein said biasing means includes a leaf spring, one end of which is affixed to one of the boom head and the boom extension and the other end of which bears on one of said links, said leaf spring so positioned and biased as to prevent said links from falling and interfering with the rest of the apparatus when tension on the links is released.

4. A crane as recited in claim 1 wherein said at least one link having an intermediate hole is said second link attached to said boom extension.

5. A crane as recited in claim 1 further comprising means for storing said second link and said removably extendable pin so as to prevent interference with the rest of the apparatus when said links are not in use.

6. A crane as recited in claim 1 wherein one of said links is a double link and the other of said links is a single link.

7. A crane as recited in claim 6 wherein said double link is said second link connected to said boom extension and said single link is said first link connected to said upper one of said sheave pins.

8. A crane of the type having a crane boom and a boom extension angularly pivotable relative thereto, said crane having an apparatus for connecting said crane boom to said boom extension to permit a selection of one of several predetermined and fixable offset angles therebetween, said crane boom having a boom head with at least two vertically spaced apart sheave pins therein, said boom extension being pivotably connected to said boom about a lower of said vertically spaced apart pins, said connecting apparatus comprising:

a first link pivotably connected to an upper one of said sheave pins;

a second link pivotably connected to said boom extension;

each of said links having a hole at the end opposite its respective connection;

at least one of said links having a hole intermediate its length;

a pin removably extendable through one of the holes of said at least one of said links and also through the end hole of the other of said links to thereby permit said boom extension to pivot about a lower one of said sheave pins and thereby be angularly offset from said boom head by a predetermined angle depending on which of the holes of said at least one link is selected; and

biasing means including a leaf spring, one end of which is affixed to one of the boom head and the boom extension and the other end of which bears on one of said links, said leaf spring so positioned and biased as to prevent said links from falling and interfering with the rest of the apparatus when tension on the links is released, so that impact loading of said links and pins in the event of boom bounce is prevented;

wherein said at least one link having an intermediate hole is said second link attached to said boom extension.

9. A crane as recited in claim 8 further comprising means for storing said second link and said removably extendable pin so as to prevent interference with the rest of the apparatus when said links are not in use.

10. A crane as recited in claim 8 wherein one of said links is a double link and the other of said links is a single link.

11. A crane as recited in claim 10 wherein said double link is said second link connected to said boom extension and said single link is said first link connected to said upper one of said sheave pins.

12. Apparatus for connecting a crane boom to a boom extension in a crane to permit a selection of one of several predetermined and fixable offset angles therebetween, said crane boom having a boom head with at least two vertically spaced apart sheave pins therein, said boom extension being pivotably connected to said boom about a lower of said vertically spaced apart pins, said connecting apparatus comprising:

a first link pivotably connected to an upper one of said sheave pins;

a second link pivotably connected to said boom extension;

each of said links having a hole at the end opposite its respective connection;

at least one of said links having a hole intermediate its length; and

a pin removably extendable through one of the holes of said at least one of said links and also through the end hole of the other of said links to thereby permit said boom extension to pivot about a lower one of said sheave pins and thereby be angularly offset from said boom head by a predetermined angle depending on which of the holes of said at least one link is selected, so that impact loading of said links and pins in the event of boom bounce is prevented.

13. An apparatus as recited in claim 12 further comprising means for biasing said links upward so as to prevent interference with the rest of the apparatus when tension on the links is released.

14. An apparatus as recited in claim 13 wherein said biasing means includes a leaf spring, one end of which is affixed to one of the boom head and the boom extension and the other end of which bears on one of said links, said leaf spring so positioned and biased as to prevent said links from falling and interfering with the rest of the apparatus when tension on the links is released.

15. An apparatus as recited in claim 12 wherein said at least one link having an intermediate hole is said second link attached to said boom extension.

16. An apparatus as recited in claim 12 further comprising means for storing said second link and said removably extendable pin so as to prevent interference with the rest of the apparatus when said links are not in use.

17. An apparatus as recited in claim 12 wherein one of said links is a double link and the other of said links is a single link.

18. An apparatus as recited in claim 17 wherein said double link is said second link connected to said boom extension and said single link is said first link connected to said upper one of said sheave pins.