Box boom lift arm assembly

• US 5,993,139 A
• Filed: 03/25/1998
• Issued: 11/30/1999
• Est. Priority Date: 06/30/1997
• Status: Expired due to Fees

• Current Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Original Assignee: Caterpillar Incorporated
• Inventors: Deneve, Jeffrey A., McMillan, Charles T., Loughrin, Owen S.
• Primary Examiner(s): Underwood, Donald W.
• Application Number:
  US09/048,249
• Time in Patent Office: 615 Days
• Field of Search: 414/722, 414/697, 414/700-715, 212/347, 52/111, 52/116, 52/632, 52/731.2, 52/731.6, 52/732.1, 52/735.1, 29/897.2, 29/897.31, 228/165, 228/166, 228/667, 228/174, 228/182
• US Class Current: 414/722
• CPC Class Codes: B66F 9/065 non-masted mobile jacks of the garage type mounted on wheels or rollers B66F5/00
• CPC Class Codes: E02F 3/283 with a single arm pivoted directly on the chassis linkage mechanism for it E02F3/3405
• CPC Class Codes: E02F 3/34 with bucket-arms , i.e. a pair of arms, e.g. manufacturing processes, form, geometry, material of bucket-arms with a single arm E02F3/283 directly pivoted on the frames of tractors or self-propelled machines
• CPC Class Codes: E02F 3/3408 of the parallelogram-type
• CPC Class Codes: E02F 3/382 Connections to the frame; Supports for booms or arms devices to connect booms or arms to tractors or similar machines E02F3/627; pivot joint assemblies in particular E02F9/006

Abstract

The box boom lift arm assembly of the present invention includes a single plate steel top wall and a bottom wall connected with a substantially non-transverse weld to a pair of single plate steel inner side walls and a pair of single plate steel outer side walls to define a closed box section having a rectangular cross section along the entire length, varying only in height and width. The unique configuration and shape of the plates and the use of non-transverse weld during manufacturing improve the fatigue characteristics, load distribution and strength of the box boom lift arm assembly without increasing the weight of the machine.

Claims

1. A box boom lift arm assembly for a construction machine, comprising:

top and bottom walls extending a predetermined length, each of the top and bottom walls having a central portion with a predetermined width, a first end portion diverging outwardly from the central portion and terminating at a predetermined width greater than the predetermined width of the central portion and a bifurcated second end portion diverging outwardly in a substantial U-shape from the central portion opposite the first end portion and terminating at a predetermined width greater than the predetermined width of the central portion;

a pair of inner side walls having a predetermined length substantially equal to the length of the top and bottom walls, each of the pair of inner side walls having first and second ends and being disposed between the top and bottom walls and fixedly connected thereto substantially along the entire predetermined length of the inner side walls, the first ends of the inner side walls defining with the first end portions of the top and bottom walls a diverging end portion; and

a pair of outer side walls having a predetermined length, each of the pair of outer side walls having first and second ends and being fixedly connected at the first end to one of the pair of inner side walls at a predetermined location along the predetermined length of the inner side walls and disposed between the U-shape second end portion of the top and bottom walls and fixedly connected thereto, the second ends of the outer side walls defining with the second ends of the inner side walls and the second end portions of the top and bottom walls a bifurcated end portion having a pair of legs.

2. The box boom lift arm assembly of claim 1, wherein the pair of inner side walls and top wall are fixedly connected through a continuous non-transverse weld, the pair of inner side walls and the bottom wall are fixedly connected through a continuous substantially non-transverse weld and the pair of outer side walls and top and bottom walls are fixedly connected through a continuous non-transverse weld extending substantially along the predetermined length of the outer side walls.

3. The box boom lift arm assembly of claim 1, wherein the first end portions of the top and bottom walls are non-bifurcated and each includes a planar edge wherein the predetermined width is continuous and non-interrupted.

4. The box boom lift arm assembly of claim 2, wherein the bottom wall is made from first and second plates fixedly connected through a continuous transverse weld extending substantially across the predetermined width of the central portion of the bottom wall and the top wall is made from a single plate.

5. The box boom lift arm assembly of claim 4, wherein the top wall plate is formed along a first bend path at a predetermined location and angle and the first plate of the bottom wall is formed at a predetermined location and angle so that the top wall plate and bottom wall plate achieve the substantially predetermined equal length with the inner side wall plates.

6. The box boom lift arm assembly of claim 5, wherein each of the pair of inner side walls is a single flat plate having a transitional width at predetermined locations along the predetermined length thereof corresponding to the respective bends in the single plate of the top wall and the first plate of the bottom wall.

7. The box boom lift arm assembly of claim 1, including the first and second ends of the pair of inner side walls and the second end of the pair of outer side walls having a semi-circular shape, a pair of frame pin bosses disposed within the semi-circular second ends of the inner side walls and the second ends of the outer side walls and extending therebetween with each one of the pair of frame pin bosses being fixedly connected therealong to one of the pairs of legs and a coupler pin boss disposed within the semi-circular first ends of the pair of inner side walls and extending along the predetermined width of the diverging end portion and being fixedly connected therealong.

8. The box boom lift arm assembly of claim 1, including a closure plate fixedly connected to the pair of inner side wall plates and the top and bottom plates between the pair of legs to enclose the box boom lift arm assembly.

9. The box boom lift arm assembly of claim 1, wherein rack and dump stops are positioned at least one predetermined location on an outer surface of the top wall, the rack and dump stops including an outward projection having a contact surface elevated above the outer surface of the top wall.

10. The box boom lift arm assembly of claim 1, wherein spaced rack and dump stops are positioned at predetermined locations on an outer surface of the top wall, the rack and dump stops each including an outward projection having a contact surface elevated above the outer surface of the top wall.

11. The box boom lift arm assembly of claim 10, wherein the rack and dump stops are connected to a respective plate welded to the top surface of the top wall.

12. The box boom lift arm assembly of claim 1, including a lift pin boss plate assembly welded substantially at the central portion of the bottom wall and extending a predetermined length along the predetermined length of the bottom wall.