AU749824B2 - Crawler link - Google Patents

Description

Crawler Link Field Of Invention This present invention relates to crawler belts, and more particularly to the lug face profile of a crawler belt link.

Definitions In the specification the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and "comprises".

Background of the Invention ~Large excavating equipment, such as a mining shovel, drag line, and the like, are movable on crawler belts. Each belt engages rotatable drive tumbler which drive the belt. The drive tumbler has teeth which engage the belt, and transfer torque from the tumbler to the belt.

The belt is formed from a plurality of crawler links joined together.

Conventional links have lugs, such as shown in Fig.l 1, incorporate a single curved surface for engaging the tumbler and driving the link. These single surface lugs have a tendency to climb up on the tumbler when the torque on the belt is opposite the torque on the drive tumbler. This condition occurs when the excavating equipment is travelling forward down a slope when the machine weight is forcing the belt around the tumbler.

Brief Summary Of The Invention The present invention provides a crawler belt link including a link body having an upper -1 surface, and a lug extending upwardly from the upper surface to a lug top. The lug has a first face Shich is engageable with a drive tumbler. A first surface engageable with the drive tumbler, said dQ.

first surface defining a first portion of the face extends from said lug top to a first surface edge.

A second surface engageable with the drive tumbler, said second surface defining a second portion of said face extends toward said link body upper surface from the first surface edge wherein said first surface defines an acute angle B with a plane defined by said link body upper surface, and said second surface defines an acute angle A with said plan, and angle B is less than angle In one aspect of the invention, the crawler belt link lug has a second face facing away from said first face. In one embodiment of the invention the crawler belt link first surface provides a mechanical advantage which is greater than In a second aspect the present invention provides a crawler belt link engageable with a drive tumbler, said link comprising: a link body having a substantially planar upper surface; i a lug extending upwardly from said upper surface to a lug top; a substantially planar engagement surface of said lug engagebale with the drive tumbler, said engagement surface defining an acute angle B with said planar upper surface, and :::.extending from said lug top to an engagement surface edge; and a substantially planar drive surface of said lug engageable with the drive tumbler, said drive surface defining an acute angle A with said planar upper surface, and extending toward said link body upper surface from said engagemnint surface edge, wherein when said lug engages the tumbler, siad engagemnt surfacae initially engages the tumbler and guides th elug into full engagemnt with the tumbler, and said drive surface transfers a load exerted by the tumbler to the lug to drive said link, wherein angle B is less than angle A.

A general advantage of preferred embodiments the present invention is that they provide a tumbler driven crawler link having a lug which does not have a tendency to climb up on the tumbler when the torque on the belt is opposite the torque on the drive tumbler. This objective is accomplished by providing a multi-surface lug profile which is guided into engagement with the tumbler.

The foregoing and other advantages of the present invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention.

Brief Description of the Drawings Figs. la-d show prior art link drive lug profiles; Fig. 2 is a two stage lug drive profile incorporating the present invention; Fig. 3 is the link of Fig. 2 engaging a tumbler; Fig. 4 is prior art lug profile superimposed over the lug profile of Fig. 2 showing the engagement of the two profiles with a tumbler.

Detailed Description of the Preferred Embodiment As shown in Fig. 2 and 3, a crawler link 10 for use in an endless crawler belt 11 has a base 12 with pair of lugs 14 (one shown) which engage the rotatably driven drive tumbler 16 to drive the link 10, and thus the belt 11. The link base 12 includes a plurality of forwardly and rearwardly facing fingers 15. A hole 17 is formed in each finger 15, and is aligned with the holes 17 in the adjacent fingers 15. The endless belt 10 11 is formed by interdigitating the fingers 15 of adjacent links 10, such that the holes 17 in the interdigitated fingers 15 are aligned, and a pin 19 is inserted through the holes 17 to couple the links 10 together.

Each lug 14 on a link 10 extends from the base 12 and terminates at a lug top 23. and has a leading face and a trailing face. Each face of the lug 14 has a profile which defined by two surfaces 20. 22 for engaging the tumbler 16 and then transferring a force from the tumbler 16 to the link 10 to drive the belt 11. The first surface 20 is an engagement surface which initially engages the tumbler 16, and guides the lug 14 into full engagement with tumbler 16. The second surface 22 is a main driving surface, and transfers the loads between the link 10 and the tumbler 16.

2 In one embodiment shown in Fig. 2, the lug profile on each face 18, 24 is defined by a pair of joined nonparallel sides of stacked upper and lower symmetrical trapezoids 26, 24.The lower trapezoid is defined by lower parallel sides 28, 30 and nonparallel sides 36, 42 joining the lower parallel sides 28, 30. The upper trapezoid is defined by upper parallel sides 32, 34 and nonparallel sides 38, 40 joining upper the parallel sides 32, 34.

The lower side 28 of the lower trapezoid 24 is adjacent to the link base 12, and is longer than the upper side 30 of the lower trapezoid 24 to define the second surface of the lug along the nonparallel side 36 having an angle A. The length of the upper side 30 of the lower trapezoid 24 is equal to the length of the lower side 32 of the upper trapezoid 26, and the length of the upper side 34 of the upper trapezoid 26 is shorter than the lower side 32 of the upper trapezoid 26 to define the first surface of the lug 14 along the nonparallel side 38 of the upper trapezoid 26 having an angle B. Angle B is less than angle A to provide the two distinct surfaces 20, 22.

The profile of the lug trailing face 18 is defined by the joined, forward facing nonparallel sides 36, 38 of each trapezoid 24, 26, and the profile of the lug trailing face is defined by the joined, rearward facing nonparallel sides 40, 42 of each trapezoid 24, 26. Each nonparallel side defines a distinct surface 20, 22, and each pair 5 of the two joined distinct surfaces 20, 22 defines the profile of the particular lug face.

Substantially identical lug face profiles are defined on each lug face 18, 21 to provide a bidirectional crawler belt which can reverse direction by reversing the rotational direction of the tumbler. Although substantially identical lug face profiles are disclosed, it should also be understood that the lug profile on each face can be 2 0 different, and one lug face profile can have a single surface without departing from the scope of the present invention. Preferably, the surfaces of the lug profile on each face are substantially straight to simplify manufacturing. However, two or more curved or straight surfaces can be provided depending upon the tumbler profile. The lug comers can be rounded, and filets added to simplify manufacturing.

-4- The lug face multiple surface profile provides a distinct advantage over prior art lugs, such as shown in Fig. 1. Prior art lugs having a single surface have a tendency to climb up on the drive tumbler, and require a greater force to engage the tumbler. As shown in Fig. 4, an interference 25, 27 exists between the single curved drive surface of the prior art lugs 5, 7 and the tumbler 16. The interference can cause the lug 5 to climb up on the tumbler 16, or require additional force to overcome the interference to urge the lug 5, 7 into engagement with the tumbler 16. This additional force reduces the force available for driving the belt. By providing a multi-surface lug face profile having an engagement surface 22, as disclosed herein, the lug 14 10 smoothly engages the tumbler 16, thus reducing the tendency to climb on the tumbler 16, and reducing the force required to engage the tumbler 16.

The engagement surface 20 of the present invention provides a mechanical advantage to ensure proper engagement of the tumbler 16 with the lug 14. As shown in Fig. 3, the mechanical advantage is determined by calculating the ratio of 15 moments acting on particular points of the lug using the following equation: M. A. (Lever Arm #1 x Load at WP D)/(Lever Arm #2 x Load at WP A) Lever Arm #1 distance between WP D and WP B.

WP D work point D (pivoting connection between adjacent links).

2 C WP B arbitrary work point chosen at base of lug.

Lever Arm #2 distance between WP A and WP B.

WP A work point at point of contact between lug and tumbler.

Load at WP D= weight of the link.

Load at WP A= force exerted by the tumbler on the lug at WP A.

A mechanical advantage which is greater than 1.0 ensures that the lug engages the tumbler without climbing. As can be seen, the mechanical advantage will change when the tumbler engagement changes from the engagement surface 20 to the drive surface 22.

I While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.

**ee

Claims (10)

1. A crawler belt link comprising: a link body having an upper surface; a lug extending upwardly from said upper surface to a lug top, and having a first face which is engagebale with a drive tumbler; a first surface engageable with the drive tumbler, said first surface defining a first portion of said face, and extending from said lug top to a first surface edge; and a second surface engageable with the drive tumbler, said second surface defining a second portion of said face extending toward said link body upper surface from said first surface edge, wherein said first surface defines an acute angle B with a plane defined by said link body .upper surface, and said second surface defines an acute angle A with said plane, and angle B is less than angle A. oo 15

2. The crawler belt link of claim 1, in which said lug has a second face facing away from said first face, wherein said second face includes: eee.ee a second face first surface engageable with the the drive tumbler, said second face first surface defining a first portion of said second face, and extending from said lug top to a second face first surface edge; and a second face second surface engageable with the drive tumbler, said second face second surface defining a second portion of said second face extending toward said link body upper surface from said second face first surface edge.

03. The crawler belt link of claim 1, in which said first surface of said first face rovides a mechanical advantage which is greater than 9q

4. The crawler belt link of claim 1, in which said second surface intersects said link body upper surface.

5. The crawler belt link of claim 1, in which said first and said second surfaces are substantially planar.

6. A crawler belt link engageable with a drive tumbler, said link comprising: a link body having a substantially planar upper surface; a lug extending upwardly from said upper surface to a lug top; a substantially planar engagement surface of said lug engagebale with the drive tumbler, said engagement surface defining an acute angle B with said planar upper surface, and .extending from said lug top to an engagement surface edge; and 5 a substantially planar drive surface' of said lug engageable with the drive tumbler, said drive surface defining an acute angle A with said planar upper surface, and extending toward •.said link body upper surface from said engagement surface edge, wherein when said lug engages the tumbler, said engagement surface initially engages the tumbler and guides the lug into full .:e.ei i engagement with the tumbler, and said drive surface transfers a load exerted by the tumbler to the lug to drive said link, wherein angle B is less than angle A.

7. The crawler belt link of claim 6, in which said lug has a second face facing away from said engagement surface, wherein said second face includes: a second face engagement surface engageable with the drive tumbler, said second face engagement surface defining a first portion of said second face, and extending from said lug top to a second face engagement surface edge; and a second face drive surface engageable with the drive tumbler, said second face drive surface defining a second portion of said second face extending toward said link body upper surface from said second face engagement surface edge.

8. The crawler belt link of claim 6, in which said body is pivotally connectable to an adjacent crawler belt link at a pivoting connection, and said engagement surface provides a mechanical advantage which is greater than

9. The crawler belt link of claim 6, in which drive surface intersects said link body upper surface.

"10. A crawler belt link substantially as described herein in the detailed description with reference to the drawings. DATED THIS EIGHTH DAY OF MAY 2002. BUCYRUS INTERNATIONAL, INC. BY PIZZEYS PATENT AND TRADE MARK ATTORNEYS