AU5444801A

AU5444801A - Wear indicator for a low friction bearing

Info

Publication number: AU5444801A
Application number: AU54448/01A
Authority: AU
Inventors: Terri L. Lovekamp; Wayne R. Tanner; Kevin J. Wilkening
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2000-08-29
Filing date: 2001-07-17
Publication date: 2002-03-07
Also published as: CA2353280A1

Description

P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventors: Address for service in Australia: Invention Title: CATERPILLAR INC.

Terri L. LOVEKAMP, Wayne R. TANNER and Kevin J.

WILKENING

Freehills Carter Smith Beadle 101 Collins Street Melbourne Victoria 3000 Australia WEAR INDICATOR FOR A LOW FRICTION BEARING The following statement is a full description of this invention, including the best method of performing it known to us Freehills Carter Smith Beadle Melbourne\003856330 Printed 17 July 2001 (8:35) page 1 -lA- Description WEAR INDICATOR FOR A LOW FRICTION BEARING Technical Field This invention relates generally to a bearing arrangement and more specifically to a wear indicator for a low friction bearing which supports a linearly moveable member on a work machine.

Background Art In the construction and earthmoving industry work machines have implements that require frequent linear movement in order to properly position such implement relative to the work surface. One such *."*implement is the moldboard on a motor grader, which is supported by a mounting assembly attached to the motor grader frame. The moldboard mounting assembly includes pairs of upper and lower bearing retainers in which low friction bearings are mounted. The moldboard includes linear moveable members (moldboard rails), which are supported by the low friction bearings, and which allow the. moldboard to be moved linearly from side to side.

The low friction bearings not only support and allow movement of the moldboard and moveable members, they are also designed to act as sacrificial wear elements. As such, the low friction bearings also prevent the more expensive, retainers and moldboard rails from being damaged due to wear.

I -2- Bearing wear must be continually monitored so that the bearings can be replaced before wearing through. To monitor the amount of wear on the low friction bearings, it is often necessary to disassemble a portion of the moldboard mounting assembly and visually observe the condition of the low friction bearings. If the operator of the work machine does not properly monitor the amount of wear on the low friction bearings, the retainers or moldboard rails may be damaged and require replacement as well.

The present invention is directed to overcoming one or more of the above problems.

Disclosure of the Invention 15 In a one aspect of the present invention is disclosed a low friction bearing for supporting a linearly moveable member. The linear moveable member can be moved between a first position and a second .eo..i position by the operator of the motor grader. The low friction bearing includes a first side surface for supporting the moveable member and a second side which "engages a non-moveable member. The low friction bearing also has a first end and a second end, the distance between the first end and the second end is ooooo less than the distance between the first position and the second position. A marker is embedded in the low friction bearing at a predetermined distance from the second side surface so that repeated reciprocal movement of the moveable member causes wear to expose and deposit the marker on the moveable member.

;I~

In a second aspect of the present invention, is disclosed a motor grader having a main frame, a circle support assembly attached to the main frame, a moldboard mounting assembly attached to the circle support, a low friction bearing being retained on the mounting assembly, and a moldboard slidingly engaging the low friction bearing. The low friction bearing includes a first side surface for engaging the moldboard, a second side surface for engaging the mounting assembly, and a marker embedded in the low friction bearing. The marker is positioned so that it becomes exposed to and deposited on the moldboard after the low friction bearing has reached its wear limit.

15 In a third aspect of the present invention is disclosed a method for determining that a replacement limit of a low friction bearing has been reached including embedding a wear indicator within a ooooo S"low friction bearing, wearing the low friction bearing until the marker is exposed to a moveable member, and depositing the marker on the moveable member.

a Brief Description of the Drawings FIG. 1 is a right side elevational view of 25 the rear portion of a circle support of a moldboard mounting assembly and moldboard of a motor grader.

FIG. 2 is a right rear perspective view of a low friction bearing of the present invention.

FIG. 3 is a side elevational view of a low friction bearing positioned in a retainer.

FIG. 4 is a side elevational view of a low friction bearing positioned in a retainer with a retainer plate fastened to the retainer.

Best Mode for Carrying Out the Invention While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Referring now to FIG. i, there is shown a rear portion of a circle support 10, a moldboard mounting assembly 14 and a moldboard 18 of a motor eoee grader (not shown). The circle support 10 typically is suspended under the front frame of the motor grader (not shown). The circle support 10 includes a right side support arm 22 and a left side support arm (not shown). The support arm(s) 22 have a horizontal portion that extends along a top portion 24 of the 25 circle support 10 and a vertical portion 28 that extends downward and substantially perpendicular to the horizontal portion 24 of the circle support The vertical portion 28 of the support arms include a lower end 26 for pivotally attaching the moldboard mounting assembly 14. The moldboard mounting assembly 14 extends laterally and has a right hand end 30 and a left hand end (not shown). The moldboard mounting assembly 14 includes a pair of upper bearing retainers 34 (one shown) and a pair of lower bearing retainers 38 (one shown). One each of the upper bearing retainers 34 and lower bearing retainers 38 are located toward the right hand end 30 of the moldboard mounting assembly 14 and the other of the upper bearing retainers 34 and lower retainers 38 are located toward the left hand end of the moldboard mounting assembly 14. Each of the pairs of bearing retainers 34,38 are adapted to receive a low friction bearing 42 shown in Fig 2. Each of the pairs of bearing retainers 34,38 has a pair of retainer end 15 plates, two of which are shown in Fig 1 at 46. Each of the pairs of retainer end plates 46 are fastened to bearing retainers 34,38 to prevent the low friction bearings 42 from sliding out of the retainers as the moldboard 18 is moved from side to side, between a ao..

first position and a second position.

The moldboard 18 has a curved blade S. (moldboard blade) that extends traversely under the circle support 10, and includes an upper reinforcing channel 54 and a lower reinforcing channel 58, that *aaa..

25 extend laterally along the backside of the moldboard plate 50. The upper channel 54 carries a linearly moveable member such as an upper moldboard rail 64, while the lower channel 58 carries a linearly moveable member such as a lower moldboard rail 66. The upper and lower reinforcing channels 54,58 extend the length -6of the moldboard 18, and each are formed to create a triangular shaped reinforcement channel when welded to the back of the moldboard blade 50. The upper moldboard rail 62 and the lower moldboard rail 66 extend the length of the reinforcement channels 54,58 and are secured to their respective channels by welding. The upper moldboard rail 62 defines a back surface 74, a top surface 78, and an upper front surface 80. The lower moldboard rail 66 defines a back surface 82, a bottom surface 86, and a lower front surface 84. The upper and lower moldboard rails 62,66 each slidingly engage respective ones of the low friction bearings 42. A hydraulic cylinder (not shown) attaches at a first end to the moldboard mounting assembly 14 and at a second end to the moldboard 18. Actuation of the hydraulic cylinder oooo causes the moldboard 18 to move laterally between the first position and the second position.

One of the low friction bearings 42 of the present invention is illustrated in Fig 2. Low friction bearings 42 are typically manufactured of polymer compounds and often include a low friction material, such as TEFLON in the compound. The low friction bearings 42 typically engage the moldboard *25 rails 62,66 on three surfaces. Although the figures of the present application illustrate a shaped low friction bearing 42, it is possible to provide multiple low friction bearing members to support the required surfaces of each of the moldboard rails 62,66. A distance is defined between the first end 98 p and the second end 102. The distance is substantially equal to the width of the bearing retainers 34,38. The width of the bearing retainers 34,38 is substantially less than the distance that the moldboard 18 is capable of moving from between the first and second positions. A thickness 114 is defined as the distance from the first side surface 90 to the second side surface 94. A marker 118 is embedded within the low friction bearing 42 and has an inward marker surface 120 at a distance from the first side surface 90 to define a wear limit 122. In use, the first side surface 90 wears away toward the inward marker surface 120. The wear limit distance 122 represents the maximum amount that the low friction bearing 42 should 15 be worn away before being replaced. A pair of markers 118 are preferably located near the first end 98 and the second end 102 respectively of the low friction bearing 42, although a single marker 118 may be eooeu located at any distance between the first end 98 and e the second end 102 of the low friction bearing 42.

The marker 118 may be of any common material that is capable of leaving a visible mark on the abutting surfaces of the moldboard rail 62,66. A few examples of common marker materials include, but are not ooooe Su 25 limited to, ink, paint, and chalk. The low friction bearing 42 may be molded to encapsulate the marker 118 or a cavity 130 may be machined into the low friction bearing 42 to receive the marker 118. The marker 118 may further be incorporated into some other substrate.

For example, a piece of felt or foam may be impregnated with ink or paint. If the marker 118 is to be inserted into a machined cavity 130, the marking material and substrate may further be encapsulated in a plastic or metal housing.

Industrial Applicability During use of a motor grader, an operator positions a moldboard 18 to push or level dirt and rock. Operator controls allow the moldboard 18 to be rotated about a vertical axis and moved horizontally from side to side. The moldboard rails 62, 66 slide within the low friction bearings 42, while the low friction bearings 42 are held within their respective bearing retainers 34,38. When the moldboard 18 is pushing or leveling dirt, the moldboard 18 may be ~shifted from left to right to control the path of the moldboard 18. The forces created by pushing dirt, and the side to side movement of the moldboard 18 cause the low friction bearings 42 to wear. The amount of wear on the low friction bearings 42 should be monitored regularly to prevent the low friction bearings 42 from exceeding their designed wear limit 122, which if exceeded may result in damage to the moldboard rails 62,66 or bearing retainers 34,38. In 25 the past, proper monitoring of the low friction bearings 42 would require disassembling parts of the moldboard mounting assembly 14 in order to view the low friction bearings 42. Failure to replace the low friction bearings 42 after reaching the wear limit 122 may result in damage to the moldboard rails 62,66 or the retainers 34,38.

The present invention eliminates the need to disassemble parts the moldboard 18 by the incorporation of a marker 118 to create a visible mark on the moldboard rails 62,66 when the wear limit 122 has been reached. Repeated exposure of the marker 118 to the moldboard rails 62,66 increases the visibility of the mark on the moldboard rails 62,66. As the moldboard 18 is moved farther from side to side, the marker 118 forms a longer mark on the moldboard rails 62,66. Most motor graders have exposed portions of the moldboard rails 62,66 that are visible from the operator's cab. As a consequence, the operator can readily see the marks made on the moldboard rails 62,66 by the marker 118 without disassembling any parts of the moldboard mounting assembly 14.

Existence of marks on the moldboard rail 62,66 is a o* .certain indicator that the low friction bearings 42 need to be replaced. The marker material 118 may be of any color that will stand out against the moldboard rails 62,66.

o o 9

Claims

2. The bearing arrangement of claim 1, wherein said moveable member is manufactured from steel and low friction bearing is manufactured from a polymer.
3. The bearing arrangement of claim 1, wherein said marker is comprises chalk. I ~r I 1 -11-
4. The bearing arrangement of claim 3, wherein said chalk is encapsulated in a housing.
5. The bearing arrangement of claim i, wherein said marker comprises paint.
6. The bearing arrangement of claim i, wherein said marker comprises ink.
7. A motor grader having a frame, a circle support assembly attached to said frame, a moldboard mounting assembly attached to said circle support, a low friction bearing retained on said mounting assembly, a moldboard slidingly coupled to said low friction bearing wherein said low friction bearing comprises: a bearing material with a faster wear rate than that of a linearly moveable member; a first side surface for supporting engagement with said linearly moveable member; .a first end; a second end wherein said second end is a distance from said first end which is less than the S• 25 distance between a first position and a second position; and a marker embedded in said low friction bearing at a predetermined distance from said first side surface wherein repeated reciprocal movement of said moveable member causes said bearing member to -12- wear until said marker is exposed to, and deposited on said moveable member to provide a visible mark on the moveable member so as to indicate that a wear limit on said low friction bearing has been reached.
9. The motor grader of claim 6, wherein said marker is comprises chalk. The motor grader of claim 6, wherein said chalk is encapsulated in a housing.
11. The motor grader of claim 6, wherein said marker comprises paint. 15 12. The motor grader of claim 6, wherein said marker comprises ink.
13. A method for determining that a wear limit of a low friction bearing has been reached comprising: embedding a wear indicator within said low friction bearing at a predetermined distance from a first side surface; and wearing said low friction bearing until 25 exposing said wear indicator to a moveable member further depositing said wear indicator on said moveable member. ~1 I -13-
14. A low friction bearing substantially as hereinbefore described with reference to the accompanying drawings.
15. A method for determining that a wear limit of a low friction bearing has been reached having the steps substantially as hereinbefore described. DATED: 27 June 2001 Freehills Carter Smith Beadle Patent Attorneys for the Applicant: CATERPILLAR INC. 0S **ee So* Melboure\003856326 Printed 17 July 2001 (8:19)