(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0173203 A1
`(43) Pub. Date:
`Aug. 11, 2005
`Buckner
`
`US 20050173203A1
`
`(54)
`
`(76)
`
`(21)
`(22)
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`(60)
`
`BRAKE ELEMENT HAVING INTEGRATED
`WEAR SENSOR
`
`Inventor: Guy Brian Buckner, Brush Creek, TN
`(US)
`Correspondence Address:
`HOWARD & HOWARD ATTORNEYS, P.C.
`THE PINEHURST OFFICE CENTER, SUITE
`#101
`39400 WOODWARD AVENUE
`BLOOMFIELD HILLS, MI 48304-5151 (US)
`
`Appl. No.:
`
`10/989,846
`
`Filed:
`
`Nov. 16, 2004
`
`Related US. Application Data
`
`Provisional application No. 60/481,670, ?led on Nov.
`19, 2003.
`
`Publication Classi?cation
`
`(51) Int. Cl? ................................................... .. F16D 65/40
`(52) Us. 01. .................................................... ..188/1.11 W
`
`(57)
`
`ABSTRACT
`
`A brake element for use in applying a frictional braking
`force to a rotating brake rotor includes a backing plate and
`a pad of friction material mounted on the backing plate. The
`backing plate is formed With an integral Wear sensor portion
`in the form of a punched tab feature that is bent out of the
`mounting plate. A tip end of the Wear sensor resides beloW
`the level of the outer braking surface of the pad. When the
`pad Wears to the point Where the sensor tip is exposed, it rubs
`on the rotor and generates an audible signal.
`
`10
`
`[22
`
`12
`
`14
`
`16
`
`_//AVA
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`24
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`26
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`CATERPILLAR EXHIBIT 1008
`
`Page 1 of 4
`
`

`

`Patent Application Publication Aug. 11, 2005
`
`US 2005/0173203 A1
`
`FIG-1
`
`i /” f" /" r“
`
`18/
`
`\20
`
`""6 FIG-2
`
`1 0'
`
`24'
`
`[I 18/ \20‘
`
`FIG - 3
`
`Page 2 of 4
`
`

`

`US 2005/0173203 A1
`
`Aug. 11, 2005
`
`BRAKE ELEMENT HAVING INTEGRATED WEAR
`SENSOR
`
`the friction pad material. This ?exibility is not knoW to be
`available With the clip-on variety of Wear sensors.
`
`[0001] This application claims priority to US. Provisional
`Patent Application Ser. No. 60/481,670, ?led Nov. 19, 2003.
`
`BACKGROUND OF THE INVENTION
`
`[0002] 1. Technical Field
`
`[0003] This invention relates generally to brake elements,
`and more particularly to those used in automotive brake
`application that are ?tted With an audible Wear sensor.
`
`[0004] 2. Related Art
`
`[0005] It is knoWn in the art to attach a Wear sensor clip or
`some other necgabucak device to the backing plate of a
`brake element. When the pad Wears, the clip is eXposed and
`rubs on the brake rotor to generate an audible signal Which
`is meant to alert the operator to the Worn condition of the
`brake elements. The separate clips can become lost or
`dislodged during shipping, installation and/or use and add to
`the cost and complexity of manufacturing and installing
`such brake elements.
`
`SUMMARY OF THE INVENTION
`
`[0006] A brake element constructed according to the
`present invention comprises a backing plate having a front
`surface on Which a pad of friction material is secured. The
`pad has an outer braking surface that is spaced from the front
`surface of the backing plate and is adapted to frictionally
`engage a rotating brake rotor in use. AWear sensor is formed
`as one piece With the backing plate and projects outWardly
`of the front surface toWard but terminating short of the
`braking surface of the pad. When the pad Wears, the integral
`sensor is eXposed and rubs on the rotating brake rotor to
`signal a Worn condition of the pad.
`
`[0007] The invention has the advantage of eliminating
`parts by incorporating the Wear sensor as an integral part of
`the backing plate.
`[0008] The one piece construction of the backing plate and
`Wear sensor further simpli?es the manufacture of such brake
`elements since the steps of procuring, stocking, supplying
`and assembly an otherWise separate Wear sensor clip is
`eliminated.
`
`[0009] The one piece Wear sensor construction has the
`further advantage of enabling precise positioning of the Wear
`sensor tip end relative to the front face of the backing plate,
`and thus the depth of pad Wear permitted before the Wear
`sensor is eXposed. This has the advantage of getting the most
`use out of the pads and having consistency from pad to pad.
`
`[0010] The structure is much simpler since there is no
`need to fabricate a clip that has both Wear sensor features
`and mounting features. According to a preferred embodi
`ment, all that may be needed is a punch for displacing a
`portion of the backing plate out of the plane of the backing
`plate to yield a tab-like Wear sensor projection.
`
`[0011] The one-piece construction has the further advan
`tage of offering the manufacturer the ?exibility of either
`forming the Wear sensor feature adjacent to the pad (such
`that it can be formed before or after the pad is secured to the
`backing plate) or positioned to be embedded or embodied in
`
`THE DRAWINGS
`
`[0012] These and other features and advantages of the
`present invention Will become more readily appreciated
`When considered in connection With the folloWing detailed
`description and appended draWings, Wherein:
`
`[0013] FIG. 1 is a front elevation vieW of a brake pad
`made according to a ?st embodiment of the invention;
`
`[0014] FIG. 2 is an enlarged fragmentary sectional vieW
`taken generally along lines 202 of FIG. 1; and
`
`[0015] FIG. 3 is a vieW like FIG. 2, but of an alternative
`embodiment.
`
`DETAILED DESCRIPTION
`
`[0016] Disclosed in FIGS. 1 and 2 is a brake element 10
`constructed according to a ?rst embodiment of the invention
`having a steel backing plate 12 With a back surface 14 and
`a front surface 16. A pad 18 of friction material is mounted
`on the front surface 16. The pad 18 has a predetermined
`thickness betWeen an outer braking surface 20 and in inner
`mounting surface 22 or the front surface 16.
`
`[0017] The backing plate 12 is formed With an integrated
`Wear sensor 24. The Wear sensor 24 projects outWardly from
`the front surface 16 of the back plate 12 generally toWards
`the outer braking surface 20 of the pad 18. The Wear sensor
`24 terminates at a tip end 26 spaced betWeen the outer
`braking surface 20 and the mounting surface 22. According
`to the ?rst embodiment, the Wear sensor 24 is positioned
`adjacent to rather than embedded in, the friction pad 18. The
`Wear sensor 24 is preferably punched as a tab from the body
`of the backing plate 12. The tab 24 may be formed prior to
`or after the friction pad 18 has been mounted on the backing
`plate 12. As shoWn best in FIG. 2, the tab 24 remains
`attached at its base end to the body of the backing plate 12
`from Which it Was formed and thus remains as one piece
`With the backing plate 12.
`
`[0018] The tip end 26 of Wear sensor 24 represents a
`maXimum Wear condition of the pad 18. In operation, as the
`friction pad 18 Wears through use from braking engagement
`With a rotating metallic brake rotor (not shoWn) or the like,
`the thickness of the friction pad 18 diminishes. Once the pad
`18 Wears to the point Where the braking surface 20 is even
`(i.e., co-planar) With the tip end 26 of the Wear sensor 24, the
`Wear sensor 24 is caused to make the direct rubbing contact
`With the brake rotor (not shoWn). This rubbing contact
`generates an audible signal to the operator of the vehicle that
`the pad 18 has Worn to a condition near to the maXimum
`useful operating life of the brake pad 18, indicating the need
`for replacement of the brake element 10.
`
`[0019] FIG. 3 illustrates an alternative embodiment of the
`invention, Wherein the same reference numerals are used to
`represent like features With the ?st embodiment of FIGS. 1
`and 2, but are primed.
`[0020] Everything With the second embodiment of the
`brake element 10‘ is the same as that of the ?rst embodiment
`eXcept for the location of the Wear sensor 24‘. Whereas in the
`?rst embodiment the Wear sensor 24 Was formed adjacent to
`the brake pad 18, the Wear sensor 24‘ of the second embodi
`
`Page 3 of 4
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`

`

`US 2005/0173203 A1
`
`Aug. 11, 2005
`
`ment is embedded in the friction pad. The embedding can be
`achieved by forming the Wear tab ?rst and then forming the
`brake pad 18‘ on the backing plate 12‘ so that the tab 18‘
`becomes intimately surrounded by and indirect contact With
`the tab 24‘, or the brake pad 18‘ can be preformed With a
`cavity 28 on its inner mounting surface 22‘ and positioned to
`receive the tab 24‘ therein When the brake pad 18‘ is mounted
`to the backing plate 12‘. With the use of the cavity 28, the
`Wear tab 24‘ can be optionally formed in the backing plate
`12‘ before the pad 18‘ is applied.
`[0021] Obviously, many modi?cations and variations of
`the present invention are possible in light of the above
`teachings. It is, therefore, to be understood that Within the
`scope of the appended claims, the invention may be prac
`ticed otherWise than as speci?cally described.
`
`What is claimed is:
`1. A brake element for frictionally engaging a rotating
`brake rotor, comprising:
`a backing plate having a front surface;
`
`a pad of friction material secured to said front surface of
`said backing plate, said pad having an outer braking
`surface spaced from said front surface; and
`
`a Wear sensor formed as one piece With the backing plate
`and projecting outWardly of said front surface generally
`toWard but terminating short of said outer braking
`surface of said pad and operative When said pad Wears
`to the extent of exposing said Wear sensor to rubbing
`contact With the brake rotor to generate an audible
`signal indicating a Worn condition of said pad.
`2. The brake element of claim 1 Wherein said Wear sensor
`comprises a tab of material punched from and bent out
`Wardly of said backing plate.
`3. The brake element of claim 2 Wherein said tab is
`connected at a base to said backing plate.
`
`4. The brake element of claim 2 Wherein said tab is spaced
`from said pad.
`5. The brake element of claim 2 Wherein said tab is
`embedded in said pad.
`6. The brake element of claim 2 Wherein said backing
`plate is fabricated of steel.
`7. The brake element of claim 1 Wherein said Wear sensor
`has a tip end spaced betWeen said outer braking surface of
`said pad and said front surface of said backing plate.
`8. A method of making a brake element for frictionally
`engaging a rotating metallic brake rotor, said method com
`prising:
`
`preparing a backing plate having a front surface;
`
`securing a pad of friction material to the front surface of
`the backing plate, the pad having an outer braking
`surface spaced from the front surface; and
`
`forming a Wear sensor as one piece With the backing plate
`and projecting the Wear sensor outWardly of the front
`surface and generally toWard but terminating short of
`the outer braking surface of the pad and operative When
`the pad Wears to the eXtent of eXposing the Wear sensor
`to rubbing contact With the brake rotor to generate an
`audible signal indicating a Worn condition of the pad.
`9. The method of claim 8 Wherein the Wear sensor is
`formed by punching an attached tab of material from the
`backing plate and bending it outWardly of the front surface
`of the backing plate.
`10. The method of claim 9 Wherein the tab is formed in
`spaced relation to the friction pad.
`11. The method of claim 8 Wherein the Wear sensor is
`formed to be embedded in the friction pad.
`
`Page 4 of 4
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