Disk brake rotor with visual wear indicator

{
  "publication_number": "US6457566B1",
  "country": "US",
  "kind": "B1",
  "title": "Disk brake rotor with visual wear indicator",
  "abstract": "A brake rotor for a vehicle is provided with one or more visual wear indicators on brake contact surfaces to allow easy visual inspection of brake rotor condition without the need for measurement tools. The inventive visual wear indicator system is not obtrusive and as such removes only a relatively small amount of brake contact surface to form a recessed surface at a depth of a predetermined minimum useable rotor thickness. With this inventive rotor, one can visually inspect the condition of a brake rotor and readily determine whether the rotor requires replacement or remachining. The visual wear indicator is provided on a brake contact surface of the rotor solely within a brake contact region so as to provide an accurate reflection of the condition of the rotor in areas where wear will occur. The visual indicator may be provided on only one, but preferably both, sides of the rotor and may take numerous forms, such as a cylindrical bore, a more complex shape, an annular groove or even an eccentric groove. For additional visibility, the visual wear indicator may be colored for additional contrast. The visual wear indicator may also be coated to prevent rusting.",
  "claims": [
    "1. A brake rotor for a vehicle brake system, comprising: a central hub rotatably mountable to a vehicle for rotation about an axis; and at least one radially extending annular disk extending radially from the central hub, the at least one annular disk including inboard and outboard planar brake contact surfaces, at least one visual wear indicator formed as a depression in at least one of said inboard and outboard brake contact surfaces located at a portion of the brake rotor intermediate the central hub and a radial extremity solely within a brake contact region, the visual wear indicator including a recessed surface substantially parallel to the brake contact surface at a depth such that the thickness of the annular disk below the recessed surface corresponds to or is greater than a predetermined minimum useable thickness of the annular disk.",
    "2. The brake rotor of claim 1, wherein the at least one wear indicator is provided on both of the inboard and outboard brake contact surfaces.",
    "3. The brake rotor of claim 2, wherein the visual wear indicator on the inboard brake contact surface is substantially diametrically opposed to the visual wear indicator on the outboard brake contact surface.",
    "4. The brake rotor of claim 1, wherein at least a bottom surface of the visual wear indicator parallel with the planar brake contact surface is coated to protect the indicator from rusting or other environmental degradation.",
    "5. The brake rotor of claim 1, wherein the at least one wear indicator is a cylindrical counterbore.",
    "6. The brake rotor of claim 1, wherein the at least one wear indicator has a complex shape that is dimensionally smaller than a brake pad surface area.",
    "7. The brake rotor of claim 1, wherein the at least one visual wear indicator is in the form of a recessed annular groove that is substantially concentric with the axis of rotation of the rotor.",
    "8. The brake rotor of claim 1, wherein the at least one visual wear indicator is in the form of an eccentric groove substantially concentric with the rotor axis.",
    "9. The brake rotor of claim 1, wherein at least a bottom surface of the visual wear indicator parallel with the planar brake contact surface is of a color that contrasts with a color of the remaining brake contact surface to enhance visibility of the wear indicator.",
    "10. A method of forming a visual wear indicator on a brake rotor, comprising the steps of:` forming a brake rotor with a central hub rotatably mountable to a vehicle and at least one radially extending annular disk extending radially from the central hub, the at least one annular disk including inboard and outboard planar brake contact surfaces rotatable about an axis of rotation; and forming at least one visual wear indicator as a depression on at least one of said inboard and outboard brake contact surfaces located at a portion of the brake rotor intermediate the central hub and a radial extremity solely within a brake contact region of the brake contact surfaces that will be worn due to brake pad contact during use, the visual wear indicator including a recessed surface substantially parallel to the brake contact surfaces at a depth such that the thickness of the annular disk below the recessed surface corresponds to or is greater than a predetermined minimum useable thickness of the annular disk.",
    "11. The method of claim 10, further comprising a step of coating at least a bottom surface of the at least one visual wear indicator to protect the indicator from environmental degradation.",
    "12. The method of claim 10, further comprising a step of coloring the at least one visual wear indicator a color that contrasts with a color of the remaining brake contact surface to enhance visibility of the wear indicator.",
    "13. The method of claim 10, wherein the step of forming the at least one visual wear indicator forms the at least one wear indicator on both of the inboard and outboard breake contact surfaces.",
    "14. The method of claim 13, wherein the step of forming the at least one visual wear indicator forms the visual wear indicator on the inboard brake contact surface to be substantially diametrically opposed to the visual wear indicator on the outboard brake contact surface.",
    "15. The method of claim 10, wherein the step of forming the at least one visual wear indicator forms the depression in the shape of a cylindrical bore.",
    "16. The method of claim 10, wherein the step of forming forms the depression to have a complex shape that is dimensionally smaller than a brake pad surface area.",
    "17. The method of claim 10, wherein the step of forming the depression forms the at least one visual wear indicator in the form of an annular groove that is substantially concentric with the axis of rotation of the rotor.",
    "18. The method of claim 10, wherein the step of forming the depression forms the at least one visual wear indicator in the form of an eccentric groove substantiallY concentric with the rotor axis."
  ],
  "description_excerpt": "1. Field of Invention\n\nThe invention relates to a disk brake rotor with a wear indicator that does not adversely affect operation of the rotor yet allows easy visual inspection of wear.\n\n2. Description of Related Art\n\nConventional disk brake rotors generally include a pair of mutually spaced-apart annular disks that form two opposed planar brake contact surfaces. These opposed brake contact surfaces receive braking force as applied by a brake caliper through two opposed brake pads. These rotors encounter frictional forces and heat build up each and every time the brakes are applied. Over time, these rotors (as well as the pads) wear or are damaged due to heat degradation and material fatigue caused by the cyclical application of frictional brake forces. Eventually, both the brake pads and the brake rotors become worn to a point where replacement is warranted or necessary. The full life expectancy of these brake pads and rotors cannot be determined with precision in advance as it is dependent upon many variables. In view of this, most vehicle manufacturers and brake component manufacturing companies recommend periodic inspection of brake components.\n\nFor inspection or indication purposes, brake pads routinely include metal wear indicators located to one side of the brake pad. These indicators extend along a thickness of the brake pad by a distance corresponding to a predetermined minimum wear depth. Even if the brake pads are not completely worn out, visual inspection of the brake pads can be easily performed by viewing these indicators and ascertaining whether the pads are worn sufficiently to warrant replacement.",
  "cpc": [
    "F16D 66/02",
    "F16D 2065/1328",
    "F16D 2069/004",
    "F16D 65/12"
  ],
  "ipc": [
    "F16D 65/12"
  ],
  "assignees": [
    "Brake Parts Inc LLC"
  ],
  "inventors": [
    "Dennis E. Toby"
  ],
  "filing_date": "2001-02-26",
  "publication_date": "2002-10-01",
  "grant_date": "2002-10-01",
  "priority_date": "2001-02-26",
  "application_number": "US-79157001-A",
  "family_id": "25154125",
  "cited_by_count": 64,
  "citations": [
    "US1949670A",
    "US2398006A",
    "US3587416A",
    "US4049084A",
    "US4143744A",
    "US5662192A",
    "USD413093S",
    "US6279698B1"
  ]
}