Disc brake wear monitor system

Claim 2

A brake lining wear warning system comprising; a brake pad assembly having a lining backing plate and a lining secured thereto, said lining having a braking surface adapted to Frictionally engage a member to be braked, normally closed passage means in said lining having originally predetermined spacing from said braking surface equal to the predetermined amount of lining wear allowable after which said warning system is to be activated, said passage means being opened by lining wear beyond the allowable amount at any point wherein said passage means is positioned at the originally predetermined spacing, conduit means fluid connecting said passage means to vacuum switch and a vacuum source, an electrical circuit having therein said vacuum switch and a source of electrical energy and a warning indicator controlled by actuation of said vacuum switch to be energized when said vacuum switch is actuated in response to a less than predetermined minimum vacuum in said conduit means at said vacuum switch.

Claim 3

The brake lining wear warning system of claim 1, said passage means comprising at least one channel formed in the surface of said lining opposite said braking surface and closed by said lining backing plate.

Claim 4

The brake lining wear warning system of claim 2, said passage means further comprising a plurality of monitor ports formed as recesses extending further into said lining than said at least one channel and terminating at said originally predetermined spacing from said braking surface.

Claim 5

The brake lining wear warning system of claim 3, said monitor ports being positioned at leading and trailing and intermediate portions of said lining.

Claim 6

The brake lining wear warning system of claim 1, said conduit means further having an air filter therein fluidly intermediate said lining and said vacuum switch to prevent lining particles from passing to said vacuum switch and beyond.

Claim 7

The brake lining wear warning system of claim 1, said conduit means further having a metering orifice therein intermediate said vacuum switch and said vacuum source for insuring a minimum pressure differential between said vacuum source and said vacuum switch upon opening of said normally closed passage means.

Claim 8

The brake lining wear warning system of claim 1, said electrical circuit including a vehicle engine ignition switch and said vacuum source being the intake manifold of the vehicle engine whereby when said ignition switch is closed said warning indicator is energized until sufficient vacuum is generated to open said vacuum switch, thereby providing a test of said system.

Claim 9

A vehicle brake lining wear warning system comprising: a brake pad assembly including, a brake lining backing plate having a brake lining secured thereto, said lining having one surface engaging said backing plate and an opposite surface adapted to frictionally engage a member to be braked, channel passages found in said lining one surface in fluid intercommunication and extending into said lining toward said opposite surface and being closed from the ambient atmosphere by said backing plate, and a plurality of monitor ports formed in said lining as recesses in fluid communication with said channel passages and extending toward said opposite surface, the closed ends of said recesses being spaced from said opposite surface by a predetermined lining wear allowable thickness; a vacuum operated first switch having a normally closed position and opened by a predetermined vacuum impressed thereon, an electrical circuit having therein in series said vacuum switch, a source of electrical energy, a warning indicator, and a second switch normally closed during starting and running of the vehicle engine; a vacuum source comprising the intake manifold of the vehicle engine; and conduit means fluid connecting said channel passages and said first switch and said vacuum source; said warning indicator being energized when said second switch is closed and said first switch has insufficient vacuum imposed thereon to be opened, said channel passages and said conduit means and said first switch being subjected to substantially atMospheric pressure and therefore insufficient vacuum to open said first switch when said lining is worn to open at least one of said monitor ports to atmosphere as well as when the vehicle engine is not operating and no vacuum is being produced in said intake manifold.

Claim 10

A vehicle brake lining wear warning system comprising: a brake pad assembly including, a brake lining backing plate having a brake lining secured thereto, said lining having one surface engaging said backing plate and an opposite surface adapted to frictionally engage a member to be braked, channel passages found in said lining one surface in fluid intercommunication and extending into said lining toward said opposite surface and being closed from the ambient atmosphere by said backing plate, and a plurality of monitor ports formed in said lining as recesses in fluid communication with said channel passages and extending toward said opposite surface, the closed ends of said recesses being spaced from said opposite surface by a predetermined lining wear allowable thickness; a vacuum operated first switch having a normally closed position and opened by a predetermined vacuum impressed thereon, an electrical circuit having therein in series said vacuum switch, a source of electrical energy, a warning indicator, and a second switch normally closed during starting and running of the vehicle engine; a vacuum source comprising the intake manifold of the vehicle engine; and conduit means fluid connecting said channel passages and said first switch and said vacuum source; said warning indicator being energized when said second switch is closed and said first switch has insufficient vacuum imposed thereon to be opened, said channel passages and said conduit means and said first switch being subjected to substantially atMospheric pressure and therefore insufficient vacuum to open said first switch when said lining is worn to open at least one of said monitor ports to atmosphere as well as when the vehicle engine is not operating and no vacuum is being produced in said intake manifold.