Brake lining wear sensing circuit

Claim 2

Vehicle brake apparatus comprising, in combination, at least one brake assembly including a brake shoe, a brake lining affixed to the brake shoe, and an electrically grounded brake drum positioned for frictional cooperation with the brake lining effective to brake the vehicle, detection means for detecting excessive wear of the brake lining including first and second terminals, a conductive wire having at least one loop formed therein connected between the terminals, and a grounded indicator network including a power source and an indicator device connected to the first terminal so as to energize the indicator device when the wire is grounded, attachment means for securing the wire loop to the brake shoe in proximity to the brake lining, the attachment means including means for supporting the loop relative to the brake shoe at a predetermined level below which brake lining wear is excessive, thereby enabling the brake drum to contact and ground the wire when the brake lining is excessively worn and the vehicle is braked so as to energize the indicator device and indicate the worn condition of the brake lining, and selectively operable switch means connected between the second terminal and ground for checking the operativeness of the detection means by selectively grounding the second terminal, thereby selectively energizing the indicator device when the detection means is operative.

Claim 3

Vehicle brake apparatus comprising, in combination, at least one brake assembly including a brake shoe, a brake lining affixed to the brake shoe, and an electrically grounded brake drum positioned for frictional cooperation with the brake lining effective to brake the vehicle, detection means for detecting excessive wear of the brake lining including first and second terminals, a conductive wire having at least one loop formed therein connected between the terminals, and a grounded indicator network including a power source and an indicator device connected to the first terminal so as to energize the indicator device when the wire is grounded, a clip for attaching the wire loop to the brake shoe in proximity to the brake lining, the clip including first and second plates spaced apart, a third plate connecting the first and second plates so as to form a unit having an open side opposed to the third plate for receiving an edge of the brake shoe, the unit being positioned on the brake shoe by inserting the edge of the brake shoe through the open side, means for securing the clip to the brake shoe so as to prevent relative movement therebetween, supporting means for supporting the wire loop at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, thereby enabling the brake drum to contact and ground the wire loop when the brake lining is worn excessively and the vehicle is braked so as to energize the indicator device and indicate the worn condition of the brake lining, and means for securing the wire loop to the supporting means so as to prevent relative movement between the wire loop and the clip, and selectively operable switch means connected between the secoNd terminal and ground for checking the operativeness of the detection means by selectively grounding the second terminal, thereby selectively energizing the indicator device when the detection means is operative.

Claim 4

Vehicle brake apparatus comprising, in combination, at least one brake assembly including a brake shoe, a brake lining affixed to the brake shoe, and an electrically grounded brake drum positioned for frictional cooperation with the brake lining effective to brake the vehicle, detection means for detecting excessive wear of the brake lining including first and second terminals, a conductive wire having at least one loop formed therein connected between the terminals, and a grounded indicator network including a power source and an indicator device connected to the first terminal so as to energize the indicator device when the wire is grounded, a clip for attaching the wire loop to the brake shoe in proximity to the brake lining, the clip including first and second plates spaced apart, a third plate connecting the first and second plates so as to form a unit having an open side opposed to the third plate for receiving an edge of the brake shoe, the unit being positioned on the brake shoe by inserting the edge of the brake shoe through the open side, means for securing the clip to the brake shoe so as to prevent relative movement therebetween, supporting means for supporting the wire loop at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, thereby enabling the brake drum to contact and ground the wire loop when the brake lining is worn excessively and the vehicle is braked so as to energize the indicator device and indicate the worn condition of the brake lining, and means for securing the wire loop to the supporting means so as to prevent relative movement between the wire loop and the clip, and selectively operable switch means connected between the secoNd terminal and ground for checking the operativeness of the detection means by selectively grounding the second terminal, thereby selectively energizing the indicator device when the detection means is operative.

Claim 5

Vehicle brake apparatus comprising, in combination, at least one brake assembly including a brake shoe, a brake lining affixed to the brake shoe, and an electrically grounded brake drum positioned for frictional cooperation with the brake lining effective to brake the vehicle, detection means for detecting excessive wear of the brake lining including first and second terminals, a conductive wire having at least one loop formed therein connected between the terminals, and a grounded indicator network including a power source and an indicator device connected to the first terminal so as to energize the indicator device when the wire is grounded, a clip for attaching the wire loop to the brake shoe in proximity to the brake lining, the clip including first and second plates spaced apart, a third plate connecting the first and second plates so as to form a unit having an open side opposed to the third plate for receiving an edge of the brake shoe, the unit being positioned on the brake shoe by inserting the edge of the brake shoe through the open side, at least one projection formed in the second plate for engaging the brake shoe so as to prevent relative movement between the brake shoe and the clip, a wire loop supporting member formed in the first plate for supporting the wire loop at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, thereby enabling the brake drum to contact and ground the wire loop when the brake lining is worn excessively and the vehicle is braked so as to energize the indicator device and indicate the worn condition of the brake lining, the wire loop enclosing the supporting member, and extending between the first plate and the brake shoe, the wire being held therebetween by frictional forces so as to prevent movement of the wire loop relative to the clip, and selectively operable switch means connected between the second terminal and ground for checking the operativeness of the detection means by selectively grounding the second terminal, thereby selectively energizing the indicator device when the detection means is operative.

Claim 6

Vehicle brake apparatus comprising, in combination, at least one brake assembly including a brake shoe, a brake lining affixed to the brake shoe, and an electrically grounded brake drum positioned for frictional cooperation with the brake lining effective to brake the vehicle, detection means for detecting excessive wear of the brake lining including first and second terminals, a conductive wire having at least one loop formed therein connected between the terminals, and a grounded indicator network including a power source and an indicator device connected to the first terminal so as to energize the indicator device when the wire is grounded, a clip for attaching the wire loop to the brake shoe in proximity to the brake lining, the clip including first and second plates spaced apart, a third plate connecting the first and second plates so as to form a unit having an open side opposed to the third plate for receiving an edge of the brake shoe, the unit being positioned on the brake shoe by inserting the edge of the brake shoe through the open side, at least one projection formed in the second plate for engaging the brake shoe so as to prevent relative movement between the brake shoe and the clip, a wire loop supporting member formed in the first plate for supporting the wire loop at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, thereby enabling the brake drum to contact and ground the wire loop when the brake lining is worn excessively and the vehicle is braked so as to energize the indicator device and indicate the worn condition of the brake lining, the wire loop enclosing the supporting member, and extending between the first plate and the brake shoe, the wire being held therebetween by frictional forces so as to prevent movement of the wire loop relative to the clip, and selectively operable switch means connected between the second terminal and ground for checking the operativeness of the detection means by selectively grounding the second terminal, thereby selectively energizing the indicator device when the detection means is operative.

Claim 7

Vehicle brake apparatus comprising, in combination, a brake assembly including an electrically grounded brake drum and a brake shoe assembly having a brake lining and a brake shoe for supporting the brake lining and moving the brake lining into frictional engagement with the brake drum effective to brake the vehicle, means for indicating excessive wear of the brake lining including a conductive sensor and an indicator network having an indicator device and a power source connected to the sensor so as to energize the indicator device with the power source when the sensor is grounded, and a clip for attaching the sensor to the brake shoe so as to position the sensor proximate the brake lining and at a predetermined level above the brake shoe, the clip including a channel unit adapted for insertion of the brake shoe therein, the channel unit having one side formed by a first flange having an embossment externally directed relative to the channel unit for supporting the sensor at the predetermined level above the brake shoe and another side formed by a second flange having at least one embossment internally directed relative to the channel unit for engaging the brake shoe so as to prevent relative movement between the clip and the brake shoe, and means for securing the sensor to the externally directed embossment whereby the sensor is contacted and grounded by the brake drum when the vehicle is braked and the brake lining is worn below the predetermined level, below which level brake lining wear is deemed excessive, thereby indicating when the brake lining is excessively worn.

Claim 8

Vehicle brake apparatus comprising, in combination, a brake assembly including an electrically grounded brake drum and a brake shoe assembly having a brake lining and a brake shoe for supporting the brake lining and moving the brake lining into frictional engagement with the brake drum effective to brake the vehicle, means for indicating excessive wear of the brake lining including a conductive sensor and an indicator network having an indicator device and a power source connected to the sensor so as to energize the indicator device with the power source when the sensor is grounded, and a clip for attaching the sensor to the brake shoe so as to position the sensor proximate the brake lining and at a predetermined level above the brake shoe, the clip including a channel unit adapted for insertion of the brake shoe therein, the channel unit having one side formed by a first flange having an embossment externally directed relative to the channel unit for supporting the sensor at the predetermined level above the brake shoe and another side formed by a second flange having at least one embossment internally directed relative to the channel unit for engaging the brake shoe so as to prevent relative movement between the clip and the brake shoe, and means for securing the sensor to the externally directed embossment whereby the sensor is contacted and grounded by the brake drum when the vehicle is braked and the brake lining is worn below the predetermined level, below which level brake lining wear is deemed excessive, thereby indicating when the brake lining is excessively worn.

Claim 9

In a vehicle brake system having a plurality of brake shoes, brake linings supporteD by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, a plurality of series connected conductive sensors, means for attaching the sensors to the brake shoes proximate the brake linings, the means including sensor positioning means for supporting the sensors at a predetermined level relative to the brake shoes so as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensors in proximity to the brake drums, thereby enabling a brake drum to contact and ground a sensor when the brake lining associated therewith is excessively worn and the vehicle is braked, indicating means responsive to the potential of the sensors for indicating when one or more of the sensors are grounded, and selectively operable switch means connected in series circuit between the sensors and ground for checking the operativeness of the sensors and the indicating means by temporarily grounding the sensors.

Claim 10

In a vehicle brake system having a plurality of brake shoes, brake linings supporteD by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, a plurality of series connected conductive sensors, means for attaching the sensors to the brake shoes proximate the brake linings, the means including sensor positioning means for supporting the sensors at a predetermined level relative to the brake shoes so as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensors in proximity to the brake drums, thereby enabling a brake drum to contact and ground a sensor when the brake lining associated therewith is excessively worn and the vehicle is braked, indicating means responsive to the potential of the sensors for indicating when one or more of the sensors are grounded, and selectively operable switch means connected in series circuit between the sensors and ground for checking the operativeness of the sensors and the indicating means by temporarily grounding the sensors.

Claim 11

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, first and second conductive terminals, a plurality of conductive sensors series connected between the terminals, means for attaching the sensors to the brake shoes proximate the brake linings, the means including sensor positioning means for supporting each of the sensors at a predetermined level relative to the brake shoe associated therewith so as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensors adjacent a brake drum so as to enable the brake drum to contact and ground a sensor when the brake lining associated therewith is excessively worn and the vehicle is braked, an indicator network including a power source and an indicator device series connected between ground and the first terminal so as to effect energization of the indicator device by the power source when one or more of the sensors are grounded, thereby indicating that a brake lining is excessively worn, and selectively operable switch means series connected between ground and the second terminal for checking the operativeness of the indicator network and the sensors by temporarily grounding the second terminal, thereby temporarily effecting energization of the indicator device through the sensors when the indicator network and the sensors are operable.

Claim 12

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, first and second conductive terminals, a plurality of conductive sensors series connected between the terminals, means for attaching the sensors to the brake shoes proximate the brake linings, the means including sensor positioning means for supporting each of the sensors at a predetermined level relative to the brake shoe associated therewith so as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensors adjacent a brake drum so as to enable the brake drum to contact and ground a sensor when the brake lining associated therewith is excessively worn and the vehicle is braked, an indicator network including a power source and an indicator device series connected between ground and the first terminal so as to effect energization of the indicator device by the power source when one or more of the sensors are grounded, thereby indicating that a brake lining is excessively worn, and selectively operable switch means series connected between ground and the second terminal for checking the operativeness of the indicator network and the sensors by temporarily grounding the second terminal, thereby temporarily effecting energization of the indicator device through the sensors when the indicator network and the sensors are operable.

Claim 13

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, a plurality of series connected conductive wire loop sensors, a plurality of clips for attaching each of the sensors to the brake shoes proximate the brake linings supported by the respective brake shoes, the clips each including first and second plates spaced apart, a third plate joined to the first and second plates to form a unit having an open side opposed to the third plate and adapted for receiving therein an edge of a brake shoe, the clip being placed on the brake shoe by insertion of the brake shoe edge into the unit through the open side, a sensor supporting member joined to the first plate for supporting a sensor proximate a brake lining secured to the brake shoe and at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, means for securing the clip to the brake shoe, and means for securing the sensor to the clip so as to prevent relative movement therebetween and to position the sensor in proximity to a brake drum, thereby enabling the brake drum to contact and ground the sensor when the brake lining associated therewith is excessively worn and tHe vehicle is braked, and indicator means responsive to the potential of the sensor for indicating when the sensor is grounded so as to indicate the worn condition of the brake lining.

Claim 14

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, a plurality of series connected conductive wire loop sensors, a plurality of clips for attaching each of the sensors to the brake shoes proximate the brake linings supported by the respective brake shoes, the clips each including first and second plates spaced apart, a third plate joined to the first and second plates to form a unit having an open side opposed to the third plate and adapted for receiving therein an edge of a brake shoe, the clip being placed on the brake shoe by insertion of the brake shoe edge into the unit through the open side, a sensor supporting member joined to the first plate for supporting a sensor proximate a brake lining secured to the brake shoe and at a predetermined level above the brake shoe below which level brake lining wear is deemed excessive, means for securing the clip to the brake shoe, and means for securing the sensor to the clip so as to prevent relative movement therebetween and to position the sensor in proximity to a brake drum, thereby enabling the brake drum to contact and ground the sensor when the brake lining associated therewith is excessively worn and tHe vehicle is braked, and indicator means responsive to the potential of the sensor for indicating when the sensor is grounded so as to indicate the worn condition of the brake lining.

Claim 15

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, first and second conductive terminals, a plurality of conductive wire loop sensors series connected by a plurality of leads between the terminals, a plurality of clips for attaching the sensors to the brake shoes proximate the brake linings supported by the respective brake shoes, the clips each including first and second plates spaced apart, a third plate joined to the first and second plates so as to form a unit having an open side opposed to the third surface for receiving an edge of a brake shoe, the clip being attached to the brake shoe by insertion of the brake shoe edge through the open side of the unit, the first and third plates each having removed portions for the passage of leads therethrough to a sensor, a sensor supporting member joined to the first plate for supporting the sensor proximate a brake lining and at a predetermined level above the brake shoe as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensor adjacent a brake drum associated with the brake lining, thereby enabling the brake drum to contact and ground the sensor when the brake lining is excessively worn and the vehicle is braked, the sensor being positioned so as to loop the sensor supporting member, engagement means including at least one projection secured to the second plate for preventing relative movement between the clip and the brake shoe by engaging the brake shoe with the projection, and means for securing the sensor to the clip by frictionally restraining the leads to the sensor between the clip and the brake shoe, indicating means connected to the first terminal so as to be responsive to the potential of the sensor for indicating when the sensor is grounded, thereby indicating the worn condition of the brake lining, and selectively operable switch means series connected between the second terminal and ground for checking the operativeness of the indicating means and the sensors by selectively grounding the sensors.

Claim 16

In a vehicle brake system having a plurality of brake shoes, brake linings supported by the brake shoes, and electrically grounded brake drums frictionally cooperating with the brake linings to effect braking of the vehicle, the improvement comprising, in combination, first and second conductive terminals, a plurality of conductive wire loop sensors series connected by a plurality of leads between the terminals, a plurality of clips for attaching the sensors to the brake shoes proximate the brake linings supported by the respective brake shoes, the clips each including first and second plates spaced apart, a third plate joined to the first and second plates so as to form a unit having an open side opposed to the third surface for receiving an edge of a brake shoe, the clip being attached to the brake shoe by insertion of the brake shoe edge through the open side of the unit, the first and third plates each having removed portions for the passage of leads therethrough to a sensor, a sensor supporting member joined to the first plate for supporting the sensor proximate a brake lining and at a predetermined level above the brake shoe as to establish a reference level below which brake lining wear is deemed excessive and for positioning the sensor adjacent a brake drum associated with the brake lining, thereby enabling the brake drum to contact and ground the sensor when the brake lining is excessively worn and the vehicle is braked, the sensor being positioned so as to loop the sensor supporting member, engagement means including at least one projection secured to the second plate for preventing relative movement between the clip and the brake shoe by engaging the brake shoe with the projection, and means for securing the sensor to the clip by frictionally restraining the leads to the sensor between the clip and the brake shoe, indicating means connected to the first terminal so as to be responsive to the potential of the sensor for indicating when the sensor is grounded, thereby indicating the worn condition of the brake lining, and selectively operable switch means series connected between the second terminal and ground for checking the operativeness of the indicating means and the sensors by selectively grounding the sensors.