Noise Dampening Brake Shoe for a Drum Brake

Abstract

A brake shoe for a drum brake includes a brake table and one or more webs supporting the brake table. One end of each web is pivotally coupled to an associated brake spider and another end of each web responds to a force applied by an actuator that causes the brake shoe to move between positions of engagement and disengagement with an associated braking surface. The brake shoe further includes means for damping movement of the brake shoe, during engagement of the brake shoe with the braking surface, for a natural frequency of the brake shoe having an order of at least two and a causing a bending modal shape of the brake shoe. In one embodiment, the damping means includes a damping plate disposed on one side of a web. A spring acts on a side of the plate opposite the web to urge the plate towards the web.

What is claimed is: 
     
         1 . A brake shoe for a drum brake, comprising:
 a brake table;   a first web supporting the brake table and having first and second ends, the first end configured for pivotally coupling to an associated brake spider of the drum brake and the second end configured to respond to a force applied by an actuator that causes the brake shoe to move between positions of engagement and disengagement with an associated braking surface;   a first damping plate disposed on a first side of the first web, the first damping plate including a first side facing the first side of the first web and a second side opposite the first side of the first damping plate;   a first fastener coupling the first damping plate to the first web, the first fastener defining a shank extending through a first set of aligned bores in the first damping plate and first web; and,   a first spring supported on the first fastener and disposed on the second side of the first damping plate and urging the first damping plate towards the first web.   
     
     
         2 . The brake shoe of  claim 1  wherein the first fastener includes a groove and the first spring is configured to be received within the groove. 
     
     
         3 . The brake shoe of  claim 1  wherein the first fastener includes a head disposed at one end of the shank on the first side of the first web and the first spring is disposed between the head of the first fastener and the second side of the first damping plate. 
     
     
         4 . The brake shoe of  claim 1  wherein the first damping plate is a unitary body. 
     
     
         5 . The brake shoe of  claim 1  wherein the first damping plate has a length that is at least seventy percent of a length of the first web. 
     
     
         6 . The brake shoe of  claim 1 , further comprising:
 a second fastener coupling the first damping plate to the first web, the second fastener defining a shank extending through a second set of aligned bores in the first damping plate and first web; and,   a second spring supported on the second fastener and disposed on the second side of the first damping plate and urging the first damping plate towards the first web.   
     
     
         7 . The brake shoe of  claim 1 , further comprising:
 a second web spaced from the first web and supporting the brake table, the second web having first and second ends, the first end of the second web configured for pivotally coupling to the associated brake spider of the drum brake and the second end of the second web configured to respond to the force applied by the actuator that causes the brake shoe to move between positions of engagement and disengagement with the associated braking surface;   a second damping plate disposed on a first side of the second web, the second damping plate including a first side facing the first side of the second web and a second side opposite the first side of the second damping plate;   a second fastener coupling the second damping plate to the second web, the second fastener defining a shank extending through a second set of aligned bores in the second damping plate and second web; and, a second spring supported on the second fastener and disposed on the second side of the second damping plate and urging the second damping plate towards the second web.   
     
     
         8 . The brake shoe of  claim 7  wherein the first sides of the first and second webs comprise inboard sides of the first and second webs. 
     
     
         9 . The brake shoe of  claim 1  wherein the first spring comprises a compression spring. 
     
     
         10 . The brake shoe of  claim 9  wherein the compression spring comprises a conical spring washer. 
     
     
         11 . The brake shoe of  claim 1  wherein the first damping plate is configured to, during engagement of the brake shoe with the associated braking surface, dampen movement of the brake shoe for at least one natural frequency of the brake shoe having an order of at least two and causing a bending modal shape of the brake shoe. 
     
     
         12 . A brake shoe for a drum brake, comprising:
 a brake table;   first and second webs supporting the brake table and spaced from one another, each of the first and second webs having first and second ends, the first end of each of the first and second webs configured for pivotally coupling to an associated brake spider of the drum brake and the second end of each of the first and second webs configured to respond to a force applied by an actuator that causes the brake shoe to move between positions of engagement and disengagement with an associated braking surface;   a first damping plate disposed on an inboard side of the first web;   a second damping plate disposed on an inboard side of the second web;   at least one fastener coupling the first damping plate to the first web and the second plate to the second web; and,   a first spring disposed about the at least one fastener between the first and second damping plates.   
     
     
         13 . The brake shoe of  claim 12 , wherein the at least one fastener comprises a first fastener extending through a first set of aligned bores in the first web and the first damping plate and a second fastener extending through a second set of aligned bores in the second web and the second damping plate, the first spring disposed about the first and second fasteners. 
     
     
         14 . The brake shoe of  claim 12 , further comprising:
 at least one additional fastener coupling the first damping plate to the first web and the second plate to the second web; and,   a second spring disposed about the at least one additional fastener between the first and second damping plates.   
     
     
         15 . The brake shoe of  claim 12  wherein the first damping plate is a unitary body. 
     
     
         16 . The brake shoe of  claim 12  wherein the first damping plate has a length that is at least seventy percent of a length of the first web and the second damping plate has a length that is at least seventy percent of a length of the second web. 
     
     
         17 . The brake shoe of  claim 12  wherein the first spring comprises a compression spring. 
     
     
         18 . The brake shoe of  claim 12  wherein the first and second damping plates are configure to, during engagement of the brake shoe with the associated braking surface, dampen movement of the brake shoe for at least one natural frequency of the brake shoe having an order of at least two and causing a bending modal shape of the brake shoe. 
     
     
         19 . A brake shoe for a drum brake, comprising:
 a brake table;   a first web supporting the brake table and having first and second ends, the first end configured for pivotally coupling to an associated brake spider of the drum brake and the second end configured to respond to a force applied by an actuator that causes the brake shoe to move between positions of engagement and disengagement with an associated braking surface; and,   a first damping plate disposed on a first side of the first web and coupled to the first web   wherein the first damping plate is configured to, during engagement of the brake shoe with the associate braking surface, dampen movement of the brake shoe for a natural frequency of the brake shoe having an order of at least two and a causing a bending modal shape of the brake shoe.   
     
     
         20 . The brake shoe of  claim 19  wherein the first damping plate includes a first side facing the first side of the first web and a second side opposite the first side of the first damping plate and further comprising:
 a plurality of fasteners coupling the first damping plate to the first web, each of the plurality of fasteners defining a shank extending through a corresponding set of aligned bores in the first damping plate and first web; and, 
 a plurality of springs, each of the plurality of springs supported on one of the plurality of fasteners and disposed on the second side of the first damping plate and urging the first damping plate towards the first web. 
 
     
     
         21 . The brake shoe of  claim 20  wherein each of the plurality of fasteners includes a groove configured to receive a corresponding one of the plurality of springs. 
     
     
         22 . The brake shoe of  claim 20  wherein each of the plurality of fasteners includes a head disposed at one end of the shank on the first side of the first web and a corresponding spring of the plurality of springs is disposed between the head and the second side of the damping plate. 
     
     
         23 . The brake shoe of  claim 19  wherein the first damping plate is a unitary body. 
     
     
         24 . The brake shoe of  claim 19  wherein the first damping plate has a length that is at least seventy percent of a length of the first web. 
     
     
         25 . The brake shoe of  claim 19 , further comprising:
 a second web spaced from the first web and supporting the brake table, the second web having first and second ends, the first end of the second web configured for pivotally coupling to the associated brake spider of the drum brake and the second end of the second web configured to respond to the force applied by the actuator that causes the brake shoe to move between positions of engagement and disengagement with the associated braking surface; and,   a second damping plate disposed on a first side of the second web.   
     
     
         26 . The brake shoe of  claim 25  wherein the first sides of the first and second webs comprise inboard sides of the first and second webs. 
     
     
         27 . The brake shoe of  claim 26 , further comprising:
 at least one fastener coupling the first damping plate to the first web and the second damping plate to the second web; and,   a first spring disposed about the at least one fastener between the first and second damping plates.   
     
     
         28 . A brake shoe for a drum brake, comprising:
 a brake table;   a first web supporting the brake table and having first and second ends, the first end configured for pivotally coupling to an associated brake spider of the drum brake and the second end configured to respond to a force applied by an actuator that causes the brake shoe to move between positions of engagement and disengagement with an associated braking surface; and,   means for damping movement of the brake shoe, during engagement of the brake shoe with the associated braking surface, for a natural frequency of the brake shoe having an order of at least two and a causing a bending modal shape of the brake shoe.   
     
     
         29 . The brake shoe of  claim 28  wherein the damping means includes a first damping plate disposed on a first side of the first web and further comprising means for coupling the first damping plate to the first web.