Brake shoe proximity sensor
A brake system with an integral proximity sensor for providing an indication of a condition of the brake system. The brake system includes a brake drum, a brake shoe, a brake pad, and a position sensor. The brake pad is connected to a pad mounting surface of the brake shoe. The brake pad and brake shoe are movable from a disengaged position, where the brake pad is spaced apart from the brake drum to an engaged position, where the pad is in forcible engagement with the brake drum. The position sensor is coupled to the brake shoe for sensing the position of the brake shoe with respect to the position sensor. The position of the brake shoe with respect to the position sensor provides an indication of one or more conditions of the brake system.
1. A brake system with an integral position sensor, comprising:
a) a brake drum having a cylindrical surface;
b) a brake shoe having a pad mounting surface;
c) a brake lining pad connected to said pad mounting surface of said shoe, said pad and shoe being concentric with said cylindrical surface, said shoe and pad being movable between a disengaged position wherein said pad is spaced apart from said cylindrical surface to an engaged position wherein said pad is in forcible engagement with said cylindrical surface;
d) an actuator coupled to the brake shoe for moving the shoe and an associated pad between the disengaged position and the engaged position; and
e) a position sensor mounted on a surface outside the brake drum such that said position sensor is shielded from heat and dust generated by said brake shoe and said brake drum, comprising a mechanical linkage that extends through an opening in said surface, said linkage includes a first end connected to said brake shoe and a second end connected to said sensor, wherein said position sensor is coupled directly to said brake shoe, said position sensor is arranged for sensing a change in position of the shoe relative to the position sensor when the brake shoe is moved between the disengaged and engaged positions and to thereby provide an indication of a condition of the brake system.
2. The brake system of claim 1 wherein said surface is oriented away from said brake shoe.
3. The brake system of claim 1 wherein said position sensor is a linear variable differential transformer.
4. The brake system of claim 1 wherein said position sensor is a potentiometric displacement transducer.
5. The brake system of claim 1 wherein said position sensor is aligned with the center of the brake shoe.
6. The brake system of claim 1 further comprising an insulation barrier disposed between said brake shoe and said position sensor.
7. The brake system of claim 1 wherein said brake shoe is pneumatically actuated.