Brake assembly wear detector

• US 3,986,164 A
• Filed: 08/26/1974
• Issued: 10/12/1976
• Est. Priority Date: 08/29/1973
• Status: Expired due to Term

• Current Assignee: Sumitomo Denki Kogyo Kabushiki Kaisha (Sumitomo Corporation), Toyota Jidosha Kogyo Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Sumitomo Denki Kogyo Kabushiki Kaisha (Sumitomo Corporation), Toyota Jidosha Kogyo Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ishikawa, Masakazu, Hirai, Akiyoshi, Ito, Sadayoshi, Noguchi, Takeshi
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Nowicki, Joseph E.
• Application Number:
  US05/500,681
• Time in Patent Office: 778 Days
• Field of Search: 340/52 A, 200/61.4, 200/61.44, 188/1 A
• US Class Current: 340/454
• CPC Class Codes: F16D 55/228 with a separate actuating member for each side
• CPC Class Codes: F16D 65/0975 Springs made from wire
• CPC Class Codes: F16D 66/024 Sensors mounted on braking members adapted to contact the brake disc or drum, e.g. wire loops severed on contact

Abstract

A warning mechanism for detecting brake shoe wear is adapted to be fitted into a recess formed on the rear face of a brake shoe such that when the front face of the shoe, which undergoes frictional engagement during braking, is worn to a sufficient extent, a defaceable detection wire in the warning mechanism will be ruptured to provide an indication of depletion of the braking material of the shoe. The detector element is removably secured within the recess of the brake shoe and is located such that it will not be dislodged by a braking force applied to the brake shoe by a piston of the brake assembly but will, instead, be held in position thereby.

Claims

1. A warning mechanism for detecting brake shoe wear in a wheel braking assembly including a brake shoe having a first side and a second side, a rotatable disc fixed relative to said wheel and positioned to be frictionally engaged by said first side of said brake shoe, piston means disposed to apply a braking force against said second side of said brake shoe and shim means interposed between said piston means and said second side of said brake shoe, said warning mechanism comprising means defining a recess in said second side of said brake shoe at a part of said second side normally contacted by said piston, said recess extending from said second side partially through said brake shoe and terminating a distance from said first side, a defaceable detection element removable fitted in said recess and held in place by said piston means, said shim means extending over said detection element between said piston means and said detection element with the braking force applied by said piston means being directed to bear against said detection element in the direction toward said disc to hold said removably fitted detection element in place within said recess to prevent displacement thereof during operation of said braking assembly, said detection element being removable from said recess by withdrawal therefrom out of said recess from said second side of said brake shoe when replacement of said brake shoe or of said detection element is desired, said detection element including a portion thereof extending from said second side of said brake shoe toward said disc in a direction generally transversely to the direction of rotation of said disc, and a warning signal generating device connected with said detection element and adapted to produce a warning signal indicating brake shoe wear when the first side of said brake shoe has been worn down by an amount sufficient to cause breakage of said detection element by contact of said detection element with said rotatable disc.

2. A mechanism according to claim 1 wherein said warning signal generating device and said detection element are comprised of an electrical circuit operable to generate a signal indicating brake shoe wear upon breakage of said detection element.

3. A mechanism according to claim 2 wherein said detection element includes a defaceable conductor wire connected as part of said electrical circuit.

4. A mechanism according to claim 3 wherein said detection element includes a body portion composed of defaceable electrically insulating resinous plastic material having said conductor wire embedded therein.

5. A mechanism according to claim 4 wherein said detection element body portion is formed in a generally L-shaped configuration having one leg thereof extending from said second side of said brake shoe toward said first side thereof.

6. A mechanism according to claim 4 wherein said recess defined in said brake shoe is formed with a configuration generally coinciding with the configuration of said detection element body portion to prevent displacement of said detection element relative to said brake shoe in directions extending transversely of the direction of the braking force applied by said piston means.

7. A mechanism according to claim 1 wherein said brake shoe comprises brake friction material located on said first side thereof and adapted to be pressed against said rotatable disc in the development of a braking force, and a retaining member located on said second side thereof for retaining said brake friction material in place, and wherein said brake shoe recess is defined by a hole extending through said retaining member and a recess formed in said friction material at a position aligned with said hole.