Angled Hold-Down Spring Resolves Brake Shoe Clearance
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Solution Overview
Problem
Existing spot-type disc brakes experience residual brake torque and thermal loading due to friction, as well as poor clearance behavior and corrosion issues, particularly because the brake shoes remain in contact with the disc after braking and lack effective thermal uncoupling.
Innovation Solution
The abutment surface of the hold-down spring is arranged anti-parallel to the axis of movement, producing both radial and axial force components, which enhance the clearance behavior by creating a small air gap between the brake shoe and disc, and using an angled design (α > 0°) to facilitate the return of the piston and brake shoe to their initial position, while minimizing corrosion through a small contact area or multi-part design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake shoe remains in contact with the brake disc after braking, then the brake provides continuous friction force, but the residual brake torque increases and thermal loading worsens
Solution Approach 1:
The hold-down spring is pre-configured with an angled abutment surface that generates a retracting force component parallel to the piston movement axis. This preliminary anti-action counteracts the tendency of the brake shoe to remain in contact with the disc, automatically pushing it away to eliminate residual torque before it can build up significantly.
Solution Approach 2:
The angled abutment surface is designed to activate the retracting force as soon as the brake is released, performing the clearance action in advance before the brake shoe can settle into a persistent contact state. This preliminary action ensures the air gap is re-established quickly, preventing residual torque accumulation.
2Reliability
If the brake shoe remains in contact with the brake disc after braking, then friction force is maintained, but thermal uncoupling between pad and disc deteriorates
Solution Approach 1:
The hold-down spring with angled abutment surface creates a preliminary retracting force that prevents the brake shoe from remaining in thermal contact with the disc. This anti-action interrupts the heat transfer path from disc to pad, allowing thermal uncoupling to occur automatically when the brake is released.
3Ease of operation
If the abutment surface is arranged anti-parallel to the axis of movement, then clearance behavior improves, but the device complexity increases
Solution Approach 1:
The hold-down spring with angled abutment surface performs multiple functions simultaneously: it provides radial preloading to prevent rattling, generates axial retracting force for clearance, and maintains structural simplicity. This multi-functionality resolves the contradiction by achieving improved clearance behavior without significantly increasing device complexity.
4Object-affected harmful factors
If the contact area between hold-down spring and abutment surface is reduced, then corrosion decreases, but the reliability of the connection may worsen
Solution Approach 1:
The abutment surface is designed with a specific angle and localized contact area that optimizes the distribution of spring force. This local quality optimization ensures sufficient connection stability through proper force distribution while minimizing the contact area exposed to corrosive environments, thereby reducing corrosion risk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces residual brake torque, improves clearance behavior, and minimizes thermal loading by ensuring effective uncoupling of the brake shoes from the disc, while also reducing corrosion and maintaining cost-effectiveness through integral or multi-part design and the use of wire or leaf springs.
Implementation Method 1
a hold-down spring is provided on the side of the actuating unit between an abutment surface in the housing bridge and the brake shoe, the said spring preloading the brake shoe in relation to the mounting support
Implementation Method 2
the abutment surface of the hold-down spring in the housing bridge is arranged anti-parallel to the axis of movement... not only a radial preloading force is produced... but also a force component normal thereto
Implementation Method 3
they still bear against the brake disc and, induced by friction, produce a residual brake torque, the so-called residual moment
Data Source
AI summary
A spot-type disc brake with a housing comprising a housing bridge, with at least one housing leg having an actuating assembly comprising an actuator unit and a component movable along an axis of movement. At least one brake shoe is arranged at the component and is slidably supported on at least one support. The brake shoe is braced with the support against an abutment surface by means of a hold-down spring. The abutment surface of the hold-down spring is arranged non-parallel to the axis of movement. Thereby, not only a radial preloading force FR is produced, but also a force component Fx normal thereto, which assists the retracting movement of the brake shoe from the brake disc, thus improving the clearance behavior.