Drum Brake Automatic Play Adjustment Device
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Solution Overview
Problem
Existing automatic play adjustment devices for drum brakes are complex to install, require multiple modifications for different sizes, and rely on springs for connection, making them inefficient for rapid compensation of wear-induced play in friction pads.
Innovation Solution
A simplified automatic play adjustment device for drum brakes that uses a screw and nut screw mechanism with a ratchet gear and bell crank, eliminating the need for springs and allowing easy adaptation to various brake sizes through modular design, featuring a bimetallic element for temperature compensation and a single-piece metallic body for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-based connection mechanism is used to connect the adjustment device to the brake shoes, then the device can maintain constant contact force, but the installation becomes complex and requires multiple modifications for different brake sizes
Solution Approach 1:
The patent removes the spring-based connection mechanism from the adjustment device, eliminating the complex installation requirements and modifications needed for different brake sizes. The adjustment device is now directly mounted to the brake drum without requiring spring connections to the brake shoes, thereby simplifying installation while maintaining adjustment reliability through the screw and nut mechanism.
2Reliability
If a complex spring-based adjustment mechanism is used, then the device can compensate for wear, but the response time is delayed and manufacturing costs increase
Solution Approach 1:
The patent replaces the complex spring-based mechanical adjustment mechanism with a simpler screw and nut screw mechanism. This substitution eliminates the delay inherent in spring-based systems and provides more rapid response to wear-induced play. The screw mechanism allows for direct, precise adjustment without the intermediate compliance of spring elements, thereby reducing response time while maintaining wear compensation capability.
3Reliability
If multiple components and springs are used in the adjustment device, then the connection can be maintained, but manufacturing costs increase and durability decreases
Solution Approach 1:
The patent merges multiple separate components into a more integrated assembly. The adjustment device is mounted directly to the brake drum as a unified structure, eliminating the need for separate spring components and their associated mounting hardware. This merging reduces the total number of parts, simplifies manufacturing, and improves durability by reducing the number of potential failure points while maintaining connection stability through the direct mounting structure.
4Reliability
If the adjustment device is designed for specific brake sizes, then the connection can be optimized, but the adaptability to different brake sizes is reduced
Solution Approach 1:
The patent designs the adjustment device with universal mounting capabilities that allow it to be installed on brake drums of various sizes. The direct mounting structure to the brake drum, rather than size-specific spring connections, enables the same adjustment mechanism to be applied across different brake configurations. This universal design maintains connection reliability through proper mounting while significantly improving adaptability to different brake sizes.
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
The solution enables easy installation, reduced manufacturing costs, broader applicability, rapid response to wear-induced play, and improved durability by eliminating spring reliance and optimizing component alignment, while preventing false adjustments due to heat expansion.
Implementation Method 1
a bimetallic element for temperature compensation
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The adjustment device (32) comprises a body (34) intended to cooperate with a first shoe (14) of the drum brake (10) and an adjustment mechanism (44, 46, 60, 62, 72) intended to cooperate with a second shoe (16) of the drum brake (10) in order to adjust the distance, in the rest condition, between said shoes (14, 16) depending on the wear level of friction pads (18, 20) provided on the shoes (14, 16). The body (34) has, at its end facing the adjustment mechanism (44, 46, 60, 62, 72), a hole (42). The adjustment mechanism (44, 46, 60, 62, 64, 72) comprises a nut screw (44) and a screw (46), the nut screw (44) being pushed against the second shoe (16) and the screw (46) including a first shank portion (56) received in the hole (42) of the body (34) so as to be free to slide along the axis (x) of this hole (42) relative to the body (34), and a second threaded shank portion (58) on which the nut screw (44) is screwed. The adjustment mechanism (44, 46, 60, 62, 64, 72) further comprises a ratchet gear (60, 62) which includes a gearwheel (60) rigidly connected to the screw (46) and a ratchet (62) designed to cooperate with the teeth of the gearwheel (60), an elastically deformable connection element (64) which connects the ratchet (62) to the body (34) and is configured so as to keep, in the rest condition, the ratchet (62) engaged with the gearwheel (60) and cause, following deformation thereof, disengagement of the ratchet (62) from the gearwheel (60), and deformation means (72) designed to deform the connection element (64) depending on the amount of the relative translational movement of the body (34) with respect to the nut screw (44) resulting from the relative movement of the two shoes (14, 16).