Brake Overstroke Indicator Cam Mechanism
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Solution Overview
Problem
Existing brake overstroke indication systems for heavy-duty vehicles are unreliable due to mechanical complexity and fragility, and electronic systems are prone to damage from hostile environments, especially with automatic slack adjustment systems.
Innovation Solution
A reliable brake overstroke indication system that includes an indicator adjustment shaft with a biasing member, an overstroke sensor, and a cam mechanism that provides visual and electrical signals for overstroke detection, protected from environmental hazards by housing the sensors within the brake assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a brightly colored ring is painted on the push rod to indicate overstroke, then visual indication is provided, but the indication becomes difficult to see due to location and accumulated road debris
Solution Approach 1:
The indication function is extracted from the push rod itself and transferred to a separate indicator mechanism that rotates independently. This allows the indication to be positioned optimally for visibility while remaining functionally coupled to the push rod through the sensor system.
Solution Approach 2:
An overstroke sensor acts as an intermediary between the push rod position and the visual indicator. The sensor detects push rod position and triggers the indicator mechanism, providing reliable electrical detection while keeping the visual indication separate from the mechanical push rod.
2Measurement precision
If electronic monitoring systems with sensors are used, then overstroke detection capability is improved, but the linkages become complicated and fragile
Solution Approach 1:
The overstroke sensor serves multiple functions: it detects push rod position, triggers the visual indicator, and can provide electrical signals for additional monitoring systems. This multi-functionality reduces the need for separate detection mechanisms and simplifies the overall system.
Solution Approach 2:
The indicator mechanism is self-activating through the sensor detection system. When the sensor detects overstroke conditions, it automatically triggers the visual indicator without requiring additional linkages or manual intervention, reducing mechanical complexity.
3Measurement precision
If electronic sensors are exposed in the hostile brake environment, then overstroke monitoring is enabled, but the sensors are prone to damage from environmental factors
Solution Approach 1:
The overstroke sensor is nested within the brake actuator housing, placing it in a protected environment while maintaining its ability to detect push rod position through the housing structure. This shielding protects the sensor from direct exposure to harsh environmental conditions.
Solution Approach 2:
The housing structure acts as a protective shell around the sensor, isolating it from environmental hazards such as moisture, debris, and extreme temperatures while allowing the sensor to function through controlled openings or transparent sections.
4Productivity
If automatic slack adjusters are used to compensate for slack, then braking system performance is improved, but the push rod stroke requirement decreases making overstroke detection more complex
Solution Approach 1:
The overstroke sensor provides continuous feedback on push rod position, allowing the system to detect when the push rod extends beyond the normal range even as the slack adjuster modifies the required stroke. This feedback mechanism adapts to the changing stroke requirements while maintaining detection capability.
Solution Approach 2:
The sensor detection threshold is configured to account for the reduced stroke requirements caused by automatic slack adjustment. By adjusting the detection parameters rather than the mechanical system, the indication system remains simple while adapting to the modified operating conditions.
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 system effectively indicates overstroke conditions to operators and mechanics, ensuring reliable operation and maintenance while withstanding harsh environments, and is cost-effective and easily integrated with automatic slack adjustment systems.
Implementation Method 1
an indicator adjustment shaft biased toward a housing portion such that an indicator post extends through an aperture in the housing portion
Implementation Method 2
an operating shaft assembly which rotates about a pivot axis when the push rod extends past an overstroke condition... The cam member drives the cam surface member and the indicator adjustment shaft to overcome a biasing member
Data Source
AI summary
A vehicle brake assembly provides an indicator system in which the operating shaft assembly rotates about a pivot axis to rotate a cam member attached thereto against a cam surface which extends from an indicator adjustment shaft. The cam member drives the cam surface and attached indicator adjustment shaft to overcome a biasing member, actuate an overstroke sensor, and simultaneously retract an indicator post to provide a visual indication. Another indicator system includes an overstroke sensor located within the brake housing in an angular position relative the pivot axis adjacent a path of the operating shaft assembly. Another indicator system includes a mechanical overstroke member that buckles in response to contact with the operating shaft to provide overstroke identification from outside the brake housing.