Telescopic Pushrod Sensor for Air Disc Brake Monitoring
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Solution Overview
Problem
Current brake monitoring systems for air disc brakes in heavy-duty vehicles are unable to effectively distinguish between over-stroke and hanging/dragging brake conditions due to the separation of the pushrod and lever arm, rendering existing systems non-functional for air disk brakes.
Innovation Solution
A vehicle brake monitor assembly with a telescoping pushrod and integrated sensor that detects movement between the pushrod and lever arm, allowing for the identification of normal, over-stroke, dragging, and out-of-adjustment conditions without modifying the conventional brake caliper, utilizing a sensor to detect differences in transmission along the contact member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pushrod monitoring system is used for air disc brakes, then the brake actuator status can be monitored, but the system cannot distinguish between over-stroke and hanging brake conditions due to pushrod-lever arm separation
Solution Approach 1:
The pushrod is segmented into a telescoping structure with an inner shaft and outer tube, allowing relative movement between segments. This segmentation enables the monitoring system to detect not only pushrod extension/retraction but also internal telescoping movements, providing distinct signals for over-stroke conditions versus hanging brake conditions where the lever arm separates from the pushrod tip.
Solution Approach 2:
A contact member with variable reflectivity is introduced as an intermediary between the pushrod and the sensor. This contact member translates the physical state of the pushrod-lever arm connection into optical signals that the sensor can detect. The variable reflectivity provides distinct optical signatures for different brake conditions, enabling reliable differentiation between over-stroke and hanging brake states.
2Ease of operation
If the lever arm is immobilized in an actuated position, then the brake remains applied, but the pushrod separates from the lever arm rendering monitoring systems non-functional
Solution Approach 1:
The monitoring system provides continuous feedback about the relationship between the pushrod and lever arm through the telescoping mechanism and variable reflectivity contact member. When the lever arm becomes immobilized and separates from the pushrod, the feedback signal changes distinctly, alerting the operator to the hanging brake condition rather than losing detection capability entirely.
Solution Approach 2:
The contact member utilizes variable reflectivity (an optical property change) to indicate different brake conditions. When the lever arm is properly connected to the pushrod, the contact member presents one reflectivity state; when separation occurs due to lever arm immobilization, the reflectivity state changes, providing visual/optical feedback about the brake status without requiring physical contact modification.
3Ease of manufacture
If existing monitoring systems are applied to air disc brakes, then installation is simple, but the systems cannot identify hanging brake conditions due to the non-fixed connection between pushrod and lever arm
Solution Approach 1:
The monitoring system is designed to be universal for air disc brake applications while performing multiple detection functions. The telescoping pushrod structure and variable reflectivity contact member enable the same system to detect normal operation, over-stroke conditions, and hanging brake conditions, providing multi-functional monitoring capability without requiring different systems for different detection needs.
Solution Approach 2:
The system embraces the dynamic nature of the pushrod-lever arm connection in air disc brakes rather than trying to rigidly fix it. The telescoping mechanism accommodates the natural movement and separation that occurs during operation, while the variable reflectivity contact member dynamically changes its optical properties based on the connection state, enabling accurate detection throughout the full range of operational conditions.
Data Source
AI summary
A vehicle brake monitor assembly for an air disk brake includes a brake actuator having a pushrod projecting from inside a chamber of said brake actuator. The pushrod releasably actuates a lever arm of a caliper thereby moving the disk brake into a braking position when the pushrod is in an extended position and releasing the disk brake from the braking position when the pushrod is in a retracted position. The pushrod includes a pushrod shaft and a contact member biased in a telescoping relationship relative to the pushrod shaft and the lever arm of the caliper abuts the contact member counteracting the bias of the contact member. A sensor is integrated with the assembly proximate the contact member and detects movement of the pushrod relative to the lever arm and to the pushrod shaft.