Movable Step Assembly for Autorack Door Vibration Reduction
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Solution Overview
Problem
The existing autorack car doors, particularly the folding type, are prone to longitudinal vibration at their lowest natural frequency, which can lead to vibration-induced fatigue and maintenance challenges due to their design and construction, including the collection of debris that can cause rusting and require frequent cleaning.
Innovation Solution
A movable step assembly for autorack cars that includes a foot rung with a cross-member and side members, featuring an indexing mechanism that allows the step to be deployed or stowed without the need for springs or removable pins, ensuring it remains attached to the door and can be easily transitioned between positions using gravity, thereby reducing vibration and maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If access fittings are made movable to adapt to different operating conditions, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The access fitting is designed as a movable assembly that can transition between deployed and stowed positions. The fitting includes a movable portion with foot rungs that can be positioned outwardly for access or inwardly against the door panel, allowing adaptation to different operational conditions without complex locking mechanisms.
Solution Approach 2:
The movable access fitting utilizes gravity as its biasing mechanism rather than springs or removable pins. The fitting automatically returns to its stowed position when released, eliminating the need for additional locking parts and simplifying the overall device complexity while maintaining operational flexibility.
2Reliability
If additional locking mechanisms like springs or removable pins are added to secure the step, then reliability is improved, but device complexity and ease of operation worsen
Solution Approach 1:
The system uses gravity as a natural biasing force rather than mechanical springs. The access fitting's weight provides the restoring force that returns it to the stowed position, eliminating the need for additional spring components while maintaining reliable positioning.
Solution Approach 2:
The design removes removable pins and complex locking mechanisms from the system. The indexing members engage with slots and detents to provide reliable positioning without requiring user-operated locking components, simplifying both the device structure and operation.
3Ease of operation
If the step assembly uses gravity biasing without springs or pins, then ease of operation is improved, but reliability may worsen
Solution Approach 1:
Indexing members act as intermediaries between the movable access fitting and the door panel. These indexing members engage with slots and detent features to provide positive positioning and secure engagement, ensuring reliable operation while maintaining ease of use through gravity-based movement.
Solution Approach 2:
The indexing mechanism includes detent features and slot engagements that prepare and secure the access fitting in its deployed position before use. This beforehand securing ensures reliable positioning while allowing easy deployment and retraction through gravity assistance.
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 step assembly effectively reduces door vibration and simplifies maintenance by allowing the step to be easily moved between deployed and stowed positions without additional parts, using gravity for locking, thus minimizing the effort required for operation and reducing the risk of rusting and debris accumulation.
Implementation Method 1
utilizing a key-like mechanism for positioning that is biased by gravity for energy efficiency
Data Source
AI summary
An autorack railroad car has a housing surmounting an underframe. The underframe defines a first or main deck. The housing, or “rack” defines at least one additional deck spaced upwardly from the main deck. The housing has end doors. The end doors may be folding end doors, such as a tri-fold hinged door. When closed, the door may be secured by latches at top and bottom. The car may have a movable sill-step, or foot-hold that is movable between a deployed or extended position, and a stowed or retracted position. The movable step may be mounted to a panel of the door. The movable step may be biased away from any position between the stowed and retracted positions. The movable step may be free of springs that may break, and free of pins or other items requiring careful removal and replacement. The movable parts of the step assembly may be captured by the stationary parts to prevent them from coming loose or falling off.