Railcar Container Lock Dynamic Pivot Axis Mechanism
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Solution Overview
Problem
Existing latch type container locks for railcars face challenges in maintaining consistent engagement and disengagement forces due to varying spring rates and friction, requiring separate springs for insertion and extraction, which complicates design and reliability.
Innovation Solution
A container lock design featuring a post with a pivotable latch arm and a compression spring that changes pivot axis during insertion and extraction, providing a larger mechanical advantage during extraction, allowing for a consistent spring travel distance and reduced friction impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single latch arm with a single pivot axis is used, then the device complexity is reduced, but the reliability of maintaining consistent engagement and disengagement forces deteriorates
Solution Approach 1:
The latch arm dynamically changes its pivot axis between two positions: a first pivot axis during insertion that provides mechanical advantage for engagement, and a second pivot axis during extraction that provides mechanical advantage for disengagement. This dynamic adaptation allows a single latch arm to reliably achieve both the 800 lbs maximum engagement force and the 1600-2200 lbs extraction force range required by AAR Specification M-952.
2Reliability
If separate springs are used for insertion and extraction, then the reliability of force control is improved, but the device complexity increases
Solution Approach 1:
A single compression spring is positioned to bias the latch arm for both insertion and extraction operations. The spring works in conjunction with the changing pivot axis to provide appropriate mechanical advantage at each stage, eliminating the need for separate springs and reducing overall system complexity while maintaining reliable force control throughout the latch cycle.
3Force
If friction is reduced in the latch mechanism, then the extraction force requirement becomes easier to meet, but the engagement force control becomes less predictable
Solution Approach 1:
The invention accepts that friction will be present in the latch mechanism but compensates for it through the changing pivot axis mechanism. The second pivot axis during extraction is specifically positioned to provide additional mechanical advantage that accounts for friction losses, ensuring that the net extraction force still falls within the 1600-2200 lbs range while maintaining predictable engagement force control through the first pivot axis.
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 design enhances reliability and predictability by maintaining consistent latch travel and reducing friction dependence, enabling easier spring design and more reliable latching and unlatching operations.
Implementation Method 1
A compression spring is positioned to bias the at least one latch arm
Implementation Method 2
Changing from the first pivot axis to the second alters a mechanical linkage in such a way that force developed in the spring acts through a substantially larger lever arm during extraction than it does during insertion
Data Source
AI summary
In a container lock for insertion into a locking aperture, a post is provided insertable into and extractable from the locking aperture. At least one latch arm is provided within the post and which projects laterally from a side of the post. The latch arm is pivotable about a first pivot axis during insertion and about a second pivot axis spaced from the first pivot axis during at least a beginning of extraction. A compression spring is positioned to bias the at least one latch arm.