Locking Pliers Overcenter Linkage Anti-Backlash Mechanism
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Solution Overview
Problem
Locking pliers in an overcenter position are prone to unintentionally springing open when bumped or disturbed, leading to disengagement from the work piece due to the lack of effective retention mechanisms.
Innovation Solution
The design incorporates an overcenter linkage with a lock member that can be moved between locking and release configurations, utilizing a spring to bias the jaws closed and a linkage latch or pivot latch to prevent unintended movement, ensuring the jaws remain locked even when bumped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locking pliers use an overcenter linkage mechanism, then the pliers can maintain a locked position compressing jaws against a work piece, but the pliers may unintentionally spring open and disengage when bumped or disturbed
Solution Approach 1:
The lock member is positioned and configured to preemptively counteract forces that would cause unintended opening. When the pliers are in the overcenter locked position, the lock member engages with the release lever to create a mechanical barrier that prevents the linkage from moving back toward the open position, even when subjected to bumps or disturbances.
Solution Approach 2:
The lock member is automatically engaged when the pliers reach the overcenter locked position, performing the locking action in advance before any unintended opening force is applied. This automatic engagement ensures the pliers are secured against accidental opening without requiring additional user action.
2Reliability
If a lock member is added to prevent unintentional opening, then the pliers maintain secure locking, but the device complexity increases
Solution Approach 1:
The lock member and release lever are integrated into the existing overcenter linkage mechanism, sharing common components and movement paths. The lock member utilizes the same pivot points and linkage geometry as the primary locking mechanism, combining multiple functions into a unified system rather than adding separate independent mechanisms.
Solution Approach 2:
The lock member serves multiple functions: it acts as both a locking element that prevents unintended opening and a mechanical indicator that shows the pliers are securely locked. The release lever simultaneously controls both the unlocking action and the disengagement of the lock member, consolidating control functions into a single user interface element.
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 effectively prevents unintentional unlocking of the pliers, maintaining a secure grip on the work piece even when subjected to bumps or disturbances, thereby enhancing the reliability of the locking mechanism.
Implementation Method 1
an overcenter linkage operatively connected between the upper structure and the lower structure, the linkage biasing the lower handle and the lower jaw away from the upper handle and the upper jaw, respectively, when in a jaw-opening position
Data Source
AI summary
Pliers include upper structure including an upper jaw and handle extending therefrom, and lower structure including a lower jaw and handle. The lower jaw may pivot relative to the upper jaw, and the lower handle may pivot relative to the lower jaw. An overcenter linkage operatively connects between the upper and lower structure, biasing the lower handle and jaw away from the upper handle and jaw, respectively, when in a jaw-opening position, and enabling the lower jaw and handle to be retained in a closed configuration when the linkage is in a jaw-closing position. A lock member is movable between a locking configuration preventing pivoting of the lower handle from the closed configuration and retaining the jaws in a closed position, and a release configuration enabling the lower handle to be moved away from the closed configuration, allowing the jaws to move to an open position.