Strap Winch Assembly With Pivotable Pawl And Braking Member
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Solution Overview
Problem
Existing strap tie down winches require multiple insertions and removals of a winding bar to tension the strap and lack controlled tensioning and loosening mechanisms, leading to uncontrollable unwinding when the brake is disengaged.
Innovation Solution
A winch apparatus with a pivotable handle and pawl that engages with the drum gear to tension the strap and a braking member to control tension, allowing for controlled tensioning and partial loosening by intermittent contact with the drum gear and braking member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a winding bar is used to wind the drum through circumferential apertures, then the drum can be tensioned, but the necessity of inserting and removing the bar multiple times increases operation complexity and time consumption
Solution Approach 1:
The patent applies the dynamics principle by making the pawl pivotable relative to the handle. This allows the pawl to dynamically engage and disengage from the drum gear teeth during rotation, enabling continuous tensioning without repeated insertion and removal of the entire handle assembly. The pivotable connection transforms a static, discrete operation into a dynamic, continuous process.
Solution Approach 2:
The patent uses the pawl as an intermediary element between the handle and the drum gear. The pawl translates the rotational motion of the handle into controlled engagement with the gear teeth, mediating the force transmission and enabling continuous winding without direct insertion into aperture holes.
2Ease of operation
If the drum brake is disengaged by force to loosen the strap, then the drum can rotate to loosen the strap, but the drum will unwind uncontrollably and the strap will lose all tension
Solution Approach 1:
The patent applies dynamics by making the braking member pivotable rather than fixed. This allows the brake to dynamically transition between engaged and disengaged states based on the pawl's position during handle rotation. The brake can be temporarily disengaged for controlled loosening while automatically re-engaging to maintain tension, providing reliable controlled loosening without uncontrollable unwinding.
Solution Approach 2:
The patent implements self-service through the spring-biased braking member that automatically returns to the engaged position after temporary disengagement. The spring bias causes the brake to self-reengage after the pawl moves past it during handle rotation, eliminating the need for manual re-engagement and ensuring automatic tension maintenance.
3Reliability
If a spring biased pawl is used to prevent loosening rotation, then the strap tension is maintained, but the device complexity increases with additional components
Solution Approach 1:
The patent merges the braking function with the handle assembly by integrating the spring-biased pawl directly into the handle structure. This combination eliminates the need for a separate braking mechanism and reduces overall device complexity while maintaining reliable strap tension through the integrated brake that engages with the drum gear.
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
Eliminates the need for multiple winding bar insertions and provides controlled tensioning and loosening of the strap, preventing uncontrollable unwinding and maintaining strap tension.
Implementation Method 1
a spring biased pawl that permits strap (tensioning) rotation of the winding drum but prevents loosening rotation
Implementation Method 2
a braking member to arrest inadvertent rotation of the drum gear in order to maintain strap tension
Data Source
AI summary
A strap winch apparatus includes a frame with a drum gear connected to a drum. The drum is configured to receive an end of a strap whereby the strap is wound around or unwound from the drum when the gear is rotated. The frame also includes a braking member to arrest inadvertent reverse rotation of the drum to maintain strap tension. A handle configured to engage with the drum includes a pivotable pawl. One end of the pawl is configured to engage the gear teeth of the drum gear and index the drum gear in order to tension the strap about the drum. An opposite end of the pawl is configured to displace the braking member whereby the gear and drum are permitted to rotate in a direction loosening the strap tension. Typically, the braking member has a gear tooth engaging portion and a striking portion that may be in intermittent contact with the pawl for controlled loosening of the strap tension.