Strap Tensioning System Worm Gear Lock
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Solution Overview
Problem
Existing strap tensioning systems for securing cargo lack an efficient mechanism to vary the effective length of flexible straps and consistently produce tension, especially in compact spaces and under varying environmental conditions.
Innovation Solution
A strap tensioning system comprising a frame, core shaft, drive shaft, and gear assembly with a worm and worm gear, operated by a crank handle, which allows for the wrapping of straps around the core shaft to adjust effective length and produce tension, featuring a lock assembly for security and a compact design suitable for tight spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ratchet mechanism is used to tension the strap, then the strap can be progressively tensioned, but the mechanism lacks the ability to efficiently vary the effective length of the strap and produce consistent tension in compact spaces
Solution Approach 1:
The patent employs a nested arrangement where the worm gear is positioned within the frame structure, and the core shaft is nested within the gear assembly. The strap wraps around the core shaft which is centrally positioned, creating a compact nested configuration that maximizes space utilization while maintaining the tensioning function.
Solution Approach 2:
The patent transitions from a linear tensioning mechanism to a rotational mechanism by introducing the worm gear and core shaft arrangement. The strap is wrapped around the core shaft in a circular path, utilizing rotational motion to achieve tensioning instead of linear movement, thereby reducing the space required for the mechanism.
2Volume of moving object
If the tensioning mechanism is made compact for tight spaces, then it can be installed in limited areas, but the complexity of the mechanism increases
Solution Approach 1:
The worm gear mechanism provides self-locking capability due to the friction between the worm and worm gear teeth. This self-service feature automatically maintains the tensioned state without requiring additional locking components or complex control mechanisms, thereby reducing overall device complexity while maintaining compact size.
Solution Approach 2:
The core shaft acts as an intermediary element that translates the rotational motion from the worm gear into the wrapping motion of the strap. This intermediary component simplifies the overall mechanism by providing a clear mechanical linkage between the power source and the strap, reducing the need for additional complex transmission elements.
3Reliability
If manual operation with a crank handle is used, then the system is simple and reliable, but the productivity and speed of tensioning are limited
Solution Approach 1:
The patent employs a dynamic worm gear mechanism that can adapt to varying operational requirements. The manual crank handle provides reliable incremental tensioning through controlled rotational motion, while the worm gear's inherent friction characteristics allow for smooth, progressive tensioning that can be easily controlled by the operator, maintaining reliability while improving tensioning speed compared to ratchet mechanisms.
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 system effectively adjusts the effective length of flexible straps to produce consistent tension, enhancing cargo security and usability in tight spaces with a compact design and secure locking mechanism.
Implementation Method 1
a gear assembly made up of a worm and a worm gear that are driven by the drive shaft
Implementation Method 2
The crank handle has a body with a length projecting away from the second axis to a free end. The free end traces an annular path with a diameter as the crank handle is moved to operate the drive shaft
Data Source
AI summary
A strap tensioning system is provided. The system includes a frame comprising a first side wall that retains a ledge. A core shaft retains a flexible shaft and is rotatable by a drive shaft as urged by a crank handle. The crank handle supports an arm that is pivotable with respect to the crank handle, between a stowed position where the arm is substantially parallel to the crank handle, and a locking position where the arm is substantially perpendicular to the crank handle. The crank handle and arm are configured such that the arm disposed within the ledge when the crank handle is in registry with the ledge and the arm is in the locked position, thereby preventing rotation of the crank handle with respect to the frame.