Two-Speed Trailer Jack with Variable Thread Pitch
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Solution Overview
Problem
Conventional linear trailer jacks require numerous rotations to lift heavy loads due to a constant small thread pitch, making the process time-consuming and inefficient.
Innovation Solution
A two-speed linear jack system with a high-speed assembly and a low-speed assembly, where the high-speed assembly has a greater thread pitch than the low-speed assembly, allowing for more linear extension per rotation, and automatically switches to low-speed mode upon ground contact to provide mechanical advantage for lifting heavy loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a constant small thread pitch is used in conventional linear trailer jacks, then mechanical advantage is maintained for lifting heavy loads, but the number of rotations required to lift the jack increases, making the process time-consuming
Solution Approach 1:
The patent applies dynamics by making the thread pitch variable rather than constant. The jack automatically transitions between a first thread pitch (coarser) for rapid extension and a second thread pitch (finer) for lifting, allowing the system to adapt its mechanical properties based on operational phase. This dynamic adjustment resolves the contradiction by providing both speed and mechanical advantage at appropriate times.
Solution Approach 2:
The patent changes the thread pitch parameter during operation. The first outer sleeve engages with the inner sleeve at a first thread pitch during rapid extension, then engages at a second thread pitch with greater mechanical advantage for lifting. This parameter change allows the system to overcome the time-loss contradiction by optimizing the thread pitch for each operational stage.
2Productivity
If a coarser thread pitch is used to reduce the number of rotations, then lifting speed increases, but mechanical advantage decreases, making it difficult to lift heavy loads
Solution Approach 1:
The system dynamically switches between two thread pitch configurations. During the rapid extension phase, the coarser first thread pitch provides high productivity. During the lifting phase, the finer second thread pitch provides high mechanical advantage. This dynamic switching resolves the contradiction between lifting speed and mechanical advantage.
Solution Approach 2:
The lifting operation is segmented into two distinct phases: rapid extension using the first thread pitch, and controlled lifting using the second thread pitch. This segmentation allows each phase to use the optimal thread pitch for its specific function, resolving the contradiction between speed and force.
3Productivity
If a two-speed system with variable thread pitch is implemented, then both lifting speed and mechanical advantage are optimized, but device complexity increases
Solution Approach 1:
The patent uses a nested structure where the first outer sleeve and second outer sleeve are concentric, and the inner sleeve is nested within both. This nesting allows the complex two-speed mechanism to be compact and integrated, reducing the impact of added complexity on overall device size and structure.
Solution Approach 2:
The inner sleeve serves multiple functions: it engages with the first outer sleeve during rapid extension and engages with the second outer sleeve during lifting. This multi-functionality reduces the need for separate mechanisms, thereby limiting the increase in device complexity while achieving two-speed operation.
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 two-speed system reduces the number of rotations needed to lift or lower the jack, improving efficiency and ease of use by quickly extending to reach the ground surface while maintaining mechanical advantage for heavy loads.
Implementation Method 1
the first outer sleeve is threadedly coupled to the inner sleeve, the second outer sleeve is threadedly coupled to the translating screw
Implementation Method 2
the second outer sleeve is threadedly coupled to the translating screw
Implementation Method 3
a spring operatively coupled to the high speed outer shaft, wherein the first outer sleeve is slidable in the outer tube between a first position and a second position. In the first position, the spring biases the first outer sleeve to engage the gear
Data Source
AI summary
A linear jack includes an outer tube, a high speed assembly comprising a first rotating member threadedly coupled to a first translating member, a low speed assembly comprising a second rotating member threadedly coupled to a second translating member, wherein the low speed assembly is coupled to and translates with the first translating member. At least a portion of the high speed assembly is slidable in the outer tube between a first position, wherein the high speed assembly is engaged with a shaft, and a second position, wherein the high speed assembly is disengaged from the shaft. A thread pitch of the high speed assembly is greater than a thread pitch of the low speed assembly.