Two-Speed Trailer Jack with Nested Sleeves and Variable Thread Pitch
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Solution Overview
Problem
Conventional linear trailer jacks require numerous rotations of a handle to lift heavy loads due to constant thread pitch, making the process time-consuming and inefficient.
Innovation Solution
A two-speed linear jack system featuring a high-speed assembly with a larger thread pitch for rapid extension and a low-speed assembly with a smaller thread pitch for mechanical advantage when lifting heavy loads, automatically switching between modes based on ground contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant thread pitch is used in conventional linear trailer jacks, then the structure is simple, but numerous handle rotations are required to lift heavy loads, making the process time-consuming
Solution Approach 1:
The patent applies dynamics by making the thread pitch variable rather than constant. The jack mechanism transitions between different thread pitches (first thread pitch for rapid extension, second thread pitch for lifting heavy loads) based on operational requirements. This dynamic change in mechanical parameters allows the system to optimize both speed and mechanical advantage at different stages of operation, resolving the contradiction between lifting speed and structural simplicity.
Solution Approach 2:
The patent implements parameter changes by varying the thread pitch parameter throughout the operation cycle. The screw mechanism uses a first thread pitch during initial extension for rapid movement, then transitions to a second thread pitch for the lifting phase to provide greater mechanical advantage. This parameter variation enables the system to achieve both fast extension and efficient heavy load lifting without requiring a complex multi-component structure.
2Productivity
If a larger thread pitch is used for rapid extension, then the number of handle rotations is reduced, but mechanical advantage is decreased making it difficult to lift heavy loads
Solution Approach 1:
The patent applies periodic action by using different thread pitches at different periods of the operation cycle. During the initial extension period, a larger first thread pitch is used for rapid movement. During the subsequent lifting period, a smaller second thread pitch is engaged to provide the necessary mechanical advantage for heavy loads. This periodic switching between thread pitch configurations allows the system to optimize for speed when needed and for force when needed, eliminating the need to choose one parameter over the other.
3Force
If a smaller thread pitch is used for mechanical advantage, then heavy loads can be lifted, but the number of handle rotations increases significantly
Solution Approach 1:
The patent applies segmentation by dividing the lifting operation into two distinct phases, each utilizing a different thread pitch optimized for that specific phase. The first phase uses a larger thread pitch for rapid extension over a short distance, and the second phase uses a smaller thread pitch for the actual lifting operation. This segmentation allows the system to minimize total handle rotations by using the appropriate thread pitch for each segment of the operation, thereby reducing overall time loss while maintaining the ability to lift heavy loads.
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 handle rotations needed to lift loads, 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 sleeve is threadedly coupled to the second sleeve, a shaft, a third sleeve configured to receive the shaft, the third sleeve disposed at least partially within the first sleeve, a translating screw disposed at least partially within the third sleeve, wherein the third sleeve is threadedly coupled to the translating screw
Implementation Method 2
a translating screw disposed at least partially within the third sleeve, wherein the third sleeve is threadedly coupled to the translating screw
Data Source
AI summary
A linear jack includes a first sleeve disposed at least partially within a second sleeve (the first sleeve and the second sleeve collectively a high speed assembly), a third sleeve disposed at least partially within the first sleeve, and a translating screw disposed at least partially within the third sleeve (the third sleeve and the translating screw collectively a low speed assembly). The linear jack further includes a fourth sleeve fixed to the second sleeve and configured to translate therewith. The fourth sleeve extends over the third sleeve and transfers axial loads between the second sleeve and the third sleeve to extend the high speed assembly together with the low speed assembly from an outer case of the linear jack.