Tripod Linkage Mechanism for Rapid Manhole Size Adjustment
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Solution Overview
Problem
Conventional tripod devices for raising and lowering workers into manholes are limited by their fixed design, requiring adjustment of webbing or chains to accommodate different manhole sizes, which is inefficient and not adaptable to varying opening angles or sizes.
Innovation Solution
A fast-adjusting tripod system with a central frame, pivot-mounted legs, a linkage mechanism, and a stop mechanism that locks the legs at multiple predetermined angles, allowing for quick adjustment to various manhole diameters and sizes by engaging stop surfaces on the linkage mechanism and frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the tripod is designed for one maximum manhole size with fixed legs, then the structure is simple and stable, but it cannot adapt to different manhole sizes or opening angles
Solution Approach 1:
The tripod legs are made dynamically adjustable through a linkage mechanism with stops that allow the legs to pivot between multiple fixed angular positions. This enables the tripod to adapt to different manhole sizes while maintaining structural stability at each position, resolving the contradiction between adaptability and structural simplicity.
Solution Approach 2:
The adjustment mechanism is segmented into discrete stop positions along the linkage mechanism. Each stop provides a predetermined pivot angle position, allowing the legs to be quickly adjusted to specific angles corresponding to different manhole sizes without requiring continuous adjustment, thus maintaining relative structural simplicity while achieving adaptability.
2Adaptability or versatility
If webbing or chain is adjusted to accommodate different manhole sizes, then adaptability is improved, but the adjustment process becomes time-consuming and inefficient
Solution Approach 1:
The linkage mechanism with multiple stops provides rapid adjustment capability by allowing the legs to pivot between predetermined angular positions. This eliminates the need for time-consuming webbing or chain adjustments, as the mechanical linkage can be quickly repositioned to the appropriate stop corresponding to the required manhole size.
Solution Approach 2:
The stop positions are pre-configured at specific pivot angles during manufacturing to correspond to common manhole sizes. This preliminary setup eliminates the need for field calculations or complex adjustments, allowing operators to quickly select the appropriate stop position based on the manhole dimensions without time-consuming adjustments to webbing or chains.
3Adaptability or versatility
If the tripod legs are made adjustable to various angles, then versatility is improved, but the stability and reliability of the anchor may be compromised
Solution Approach 1:
The linkage mechanism provides controlled dynamic adjustment with predetermined stop positions that ensure the legs are locked at specific, engineered angular positions. Each stop position is designed to maintain adequate stability and reliability for the intended application, preventing arbitrary positioning while still allowing adaptation to different manhole sizes.
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4b
AI summary
A fast adjusting tripod system (10) is provided for supporting the weight of a worker during entry to and exit from a manhole beneath the tripod system (10). The tripod system (10) includes a central frame (16); three support legs (18) extending from the frame (16), with each of the legs (18) being pivot mounted to the frame (16); a linkage mechanism (20) operably connecting the legs (18) to pivot together relative to the frame (16); and a stop (22) configured to selectively lock the linkage mechanism (20) against movement relative to the frame (16) at a plurality of distinct, predetermined pivot angle positions of the legs (18) relative to the frame (16).