Cross-Leg Footrest Height Adjustment With Fine Rack Locking
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Solution Overview
Problem
Existing height adjustable footrests often require manual operation and have support columns that project above the footrest, limiting freedom of movement and causing discomfort, while also struggling to maintain height under large loads with precise adjustments.
Innovation Solution
A footrest design with pivotable, mutually crossing leg structures and an adjustment mechanism featuring a rack and catch system that allows for small-step height adjustments without a projecting support column, using low, fine-toothed racks and a catch that engages transversely to resist shear forces, enabling easy one-foot operation and reliable load-bearing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rack and catch system is used with fine teeth for small-step adjustment, then height adjustment precision is improved, but the tooth load bearing resistance becomes insufficient under large loads
Solution Approach 1:
The catch engages the rack teeth in a direction transverse (perpendicular) to the direction in which the teeth project from the base. This dimensional change in engagement direction allows the teeth to be relatively low while still providing sufficient load bearing resistance, as the transverse engagement better resists shear forces. This resolves the contradiction by enabling fine teeth (for precision) to maintain adequate strength under load.
2Length of moving object
If support columns are extended to achieve maximum height, then height adjustment range is improved, but freedom of movement is limited and discomfort is caused
Solution Approach 1:
The footrest employs pivotable, mutually crossing leg structures that allow dynamic adjustment of height through angular changes, rather than requiring a statically extended support column. This dynamic mechanism achieves the required height adjustment range while keeping the support structure compact and non-obtrusive, thereby maintaining user freedom of movement and comfort.
3Device complexity
If manual adjustment mechanism is used, then device complexity is reduced, but productivity and ease of operation deteriorate
Solution Approach 1:
The footrest enables self-service adjustment where the user's body weight and natural foot movements are utilized to operate the adjustment mechanism. The pedal system allows one-foot operation where the user can adjust the height by pressing the pedal, leveraging their own weight to drive the rack and catch mechanism, thereby achieving quick adjustment without complex motors or additional power sources.
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
Enables precise, effort-efficient height adjustments in small steps with reliable load-bearing capability, maintaining selected heights even under heavy loads and allowing for a compact design that does not obstruct foot movement.
Implementation Method 1
the catch and the rack are mutually engaged in a direction transverse (perpendicular) to the direction in which the teeth project from a base... the catch projects into a space between the rack and the counter surface, so that the catch is reliably held in engagement with the teeth even if resultant forces urge the catch away from the rack
Implementation Method 2
the footrest height is adjusted by changing the angle of mutually crossing leg structures under the treadboard
Data Source
Figure 1
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Figure 3
AI summary
A height adjustable footrest with a treadboard part (1), a support structure (2) and an adjustment structure (3). The support structure has leg structures (4, 5), hinged to the treadboard part (1) about spaced apart hinge axes (16, 17), crossing each other and hinged to each other or to a base part. The adjustment structure (3) has a toothed rack (25, 26) and a catch (27) for engagement with the rack (25, 26) in selectable positions. The catch (27) and/or the rack (25, 26) is displaceable transverse to the longitudinal direction (28) of the rack between a protruded position in which the catch (27) engages the rack (25, 26) and a retracted position in which the catch (27) and the rack (25, 26) are released. The teeth (30) of the rack (25, 26) each project transverse to the engagement directions (29). In the protruded position, the catch (27) projects between the rack (25, 26) and the counter surface (26, 25) and contacts a counter surface (26, 25) facing the rack (25, 26).