Cam-Actuated Ladder Joint for High Load and Compact Folding
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Solution Overview
Problem
Conventional folding and locking mechanisms for ladders are limited in supporting high loads, being modularly reconfigurable, and collapsing into a small package, especially for long ladders that need to reach significant heights and support heavy loads.
Innovation Solution
A rotating hinge joint mechanism with a cam element that allows two rigid members to be locked together, enabling rotation and supporting high torque, while allowing complete separation and folding into a compact size, with a spring-preloaded locking mechanism that engages only in a single rotational position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional folding and locking mechanisms are used in ladders, then the ladder can be folded and locked, but the ladder cannot support high loads and cannot collapse into an exceptionally small package
Solution Approach 1:
The ladder is divided into multiple folding sections with rotational joints, allowing it to collapse into a compact package while maintaining structural integrity. Each section can be independently folded, enabling the ladder to reduce to a small storage size while still supporting heavy loads when deployed.
Solution Approach 2:
The locking mechanism transitions between locked and unlocked states dynamically. When unlocked, the ladder sections can rotate freely for folding and collapsing. When locked, the cam element engages with the cam follower to rigidly connect sections, providing high load support capacity. This dynamic state change allows the same structure to serve both compact storage and heavy load-bearing functions.
2Force
If conventional locking mechanisms are used, then the ladder can be locked in position, but the mechanism cannot support exceptionally high torque between members
Solution Approach 1:
The cam element features a curved cam surface that works with a cam follower to create a mechanical advantage system. The curved geometry of the cam allows it to convert rotational motion into linear locking force, generating exceptionally high torque capacity between ladder sections. The cam's curved profile enables progressive engagement that distributes loads effectively across the locking interface.
Solution Approach 2:
The cam element acts as an intermediary between the manual locking action and the high torque transmission requirement. By introducing the cam mechanism as a mediator, a relatively small manual force applied to rotate the cam can generate exceptionally high locking forces through the cam's mechanical advantage, avoiding the need for complex multi-component locking systems.
3Ease of operation
If conventional locking mechanisms are used, then the ladder sections can be connected, but the mechanism requires tools for assembly and disassembly
Solution Approach 1:
The locking mechanism is designed to be self-servicing through manual operation. The cam element can be rotated by hand to engage or disengage the locking action without requiring any tools. The cam's geometry is designed so that manual rotation creates sufficient force to lock the sections reliably under heavy load, and the same manual rotation in reverse allows easy disassembly. This self-service capability maintains both ease of operation and locking reliability.
4Stability of the object's composition
If conventional locking mechanisms are used, then the ladder can maintain structural integrity, but the mechanism allows rotational play or backlash
Solution Approach 1:
The spring element applies a preliminary preloading force to the cam-follower interface before loads are applied during use. This preloading ensures that the cam and follower are already in firm contact with no clearance or backlash when the ladder is locked. The spring maintains constant pressure on the cam surface, eliminating rotational play and ensuring precise structural rigidity without requiring extremely tight manufacturing tolerances.
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 a ladder to fold into a small package, deploy to full length, and support heavy loads, while being easily assembled and disassembled by hand without tools, with zero backlash and high stability.
Implementation Method 1
A cam element provided with the female hinge element can be moved between an unlocked position in which the ladder sections can rotate with respect to each other, and a locked position in which the structure is rigid.
Implementation Method 2
A rotating hinge joint mechanism with a cam element that allows two rigid members to be locked together, enabling rotation and supporting high torque, while allowing complete separation and folding into a compact size, with a spring-preloaded locking mechanism that engages only in a single rotational position.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A ladder comprising: a first ladder section including two rails and at least two rungs, each rung extending between the two rails, the first ladder section including a first ladder section connecting end having a first ladder section locking feature; a second ladder section including at least one rail and having a second ladder section connecting end having a second ladder section locking feature; a cam element slidably disposed along a rail of a first one of the first and second ladder section connecting ends, the cam element having an internal cam surface; and a male hinge element provided on a second one of the first and second ladder section connecting ends and having a transverse connecting element having a cam follower, the transverse connecting element extending into a path along which the cam element is configured to slide along the rail such that the cam follower selectively contacts the internal cam surface; wherein sliding movement of the cam element to an unlocked position allows the first and second ladder sections to rotate relative to each other while sliding movement of the cam element to a locked position causes the first ladder section locking feature and the second ladder section locking feature to engage each other to prohibit relative rotation between the first and second ladder sections.