Retractable Ladder Step Assembly for Ground Collision Protection
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Solution Overview
Problem
Existing ladder designs for combine harvesters do not effectively address the issue of the ladder retracting upon collision with ground obstacles, which can lead to damage and safety concerns.
Innovation Solution
A step assembly for a ladder that includes first and second siderail members pivotally mounted for movement between a suspended use position and a retracted position, with a step that is movable between an unlocked and locked position, allowing it to swing laterally with the siderail members in response to a retracting force while locking in place for use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ladder is designed with fixed steps for stable use, then the usability and safety during normal operation is improved, but the ladder cannot retract laterally when colliding with ground obstacles causing damage risk
Solution Approach 1:
The step assembly is designed with dynamic characteristics, allowing it to transition between a locked position (for stability during use) and an unlocked position (for lateral retraction during collision). The yieldable biasing mechanism enables the step to automatically shift positions based on applied forces, providing both stability when needed and flexibility to absorb impact when colliding with obstacles.
2Stability of the object's composition
If the step is designed to be locked to the siderail members for stable use, then the ladder structure rigidity is improved, but the ability to swing laterally in response to retracting force is lost
Solution Approach 1:
The connection between the step and siderail members is designed to be conditionally rigid or flexible. When locked, the connection provides structural rigidity for stable use. When unlocked, the connection allows lateral swinging motion in response to retracting forces. The yieldable biasing mechanism controls the transition between these two states based on applied forces.
Solution Approach 2:
The mechanical properties of the step-siderail connection are changed based on operational conditions. The yieldable biasing mechanism alters the connection state from rigid (locked) to flexible (unlocked) in response to force magnitude, enabling the structure to adapt its stiffness parameter dynamically between use and collision scenarios.
3Object-affected harmful factors
If the step assembly is made retractable for collision protection, then the damage prevention capability is improved, but the usability and safety during normal operation may be compromised
Solution Approach 1:
The step assembly automatically performs the retraction function without external control systems. When a retracting force is applied during collision, the yieldable biasing mechanism automatically unlocks and allows lateral movement. During normal use, the biasing mechanism maintains the locked position, ensuring stability and safety without requiring user intervention.
Solution Approach 2:
The yieldable biasing mechanism is pre-configured to maintain the step in a locked position during normal operation, preventing accidental retraction. The mechanism is designed with specific force thresholds that must be exceeded to unlock, ensuring that only genuine collision forces (not normal use forces) will trigger the retraction action.
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 step assembly effectively retracts laterally to prevent damage from ground collisions while ensuring the ladder remains usable and safe for access to elevated areas.
Implementation Method 1
The step is yieldably biased to the unlocked position
Data Source
AI summary
A step assembly for use with a ladder comprises a first siderail member, a second siderail member, and a step. The first and second siderail members are mounted for pivotal movement about respective pivot axes between a suspended use position and a retracted position. The step has an unlocked position and a locked position. The step is yieldably biased to the unlocked position. In the unlocked position, the step is unlocked relative to the first and second siderail members enabling the step to swing with the first and second siderail members from the suspended use position to the retracted position. In the locked positioned, the step is locked to the first and second siderail members against relative pivotal movement between the step and the first and second siderail members to keep the first and second siderail members in the suspended use position for use of the step.