Pivotable Ladder Layout for Construction Machine Cab Access

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Solution Overview

Problem

Construction machines often have driver's stations that are inaccessible from ground level, requiring ascent means like ladders that need to be pivotable between positions to facilitate safe and efficient driver access.

Innovation Solution

A construction machine design featuring a pivotable ladder means attached to the undercarriage, allowing it to move between positions between the front and rear wheels, ensuring rungs remain oriented in the same direction throughout the pivoting motion, enabling easy access to the driver's station while being securely locked in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed ladder is attached to the side of the construction machine, then the structure is simple and stable, but the driver cannot access the driver's station when the machine is positioned on uneven ground or slopes

Engineering Contradiction:
Improvedriver access to driver's stationVSAvoidladder structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the ladder pivotable rather than fixed. The ladder can rotate between a retracted position (parallel to the longitudinal central plane) and an extended position (laterally outward), allowing it to adapt to different ground conditions and machine positions. This dynamic adjustment enables drivers to access the driver's station regardless of whether the machine is on level ground, slopes, or uneven terrain, while maintaining a compact form when not in use

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the ladder is positioned between the front and rear wheels, then it provides access when the machine is on level ground, but it becomes inaccessible when the machine is tilted on slopes

Engineering Contradiction:
Improvedriver access to driver's stationVSAvoidladder position adaptability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The pivotable ladder design allows the ladder to dynamically reposition itself. When the machine tilts on slopes, the ladder can rotate from its retracted position to an extended lateral position, creating a new access path that compensates for the ground tilt. This dynamic repositioning capability ensures driver access is maintained across various terrain conditions

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent transitions the ladder from a single-position (between wheels) arrangement to a multi-position system by adding the lateral extension capability. The ladder can now access the driver's station from two different spatial dimensions: longitudinally between the wheels on level ground, or laterally outward when the machine is tilted, providing versatile access paths

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If the ladder is made pivotable to adapt to different positions, then driver access is improved, but the structural complexity and potential instability increase

Engineering Contradiction:
Improveladder position flexibilityVSAvoidladder stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The pivotable ladder is designed with controlled mobility rather than free movement. The ladder rotates on a pivot axis and can be positioned in specific configurations (retracted parallel to central plane or extended laterally), providing adaptability while maintaining structural stability in each position. The controlled dynamic design prevents unwanted movement while enabling necessary position changes

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Instead of making the entire ladder structure complex and rigid to maintain stability in all positions, the patent inverts the approach by using a simple pivot mechanism that allows controlled movement. The stability is achieved not through complex rigid structures but through the simplicity and reliability of the pivot joint that constrains movement to specific, stable positions

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3621851B1A construction machine having an ascent means
Publication Date: 2024.01.24 CATERPILLAR INC
  • EP3621851B1 patent drawingFigure 1
  • EP3621851B1 patent drawingFigure 2
  • EP3621851B1 patent drawingFigure 3

AI summary

A construction machine (1) comprising an upper carriage (2), an undercarriage (3), and an ascent means (9), wherein the upper carriage (2) features at least one chassis (6), which comprises one front pair of wheels (7) and one rear pair of wheels (8), the upper carriage (2) features a driver's station (5), and the ascent means (9) features a ladder means (10), which ladder means (10) is pivotable between a first position, in which the ladder means is arranged between the front pair of wheels (7) and the rear pair of wheels (8), and a second position, in which the ladder means (10) is attached to the undercarriage (3) laterally adjacent to the front pair of wheels (7).