Deployable Service Step for Cab-Over Engine Trucks

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Solution Overview

Problem

In cab-over-engine trucks, accessing the driver's cab while servicing the engine is challenging due to the need to tilt the cab, which can be dangerous and lacks accessible steps, and traditional fixed steps can harm aerodynamics.

Innovation Solution

A deployable service step structure that stows under the vehicle and deploys when the cab is raised, maintaining a level orientation to provide safe access while avoiding aerodynamic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If fixed steps are provided on the cab, then access to the cab is improved, but aerodynamic performance deteriorates

Engineering Contradiction:
Improveaccess to cabVSAvoidaerodynamic performance
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The service steps are designed as movable structures that can be deployed and stowed. When the cab is in the service position, the steps deploy to provide access; when the cab is in the normal driving position, the steps stow to minimize aerodynamic interference. This dynamic configuration resolves the contradiction between providing access and maintaining aerodynamic performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The service steps are divided into multiple segments or sections that can independently deploy and stow. This segmentation allows the steps to be positioned only when needed (when the cab is in service position) and retracted otherwise, providing access functionality without continuous aerodynamic penalty.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the cab is tilted to expose the engine, then access to the engine is improved, but safety and accessibility to the cab deteriorate

Engineering Contradiction:
Improveaccess to engineVSAvoidsafety in cab
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The cab is designed with dynamic positioning capability, allowing it to be tilted for engine access while maintaining a generally level orientation. The service steps dynamically deploy when the cab is in the service position to provide safe access, and stow when the cab returns to normal position, ensuring safety throughout the operation.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If the service steps are stowed under the vehicle body, then aerodynamic performance is improved, but access to the cab when raised deteriorates

Engineering Contradiction:
Improveaerodynamic performanceVSAvoidaccess to raised cab
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The service steps are designed as deployable structures that transition from a stowed position (when not needed) to a deployed position (when the cab is raised for service). This dynamic behavior ensures aerodynamic performance is maintained during normal driving while access to the raised cab is provided during engine service operations.

Inventive Principle:
Principle #15Dynamics

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 safe and accessible movement within the raised cab position without compromising aerodynamics, as the steps deploy only when needed and retract when not in use.

Implementation Method 1

the service step structure is configured to be stowed interior to an exterior body of the vehicle and deployed when the cab is raised

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 2

A system of control linkages deploys the service steps when the cab is being raised and stow the steps when the cab is again being lowered

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentEP3055189B1Self-deploying service step
Publication Date: 2018.08.15 PACCAR INC
  • EP3055189B1 patent drawingFigure 1
  • EP3055189B1 patent drawingFigure 2
  • EP3055189B1 patent drawingFigure 3

AI summary

A cab-over-engine vehicle is described wherein the cab is supported in a level orientation on the vehicle's chassis. A cab repositioning system raises the cab while maintaining the cab in the level orientation, thus exposing the engine to be worked on. A service step structure that is hidden within the exterior body when the cab is over the engine is deployed when the cab is raised. The service step structure is connected to the underside of the cab such that the service step structure swings down and away from the exterior body to provide access to the raised level cab at the same time allowing access to the engine.