Single Rear Axle Fire Truck Outrigger Stability
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Solution Overview
Problem
Traditional quint configuration fire trucks require a tandem rear axle to increase the horizontal reach and vertical extension height of aerial ladders, leading to increased weight, reduced maneuverability, and higher manufacturing costs.
Innovation Solution
A quint configuration fire apparatus with a single rear axle and a set of outriggers and a stability foot, allowing the aerial ladder assembly to achieve a horizontal reach of at least 100 feet and a vertical extension height of up to 105 feet without the need for a tandem rear axle, thereby reducing weight and cost while maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a tandem rear axle is used to increase horizontal reach and vertical extension height of the aerial ladder, then the reach capabilities are improved, but the vehicle weight increases and maneuverability decreases
Solution Approach 1:
The patent transitions from a two-axle configuration to a three-point support system (single rear axle plus outriggers), adding a dimensional aspect to weight distribution. The outriggers extend laterally to create a wider support base, effectively using spatial dimensionality to enhance stability without increasing vertical weight capacity requirements
Solution Approach 2:
The outriggers are deployable components that transform the vehicle's support structure dynamically. When retracted, the vehicle maintains mobility with a single rear axle; when extended, the outriggers provide additional support points to handle the increased moments generated by extended ladder operations
2Strength
If a tandem rear axle is used to support the aerial ladder weight, then the structural capacity is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The support function is segmented between the single rear axle (handling vertical loads) and the outriggers (handling lateral stability and moment resistance). This segmentation allows each component to be optimized for its specific function rather than requiring a complex tandem axle system to handle all loads simultaneously
Solution Approach 2:
The outriggers act as intermediary elements between the vehicle chassis and the ground, providing additional support points that reduce the burden on the single rear axle. These intermediaries distribute the structural demands across multiple contact points without requiring a second rear axle
3Adaptability or versatility
If a tandem rear axle is used to achieve extended reach, then the operational capability is improved, but the vehicle maneuverability deteriorates
Solution Approach 1:
The support structure transitions from a fixed tandem axle configuration to a dynamic system where outriggers can be deployed only when needed for extended operations. During normal driving and maneuvering, the outriggers remain retracted, preserving the vehicle's inherent maneuverability with a single rear axle
Data Source
AI summary
A quint configuration fire apparatus includes a chassis, a body assembly coupled to the chassis and configured to receive a ground ladder, a fire hose, a pump, and a water tank, a ladder assembly including a plurality of extensible ladder sections, the ladder assembly having a proximal end that is coupled to the chassis, a single front axle coupled to a front end of the chassis, a single rear axle coupled to a rear end of the chassis, a single set of outriggers coupled to the chassis and positioned forward of the single rear axle, and a stability foot coupled to the chassis and positioned rearward of the single rear axle. The ladder assembly is extensible to provide a horizontal reach of at least 100 feet.