Single-Rear-Axle Quint Fire Truck With Outrigger Stability
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Solution Overview
Problem
Traditional quint configuration fire trucks are heavy, difficult to maneuver, and expensive due to the addition of weight to increase the horizontal reach and vertical extension height of the aerial ladder, often requiring a tandem rear axle.
Innovation Solution
A quint configuration fire apparatus with a single rear axle supporting a ladder assembly that extends to 95 feet vertically and 90 feet horizontally, utilizing a stability system with outriggers and a stability foot to support a tip load of at least 750 pounds, eliminating the need for a tandem rear axle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If weight is added to increase horizontal reach and vertical extension height of the aerial ladder, then the reach and height are improved, but the vehicle becomes heavier and more difficult to maneuver
Solution Approach 1:
The patent employs outriggers that extend laterally from the vehicle to provide counterbalancing support. These outriggers create a stable base that counteracts the weight and reach demands of the aerial ladder, allowing the ladder to extend horizontally and vertically without requiring additional vehicle weight. The outriggers effectively serve as temporary counterweights distributed to the ground, enabling the aerial apparatus to achieve greater reach while maintaining vehicle maneuverability.
2Strength
If a tandem rear axle is added to carry the weight, then the load capacity is improved, but the vehicle complexity and manufacturing cost increase
Solution Approach 1:
The outriggers are deployed in advance before the aerial ladder is extended to its full capacity. By establishing the stable support base beforehand, the system prepares the ground contact points to bear the loads that will be generated during ladder operation. This preliminary action allows the single rear axle to operate within its weight rating while still supporting the full load capacity needed for extended reach operations.
3Stability of the object's composition
If a tandem rear axle is added to support the aerial ladder, then the stability is improved, but the ease of operation deteriorates
Solution Approach 1:
The outrigger system transitions from a retracted state during vehicle travel to an extended state during aerial ladder operations. This dynamic configuration allows the vehicle to be maneuverable when the outriggers are stowed, and becomes highly stable when the outriggers are deployed. The system adapts its stability characteristics based on operational phase, providing ease of operation during transport and maximum stability during ladder extension without requiring a fixed tandem axle configuration.
Data Source
AI summary
A quint configuration fire apparatus includes a chassis defining a longitudinal axis, a front axle, a single rear axle having a gross axle weight rating of less than or equal to 33,500 pounds, a body having storage configured to receive a ground ladder and a fire hose, a pump, a water tank, a ladder assembly having a proximal end supported by the chassis proximate a rear end of the chassis, and a stability system. The quint configuration fire apparatus supports a tip load of at least 750 pounds applied to a distal end of the ladder assembly while the ladder assembly is (a) extended to a horizontal reach of at least 90 feet and (b) rotated between a plurality of operating orientations.