Ladder Support Structure for Single-Axle Fire Apparatus Reach
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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 their aerial ladders, leading to increased weight, difficulty in maneuverability, and higher manufacturing costs.
Innovation Solution
A support structure for a ladder assembly that includes a torque box, pedestal, and support plate, which transfers the load from the aerial ladder to the fire apparatus chassis using a single rear axle, allowing for increased vertical extension height and horizontal reach without the need for a tandem rear axle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tandem rear axle is used to increase aerial ladder horizontal reach and vertical extension height, then the load-bearing capacity is improved, but the vehicle weight increases and maneuverability deteriorates
Solution Approach 1:
The support structure is divided into multiple functional components: a torque box for mounting, a support plate with legs for load distribution, and a pedestal for vertical support. This segmentation allows each component to be optimized for its specific function while collectively achieving the required load-bearing capacity without needing a tandem axle.
Solution Approach 2:
The support plate extends horizontally with legs that engage the chassis at multiple points, distributing the load across a wider area. The pedestal provides vertical support while the torque box mounts to the chassis frame. This multi-dimensional load distribution achieves tandem-axle equivalent strength with a single axle configuration.
2Strength
If a tandem rear axle is used to support heavier aerial ladder components, then the structural strength is improved, but the manufacturing cost increases
Solution Approach 1:
The support structure merges multiple functions into a single integrated assembly: the torque box provides both mounting and structural reinforcement, the support plate distributes loads across the chassis, and the pedestal provides vertical support. This combined structure achieves the structural strength of a tandem axle system while using a single axle chassis, thereby reducing manufacturing costs.
Solution Approach 2:
The support structure components serve multiple functions: the torque box mounts the aerial ladder and reinforces the chassis mounting points, the support plate distributes loads and provides structural support, and the pedestal provides vertical elevation. This multi-functionality eliminates the need for additional axles while maintaining structural integrity.
3Length of moving object
If weight is added to increase aerial ladder horizontal reach and vertical extension height, then the performance is improved, but the vehicle weight increases
Solution Approach 1:
The support structure uses a pedestal that can be adjusted in height, allowing the aerial ladder to achieve greater vertical extension height without permanently increasing the vehicle's base weight. The dynamic adjustment capability provides extended reach when needed while maintaining a compact, lightweight configuration during transport.
Solution Approach 2:
The support plate acts as an intermediary between the torque box and the chassis, distributing the weight of the extended aerial ladder across multiple chassis attachment points. This load distribution mechanism enables greater horizontal reach and vertical extension without proportionally increasing the overall vehicle weight.
Data Source
AI summary
A support structure for a ladder assembly of a fire apparatus includes a torque box, a pedestal, and a support plate. The torque box includes a top surface defining an aperture. The pedestal has (i) a lower end received by the aperture of the torque box and (ii) an upper end configured to couple to the ladder assembly. The support plate is positioned along the top surface of the torque box. The support plate includes a first leg and a second leg. The first leg extends from a first side of the support plate and is configured to engage with a first rail of the fire apparatus. The second leg extends from an opposing second side of the support plate and is configured to engage with a second frame rail of the fire apparatus.