Tarp Bow Retention Apertures for Truck Cargo Box
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Solution Overview
Problem
Existing tarpaulin systems for long bed open-top truck trailers are prone to damage and failure when transporting loads like grain or sand, as the pressure causes side walls to bow outward, leading to damage or breakage of bows and retention components.
Innovation Solution
The design features a cargo box with apertures in the side walls that allow the ends of the tarpaulin bows to slide perpendicular to the side walls' longitudinal axes, reducing strain on the bows by providing a loose fit within oblong or elliptical bores, which are reinforced and aligned with markers for correct orientation, enabling the bows to move freely without additional strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bows are tightly secured in recesses or retaining rings to prevent movement, then the bows are firmly retained in place, but the bows are prone to damage or breakage when side walls bow outward under load pressure
Solution Approach 1:
The aperture is designed to be larger than the bow end cross-section, allowing the bow end to move dynamically within the aperture as the side walls bow outward under load. This dynamic clearance prevents the rigid constraint that causes breakage, while the aperture still provides sufficient retention to keep the bow in place during normal operation.
2Strength
If the aperture size is increased to allow bow movement, then the bows can accommodate side wall bowing, but the bows may become loose or disengage from the side walls
Solution Approach 1:
The aperture provides local clearance in the critical lateral direction to accommodate wall bowing, while maintaining local retention through the aperture's boundaries. The aperture dimensions are specifically designed to provide just enough clearance for movement while preventing complete disengagement, creating a balanced local condition that satisfies both requirements.
3Reliability
If the bows are rigidly secured to prevent any movement, then the bows maintain fixed position, but the rigid constraint causes damage when side walls deflect under grain or sand pressure
Solution Approach 1:
The aperture design incorporates beforehand cushioning by providing clearance space that absorbs the stress of wall bowing before it can reach the bow ends. This pre-built tolerance zone prevents the harmful transmission of wall deflection forces to the bows, protecting them from breakage while maintaining adequate retention.
Data Source
AI summary
An open-top cargo box for a truck trailer that is selectively coverable with bow-supported tarpaulin system. The cargo box has an interior cavity defined by front and rear walls connected together by a pair of longitudinally extending side walls. Each side wall has an upper horizontal surface defining a plurality of spaced-apart apertures therein. Each aperture has a first cross-sectional shape and a first size. The bows that support the tarpaulin include vertically oriented ends, each of which has a second cross-sectional shape and a second size. The second shape and size of the ends of the bows is smaller than the first shape and size of the apertures. Consequently, if the side walls of the cargo box spread apart under pressure exerted by a load carried in the cavity, the ends of the bows slidably move within the apertures in the side walls in a direction substantially perpendicular to the longitudinal axes of the side walls. The side walls may be reinforced proximate the apertures. Alternatively, each aperture is formed as a bore of an insert that is tightly received in any one of a plurality of holes in the upper surface of the side walls. The inserts may include markers on an outer surface thereof to enable the bore to be correctly aligned relative to the longitudinal axis of the side wall. Preferably, the apertures are oblong or elliptical in shape and the ends of the bows are circular in cross-section so that the ends may move from side to side within the apertures.