Unitary Rear Frame for ZTR Mower Engine Mounting
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Solution Overview
Problem
The existing mounting structures for rear-mounted engines and hydrostatic transmissions in zero turning radius (ZTR) mowers are labor-intensive and costly due to the high number of parts requiring welding, which complicates assembly and inspection.
Innovation Solution
A unitary rear frame made of stamped sheet metal with horizontal mounting surfaces and side panels, allowing for the secure attachment of the engine, hydrostatic transmissions, and other components using threaded fasteners without welding, simplifying the assembly process and reducing labor costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional mounting structures with multiple parts and welding are used, then secure connection of engine and hydrostatic transmissions is achieved, but labor intensity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines multiple separate mounting parts (mounting plates, supporting panels, brackets) into a single unitary rear frame structure. This consolidation eliminates the need for numerous welds between separate components while maintaining structural integrity through integrated design with horizontal mounting surfaces and side panels that depend downwardly therefrom.
Solution Approach 2:
The unitary rear frame serves multiple functions simultaneously: it provides structural support for the engine, mounting surfaces for hydrostatic transmissions, attachment points for other rear-mounted components, and structural rigidity for the overall mower assembly. This multi-functionality replaces what previously required multiple specialized parts.
2Reliability
If multiple welding operations are performed to assemble mounting structures, then component security is improved, but assembly time and labor costs increase
Solution Approach 1:
By consolidating multiple welded components into one unitary structure manufactured as a single piece, the patent eliminates numerous welding operations during assembly. The unitary rear frame arrives pre-manufactured with all structural integrity already established, allowing direct bolting of components without intermediate welding steps.
Solution Approach 2:
The unitary rear frame is manufactured complete with all structural features (horizontal mounting surfaces, side panels, reinforcement ribs) before delivery to the assembly line. This preliminary formation of the complete structure eliminates the need for assembly workers to perform welding operations, transferring the manufacturing complexity to the fabrication stage where it can be more efficiently controlled.
3Reliability
If traditional multi-part mounting structures are used, then component support is adequate, but inspection complexity and time increase
Solution Approach 1:
The patent consolidates multiple separate mounting components into a single unitary rear frame, reducing the number of interfaces and joints that require inspection. Instead of examining numerous welds between separate parts, inspectors need to verify the integrity of one monolithic structure, significantly simplifying the inspection process while maintaining or improving structural reliability.
4Ease of manufacture
If stamped sheet metal unitary frame is used, then manufacturing cost and labor are reduced, but mounting surface availability must be sufficient
Solution Approach 1:
The patent utilizes the vertical dimension by having side panels depend downwardly from the horizontal mounting surfaces. This three-dimensional configuration maximizes the use of available space, providing multiple mounting surfaces at different elevations and locations without increasing the horizontal footprint, thereby accommodating engine, hydrostatic transmissions, and other components.
Data Source
AI summary
A unitary rear frame mounting an engine and hydrostatic transmissions to the rear of a ZTR mower is disclosed. The unitary rear frame includes a lower mounting surface supporting the engine, an upper mounting surface above and forward of the lower mounting surface; a wall extending between the upper and lower mounting surfaces; and a pair of integral side panels depending downwardly from the upper mounting surface and extending forwardly of the wall. Each side panel may have a side pocket for mounting a hydrostatic transmission thereto.