Rear Discharge Mower Deck with Flat Gear Power Transmission
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Solution Overview
Problem
Conventional rear discharge mowers face challenges with high belt tension leading to structural strength issues in the mower deck, noise from bevel gear mechanisms, and limited space for large diameter bevel gears, which affect the efficiency and practicality of grass clipping discharge.
Innovation Solution
A mower blade drive casing with cylindrical shaft casings and a connecting casing portion that supports blade shafts, using a power train of flat gears to transmit power, allowing for a thin mower deck and optimizing the grass-clippings discharge path by positioning the starting end closer to the front without affecting the mower deck structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power transmission belt is used to transmit power to blade shafts with the power transmission pulley positioned at a distance from the mower deck, then power transmission efficiency is improved, but the mower deck structure requires very high strength and the belt tension becomes excessively high
Solution Approach 1:
The patent transitions from a belt-driven power transmission system to a gear-based system positioned in a different spatial dimension (above the mower deck). The gear mechanism is mounted on the mower deck surface rather than悬空, eliminating the need for high-tension belts spanning large distances while maintaining effective power transmission to the blade shafts.
2Power
If bevel gear mechanisms are used to transmit power to blade shafts, then power transmission capability is improved, but noise increases and the required space for large diameter gears becomes problematic
Solution Approach 1:
The patent changes the gear type parameter from bevel gears to spur gears, fundamentally altering the meshing characteristics. Spur gears operate with parallel shafts and produce less noise compared to bevel gears, while still achieving the required power transmission capability through appropriate gear ratio selection and positioning.
3Productivity
If the grass-clippings discharge path starts closer to the front end of the mower deck, then discharge efficiency is improved, but the power transmission pulley placement becomes constrained
Solution Approach 1:
The patent extracts the power transmission mechanism from the traditional belt-pulley system and replaces it with a gear system that is independently positioned on the mower deck. This separation allows the grass-clippings discharge path to be optimized for maximum efficiency (starting at the front end) without being constrained by pulley placement, as the gear system can be positioned according to space availability rather than belt routing requirements.
Data Source
AI summary
A rear discharge mower comprising: a first shaft; a first blade that is rotated in unison with the first shaft; a second shaft that is configured to be rotated in a direction opposite from a rotational direction of the first shaft; a second blade that is rotated in unison with the second shaft, wherein a grass-clippings discharge path is formed through which grass clippings are discharged in a rearward direction from the area between the first shaft and second shaft; an enclosing casing that supports the blade shafts; and a power train that is accommodated in the enclosing casing and that transmits power to the first and second blade shafts.