All-Wheel Steering Linkage for Riding Mower Maneuverability
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Solution Overview
Problem
Traditional zero-radius-turning (ZRT) riding mowers face limitations such as potential turf damage from wheel slip and a limited turning center, which restricts maneuverability, especially in lawns with obstacles and tight spaces.
Innovation Solution
The implementation of an all-wheel steering (AWS) system in riding lawn mowers, featuring a frame with pivotally coupled front and rear wheel assemblies, tie rods, and a steering actuator responsive to a steering input device, allowing for independent control of each wheel for enhanced maneuverability and reduced turf damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ZRT steering is used with drive wheels only, then the turning center is limited to the drive wheel axis, but the vehicle can achieve zero-radius-turning capability
Solution Approach 1:
The steering system is segmented into independent control for each wheel (front left, front right, rear left, rear right), allowing individual wheel angle adjustment. This segmentation enables the turning center to be positioned at various locations by coordinating different wheel steering angles, rather than being fixed at the drive wheel axis.
Solution Approach 2:
The patent implements dynamic steering where the steering angles of front and rear wheels can be independently adjusted based on operating conditions. The system transitions between different steering modes (e.g., all wheels steering in same direction for tight turns, opposite directions for other maneuvers), making the turning center position variable rather than fixed.
2Productivity
If ZRT mowers use differential wheel rotation for turning, then sharp turns can be executed, but wheel slip may occur causing turf damage
Solution Approach 1:
By providing independent steering control for each wheel rather than relying solely on differential drive wheel rotation, the system can distribute turning forces more evenly across all four wheels. This reduces the likelihood of wheel slip on any single wheel, thereby minimizing turf damage while maintaining sharp turning capability.
Solution Approach 2:
The front caster wheels act as intermediaries that can be steered to assist in the turning maneuver. By engaging the front wheels in steering, the system reduces the burden on the drive wheels, distributing the turning effort and reducing slip-induced turf damage.
3Adaptability or versatility
If all wheels are made steerable with linkage assemblies, then maneuverability is enhanced, but the device complexity increases
Solution Approach 1:
The patent merges the steering functions of front and rear wheels into a coordinated system where the linkage assembly integrates multiple control functions. The steering actuator controls both front and rear wheel angles through the linkage, reducing the number of independent actuators needed while achieving all-wheel steering capability.
Solution Approach 2:
The linkage assembly serves multiple functions: it connects the steering actuator to both front and rear wheels, enables coordinated steering of all four wheels, and allows the system to operate in different steering modes (all wheels same direction, opposite directions, or selective steering). This multi-functionality reduces overall system complexity despite the enhanced maneuverability.
Data Source
AI summary
An all-wheel steering system and vehicle, e.g., riding lawn mower, incorporating the same. The system may include a linkage system that operatively connects the vehicle wheels for simultaneous turning. The system, in one embodiment, includes a power steering unit having fixed or variable output for a given steering input. The system may further include a mechanism for reducing speed based upon mower steering angle.