Rear Suspension Geometry for Toe Stability at Full Compression
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Solution Overview
Problem
Rear wheels in off-road vehicles tend to toe in or toe out during suspension travel, especially at full compression, leading to instability and loss of directional control.
Innovation Solution
A rear suspension assembly featuring a trailing arm, upper and lower radius rods, and a suspension member configured to control toe, which maintains the rear ground-engaging members in a forward-facing direction by positioning the suspension member vertically intermediate the upper and lower surfaces of the trailing arm, thereby minimizing toe change during compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a trailing arm and radius rods are used in the rear suspension assembly, then the vehicle achieves suspension travel capability, but the rear wheels exhibit toe change (toe in or toe out) during suspension travel especially at full compression
Solution Approach 1:
The suspension system is divided into multiple independent components: trailing arm for vertical motion, radius rods for lateral control, and a separate toe control link specifically dedicated to maintaining wheel orientation. This segmentation allows each component to specialize in one function, preventing the interference that causes toe change during suspension travel.
Solution Approach 2:
A toe control link is introduced as an intermediary component between the trailing arm assembly and the wheel hub/knuckle. This link acts as a mediator that actively counteracts the toe-changing tendencies of the trailing arm and radius rod configuration, maintaining proper wheel orientation throughout the suspension cycle.
2Adaptability or versatility
If the rear suspension is designed for off-road terrain capability, then the vehicle achieves enhanced terrain performance, but directional control and stability are lost during full compression rebound
Solution Approach 1:
The toe control link is pre-configured with specific geometry and mounting positions that establish the correct wheel toe orientation before suspension travel begins. As the suspension compresses and rebounds during off-road operation, this pre-established configuration actively maintains proper directional alignment, preventing loss of control during the rebound phase.
3Device complexity
If a simple trailing arm configuration is used, then the device complexity is reduced, but the manufacturing precision and assembly requirements increase to control toe change
Solution Approach 1:
The toe control link is designed to automatically maintain proper wheel orientation through its geometric configuration and mechanical linkage, without requiring active control systems or complex adjustment mechanisms. The system self-regulates toe alignment throughout the suspension cycle, reducing both complexity and precision requirements compared to alternative designs.
Data Source
AI summary
A utility vehicle includes a rear suspension assembly which has a trailing arm generally extending longitudinally. Also, the rear suspension assembly includes an upper radius rod extending in a generally lateral direction relative to a centerline of the vehicle. Additionally, the rear suspension assembly includes a lower radius rod extending in a generally lateral direction relative to the centerline of the vehicle. The rear suspension assembly further includes a suspension member configured to control toe of the at least one rear ground-engaging member.