Off-Road Steering Rack Assembly With Billet Housing Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Steering rack assemblies in off-road vehicles often fail due to catastrophic fractures in the cast aluminum housing, especially when used with large tires in challenging off-road conditions, indicating a need for improved materials and support features.
Innovation Solution
The steering rack assembly is fabricated with a housing made from billet aluminum for increased strength and durability, and supported by precision bushings that distribute contact forces uniformly, eliminating the need for preload adjusters and minimizing rack deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cast aluminum housing is used to facilitate mass production and reduce cost, then manufacturing ease and cost are improved, but housing strength and durability deteriorate under extreme off-road conditions
Solution Approach 1:
The patent changes the material parameter of the housing from cast aluminum to billet aluminum. This parameter change maintains ease of manufacture through CNC machining while dramatically improving housing strength and durability to withstand extreme off-road conditions and large tire applications.
2Ease of operation
If clearance fit bushings are used to facilitate assembly and allow adjustment, then assembly ease is improved, but rack deflection increases under load
Solution Approach 1:
The patent applies precision bushings with tight tolerances at specific locations where the rack contacts the housing. This localized precision support reduces rack deflection under load while maintaining ease of assembly through the bushing design that allows press-fit installation.
3Adaptability or versatility
If preload adjuster is used to set gear mesh, then adjustment capability is improved, but housing strength deteriorates due to stress concentration
Solution Approach 1:
The patent removes the preload adjuster mechanism from the housing structure. Instead, gear mesh is set through precision machining of the rack and pinion components themselves. This extraction eliminates the stress concentration point that caused housing fractures while maintaining the ability to achieve proper gear engagement.
4Device complexity
If minimal support within housing is used to facilitate mass production, then manufacturing complexity is reduced, but reliability deteriorates under extreme loads
Solution Approach 1:
The patent incorporates precision bushings into the housing design that are pre-positioned to provide optimal support locations for the rack. These bushings are integrated into the housing structure during manufacturing, providing enhanced reliability under extreme loads without significantly increasing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of billet aluminum and precision bushings significantly enhances the stability and shock load tolerance of the steering rack assembly, reducing the likelihood of catastrophic failures and ensuring the system remains strong under extreme off-road conditions.
Implementation Method 1
The bushing on the pinion side is a long oil impregnated bronze bushing that features a cut out for the pinion to slip though. The result is that the rack bar is supported on both sides of the pinion as well as directly behind the mesh of the rack and pinion.
Implementation Method 2
At least one of the bushings may be formed from an oil impregnated bronze sleeve, a plain bearing, or a sleeve bearing.
Data Source
AI summary
An improved steering rack assembly includes a rack housing and pinion case having a first bushing disposed over the rack at a location corresponding to the pinion. A cut-out in the bushing allows contact between the pinion and the rack while supporting the rack on either side of the pinion.