Influence of Scrub Radius on Steering Dynamics, Bearing Durability and Wheel-End Packaging in Heavy Commercial Vehicles

2026-01-0831

To be published on 09/14/2026

Authors
Abstract
Content
Front axle geometry is a critical determinant of vehicle performance in heavy commercial vehicles (HCVs), directly influencing steering feel, component life, and maintenance costs. This paper investigates the effects of increasing scrub radius—defined as the lateral distance between the tire contact patch center and the steering axis intersection with the ground—on steering dynamics, durability, and packaging. A larger kingpin offset generating a positive scrub radius improves steering leverage and reduces steering torque, particularly beneficial for power-assisted steering systems. However, its broader implications for wheel-end design require detailed evaluation. High-fidelity multi-body dynamics models, validated through instrumented vehicle testing, were employed to quantify these effects under diverse scenarios, including low-speed maneuvering, high-speed lane changes, and severe braking. Results indicate that a controlled increase in scrub radius (10–20 mm) reduces steering torque by up to 15% during low-speed operations, enhancing driver comfort. From a durability perspective, the altered load path redistributes lateral forces across bearing rollers, improving stress uniformity and predicting a 20–25% increase in calculated bearing life (L10) under high-frequency steering cycles. Additionally, outward displacement of the steering axis creates valuable packaging space, enabling integration of larger S-cam brake assemblies, advanced hub units, and thermal management components without increasing wheel size. Trade-offs such as tire wear, brake torque steer, and steering feedback were analyzed to establish safe design limits. The paper concludes with design guidelines correlating optimal kingpin offset and scrub radius with specific duty cycles—urban delivery versus long-haul—providing a validated framework for developing robust, low-maintenance steering systems and efficient wheel-end designs that improve uptime, reduce operating costs, and enhance driver comfort.
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Citation
Pandiyan, M. and Saxena, S., "Influence of Scrub Radius on Steering Dynamics, Bearing Durability and Wheel-End Packaging in Heavy Commercial Vehicles," Brake Colloquium & Exhibition - 44th Annual, Palm Desert, California, United States, September 20, 2026, .
Additional Details
Publisher
Published
To be published on Sep 14, 2026
Product Code
2026-01-0831
Content Type
Technical Paper
Language
English