Fundamentals of Steering Systems
I.D. # C0716 Duration 2 Days

Design and development of a modern steering system influences vehicle response, driver controllability, comfort, safety and fuel economy. In this interactive seminar, participants will analyze the steering system, from the steering wheel to the road wheel. The seminar will cover the anatomy and architecture of the lower steering system (wheel end suspension geometry, linkages and steering gear), its effect on vehicle response, and how a force at the contact patch is translated to a torque in the steering wheel. The anatomy and architecture of the upper steering system (steering column and intermediate shaft), including the topic of non-uniformity and the role of the upper steering in the occupant protection system will also be explored.

Significant time will be devoted to the generation of power assist, either by way of a conventional hydraulic power steering (HPS) or electrically power assisted steering (EPAS). Topics include system anatomy/architecture as well as the effect of the system on fuel economy. The seminar will finish with a discussion of common steering objective tests and how the kinematics, compliances, friction and power assist affect steering response and torque feedback. Students will have the opportunity to participate in exercises throughout the seminar, culminating in a final project where they will calculate an assist curve for both a HPS and an EPAS system.

This course has been approved by the Accreditation Commission for Traffic Accident Reconstruction (ACTAR) for 12 Continuing Education Units (CEUs). Upon completion of this seminar, accredited reconstructionists should contact ACTAR, 800-809-3818, to request CEUs. As an ACTAR approved course, the fee for CEUs is reduced to $5.00.
Learning Objectives
By attending this seminar, you will be able to:
  • Identify common steering and suspension system architectures
  • Compare and contrast different types of steering gears
  • Describe the function of the steering column and intermediate shaft subsystem
  • Describe the influence of system tuning on steering response and torque feedback
  • Compare and contrast different types of power assist systems
  • Describe the effect of power steering on fuel economy
  • Calculate important parameters that affect steering response and torque feedback
Who Should Attend
This seminar is designed for automotive engineers in the vehicle dynamics, chassis, suspension, steering and chassis controls fields who work in product design, development, testing, simulation or research.
Prerequisites
Participants must have a working knowledge of the fundamentals of vehicle dynamics acquired through sufficient work experience or by participating in seminars such as SAE's Vehicle Dynamics for Passenger Cars and Light Trucks (ID# 99020), Chassis and Suspension Component Design for Passenger Cars and Light Trucks (ID# 95025) or Advanced Vehicle Dynamics for Passenger Cars and Light Trucks (ID# C0415).
Seminar Content
DAY ONE
  • Introduction
    • Elements of the steering system
    • Coordinate systems
  • The Lower Steering System
    • Kingpin axis -- Front versus rear steer; Caster angle and kingpin inclination; Caster trail and scrub radius; Steer arm
    • Class exercise - Calculate moment about the kingpin axis for cornering and parking loadcases
    • Linkages/steering geometry -- Rack and pinion; Haltenberger; Parallel linkage
    • Steering gear anatomy and architecture -- Rack and pinion; Recirculating ball
    • Friction and compliances
    • Class exercise - Calculate pinion torque for cornering and parking loadcases
  • The Upper Steering System (steering column & intermediate shaft)
    • Anatomy and architecture
    • Non-uniformity
    • Sources of friction and torsional compliance
    • Role of the upper steering system in the occupant protection system
DAY TWO
  • Power Assist Systems
    • Conventional hydraulic power assist
    • Electro-hydraulic assist
    • Electric power assisted steering
    • Speed sensitive steering
  • Vehicle Level Considerations
    • Steering response -- Effect of steering ratio on response gain
    • Steering feel/torque feedback -- Common steering tests and metrics; Effect of friction, compliances, and steering column non-uniformity
    • Class exercise - Calculate a power steering assist curve for hydraulic or electric power assisted steering system
    • Error states (nibble/wheelfight, pull/drift)
    • Power steering system effect on fuel consumption
Instructor(s): Timothy Drotar
Timothy Drotar is currently a product development engineer at Ford Motor Company where he specializes in chassis systems and vehicle dynamics for passenger cars and light trucks. He also has developed engineering training in suspension and steering. Previously, he worked for Saturn Corporation in product engineering. Tim is a member of the Course Industry Advisor Board for Chassis Systems Design at Kettering University, and a member of SAE and SCCA. He holds a B.S. in Mechanical Engineering from Lawrence Technological University and a M.S. in Mechanical Engineering from the University of Michigan.
Testimonial

"Very informative class on everything that goes into designing a steering system from the ground up."
Cory C. Cousineau
Development Engineer
EMP-Engineered Machined Products, Inc.
Fees: $1265 SAE Members*: $1005 - $1135
* The appropriate SAE Member discount will be applied through the Registration process.  Discounts vary according to level of membership: Elite Member 20%; Premium Member 15%; Classic Member 10%
CEU 1.3