International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072

Selection & Design Procedure of Steering System of Formula Student

(FSAE) Car
Kishor C. Budhale1, Prathmesh Mahesh Daphale 2, Souarabh Ravsaheb Chougule 3,
Hari Ananda patil 4, Ashitosh Anil Mali 5
1Asst. Professor, Dept. of Mechanical Engineering, D.Y. Patil College of Engg. & Tech., Kolhapur
2,3,4,5Student, Dept. of Mechanical Engineering, D.Y. Patil College of Engg. & Tech., Kolhapur
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Abstract – The main objective of this paper is to give steering mechanism reduces the friction and also reduces
detailed review of Formula Student Vehicles steering the steering effort and help to take more sharp turns.
mechanism. Realistic approach of geometry selection for
steering mechanism is followed by designing with the help of
Solid Works 2017. The steering ratio, turning radius,
steering efforts, front wheels turning angles and Ackermann
percentage are optimized in Lotus Shark and ADDAMS. The
goal of designing and optimizing the steering mechanism is
to provide good directional stability and full control over the
vehicle even on the sharp hair pin turns. All the design obeys 2.3 Anti-Ackerman Steering Gear Mechanism
the rules stated by the FSAE rulebook and FORMULA
BHARAT rulebook 2019.
The Anti-Ackerman steering is similar to Ackerman steering
only difference is that the steering is operated from front
Key Words: Ackermann steering, Steering ratio, C-factor,
side of the wheels. The steering provides more slip angles
Rack position
and help to take sharp turn.
1. INTRODUCTION

The steering system of formula SAE car is one of the

important task. As the steering help the driver to control
vehicle however he wants. The steering provides good
stability to vehicle on road. It is combine effect of the all
linkages by efforts gives by driver to wheels which results to
high speed on the track.
So as to design and manufacture the steering system for
Formula SAE vehicle as per the rule book of SUPRA SAE India
2018and Formula Bharat 2019. The steering provide pure 3. SELECTION OF STEERING MECHANISM
rolling motion to wheel and fulfil the requirements of
steering to take the sharp turn on the track. 3.1 Davis or Anti-Ackerman steering system would
difficult to steer at lower speed. By using Ackerman
2. STEERING GEAR MECHANISM Steering mechanism, it helps to reduce the weight of
the steering column and provides good directional
2.1 Davis Steering Gear Mechanism stability. So, the Ackerman steering mechanism si
selected.
In Davis steering there are sliding guides attached to rack
setup and these guides slide on the rods extended from wheel
4. STEERING GEOMETRY PARAMETER
hub king pin. Davis steering is operated from front side
wheels. This mechanism causes friction between rod and
guides, thus increase steering effort. As per FSAE Rule book wheelbase should be minimum
1525mm, & other following required parameters select by
2.2 Ackerman Steering Mechanism the FSAE guidelines.

In Ackerman steering, the sliding pairs of Davis steering

are replaced by all the turning pairs. Basically the Ackerman

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 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072

Table -4.1: Steering Data Which is as follows

Front track width
Factor of Safety (fs)-The recommended factor of safety is
Rear track width from 1.5 to2
Turning Radius
Inner wheel angle
Outer wheel angle Peff =

4.1STEERING RATIO Tangential force on Gear:

Steering ratio is the ratio of how much the steering wheel

turns in degrees to turn the wheel by 1 degree

Steering ratio = Turn of steering wheel in degrees Beam strength of gear (Sb)
Turn of wheel by 1 degree
= Module*face width*maximum bending load*Lewis form
Steering ratio depends on many factors like diameter of factor.
pinion, rack travel, steering wheel diameter, moment arm
length etc. This equation is known as Lewis equation.

4.2 TURNING RADIUS Sb = m*b* *Yp

From these steps the gears is designed

By changing the Ackerman setting of car the overall turning
radius of the car can be adjusted. The turning radius of the
vehicle was calculated based on ideal ackermann position to
maximum. The car had wheelbase of 1600mm and the M=
required turning radius up to 3.7m which is reasonable for
expected hair pin turns on the formula auto cross race track.
4.5. RACK Position:
4.3. C-FACTOR
Rack is mounted behind the front wheel center line as per
C-Factor is defined as length in mm travelled by rack for 360 the geometrical, ergonomics and driver egress viewpoint.
degree rotation of pinon. Rack position is optimized by observing the changes in
steering radius, inner wheel and outer wheel angles as per
C-Factor = Rack travel the requirements.
One pinon rotation
Lotus shark software: -the Lotus Suspension Analysis
4.4. RACK & PINION DESIGN SHARK module is a suspension geometric and kinematic
modelling tool, with a user- friendly interface which makes it
easy to apply changes to proposed geometry and
Rack & Pinion starts with the first basic step i.e. selection of
instantaneously assess their impact through graphical
the material which leads that improper material selection
results. Lotus shark software gives instantaneous results of
which cause failure.
inside angle (in degree) for a particular rack shift.
In the design of gears, it is required to decide the number of
Rack shift or rack travel per rotation is the horizontal
teeth on the pinion and gear. There is a limiting value to the
distance travelled by the rack gear when the pinion gear
minimum number of teeth on the pinion. While decreasing
completes one rotation.
the number of teeth, a point is reached when there is
The tangential force on the gear (Pt) interference.
Interference is non-conjugate action and results in
excessive wear, vibrations and jamming. To avoid
interference, minimum number of teeth for 20° full depth
system required is 17. Using Lewis equation, the module is
calculated. It predicted the chances of teeth interference. So,
number of teeth on gear is increased to 21. And then again
designed using Lewis equation and Buckingham equation.

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 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072

3. Final Steering System

3. CONCLUSION

Steering system used for student formula race car, different

parameters should be considered like steering parameters,
steering ratio, turning radius, C-factor. According to all these
parameters, rack position is to be selected to fulfill the all
requirement as overall analysis of Rulebook of FSAE &
Formula Bharat.

ACKNOWLEDGEMENT

The team which have more contribution to the big process to

meet the target for race car. We would like to show our
gratitude over faculty advisor. It is combination of team
spirit & huge support of faculty advisor.

REFERENCES

1) Smith, Carroll, Engineer to Win. MBI Publishing

Company, Minnesota, 1984.Vol. 2

2) Fenton, J. (1980), Vehicle Body Layout and Analysis,

Mechanical Engineering Publications Ltd. London.
Paper ID #16351

3) Smith, C. (1978), Tune to Win: The Art and Science

of Race Car Development and Tuning, Aero
Publishers, Inc. 329 West Aviation Road, Fallbrook,
CA 29028 Page no. 60-64

4) Vehicle Dynamics Terminology- SAEJ670, Revise

07-1976. 2017 IJEDR | Volume 5, Issue 3

5) William F. Milliken and Douglas L. Milliken, 1995,

“Race Car Vehicle Dynamics”, Society of Automotive
Engineers, Inc. Page no. 709-728

6) Gillespie, Thomas D., Fundamentals of Vehicle

Dynamics. Society of Automotive Engineers, Inc.,
Pennsylvania, 1992 Page no. 27-30

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