It is a complete report about power assisted steering system.

1. A
Seminar Report
On
POWER STEERING SYSTEM
Submitted in partial fulfillment of requirements for the award of degree of
Bachelor of Engineering
in
Mechanical Engineering
Submitted by
XYZ
4ES12ME___
DEPARTMENT OF MECHANICAL ENGINEERING
SRINIVAS SCHOOL OF ENGINEERING
Mukka, Mangalore - 574146

2. SRINIVAS SCHOOL OF ENGINEERING
MUKKA, MANGALORE - 574146
DEPARTMENT OF MECHANICAL ENGINEERING
CERTIFICATE
This is to certify that report entitled Power Steering System is a bonafide record of
seminar presented by Mr. XYZ (4ES12ME___), in partial fulfillment of requirements for the
award of degree of Bachelor of Engineering in Mechanical Engineering from Visvesvaraya
Technological University, Belgaum during the academic year 2015-2016.
__________________ ___________________
(Mr. V. Pradeep Kamath) (Dr. Suma Bhat)
Seminar Coordinator HOD

3. ACKNOWLEDGEMENT
I am very much indebted to Dr. Suma Bhat, Head of the Mechanical Engineering
Department, for her support and encouragement.
I also take this opportunity to express deep sense of gratitude to my seminar
coordinator, Mr. Pradeep Kamath, Assistant Professor, Department of Mechanical
Engineering, for his coordinal support, valuable information and guidance, which helped me
in completing this task through various stages.
I also wish to thank our Principal, Dr. Shreeprakash B, for his constant
encouragement without which this seminar would not have been possible.
I am also grateful to the faculty and staff members of the Mechanical Engineering
department, for their relentless support.
Last but not the least many thanks goes to the management who have given me the
opportunity to complete this seminar.

4. i
INDEX PAGE
Topic Page No.
ABSTRACT
1. INTRODUCTION 1
2. HISTORY 2
3. NEED FOR POWER STEERING 3
4. LAYOUT OF POWER STEERING 4
5. COMPONENT OF POWER STEERING 5-6
5.1 PUMP 5
5.2 STEERING GEAR 5
5.3 ROTARY VALVE 6
6. TYPE OF POWER STEERING 7-10
6.1 HYDRAULIC POWER STEERING 7
6.2 ELECTRIC POWER STEERING 8
6.3 ELECTRO HYDRAULIC POWER STEERING 10
7. BLEEDING OF POWER STEERING SYSTEM 11
8. TYPE OF POWER STEERING PUMP 12
9. TYPE OF POWER STEERING FLUID 13
10. PERFORMANCE PARAMETER 14
11. PROBLEM ASSOCIATED WITH POWER STEERING 15-16
12. ADVANTAGES OF POWER STEERING 17
13. CONCLUSION 18
REFERENCES 19

5. ii
FIGURE INDEX
Figure Page No.
Figure 4.1 Schematic layout of power steering 4
Figure 5.1 Pump of Hydro Electric Power Steering (HEPS) system 5
Figure 5.2 Representation of steering gear of an automobile 5
Figure 5.3 Rotary valve of a hydraulic power steering 6
Figure 6.1 Schematic representation of Hydraulic Power Steering (HPS) system 7
Figure 6.2 Representation of an Electric Power Steering (EPS) system 8
Figure 6.3 Electro Hydraulic Power Steering (HEPS) System 10

6. iii
ABSTRACT
The earth's fossil energy is not limitless, and we should be taking advantage of the
highly developed fields of science and technology to utilize it more efficiently and to create a
fully environmentally friendly life. Considering the prodigious amount of vehicles in the
world today, even a small improvement in their energy-saving performance could have a
significant impact. Hence to save fossil fuel & improve performance we came up with Power
steering Technology.
In automobiles, power steering (also known as power assisted steering (PAS) or
steering assist system) helps drivers steer by augmenting steering effort of the steering wheel.
Hydraulic or electric actuators add controlled energy to the steering mechanism, so the driver
needs to provide only modest effort regardless of conditions. Power steering helps
considerably when a vehicle is stopped or moving slowly. Also, power steering provides
some feedback of forces acting on the front wheels to give an ongoing sense of how the
wheels are interacting with the road this is typically called “road feel”.
In this paper we discus about Hydraulic Power Steering system, Electric Power Steering
system, Electro Hydraulic Power Steering system is described. Power steering has developed
around 1951 for the commercial use as we know today. Hydraulic Power Steering system is
not in much use today due to their low efficiency & high cost since they involve many of
mechanical parts. Now a day’s Electric & Electro Hydraulic Power Steering system are most
widely used because of two main advantages. First, it can significantly decrease the demand
on the motor so that it can be used for a wider range of vehicles. Second, its pressure-flow
characteristic can be programmed and is more flexible than hydraulic power steering (HPS)
system. A prototype with a 500 W motor was applied to a truck with a front load of 2,700 kg,
and static steer sweep tests were conducted to validate its feasibility.

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1. INTRODUCTION
In automobiles, power steering (also known as power assisted steering (PAS) or
steering assist system) helps drivers steer by augmenting steering effort of the steering wheel.
Hydraulic or electric actuators add controlled energy to the steering mechanism, so the driver
needs to provide only modest effort regardless of conditions. Power steering helps considerably
when a vehicle is stopped or moving slowly. Also, power steering provides some feedback of
forces acting on the front wheels to give an ongoing sense of how the wheels are interacting with
the road; this is typically called “rοad feel”.
Representative power steering systems for cars augment steering effort via an actuator, a
hydraulic cylinder, which is part of a servo system. These systems have a direct mechanical
connection between the steering wheel and the linkage that steers the wheels. This means that
power steering system failure (to augment effort) still permits the vehicle to be steered using
manual effort alone.
Other power steering systems (such as those in the largest off-road construction vehicles)
have no direct mechanical connection to the steering linkage; they require electrical power.
Systems of this kind, with no mechanical connection, are sometimes called "drive by wire" or
“steer by wire”, by analogy with aviation’s "fly-by-wire". In this context, “wire” refers to
electrical cables that carry power and data, not thin-wire-rope mechanical control cables.
In other power steering systems, electric motors provide the assistance instead of
hydraulic systems. As with hydraulic types, power to the actuator (motor, in this case) is
controlled by the rest of the power-steering system.
Some construction vehicles have a two-part frame with a rugged hinge in the middle; this
hinge allows the front and rear axles to become non-parallel to steer the vehicle. Opposing
hydraulic cylinders move the halves of the frame relative to each other to steer.

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2. HISTORY OF POWER STEERING
The first power steering system on an automobile was apparently installed in 1876 by a
man with the surname of Fitts, but little else is known about him. The next power steering
system was put on a Columbia 5-ton truck in 1903.
Robert E. Twyford, a resident of Pittsburgh, Pennsylvania, USA, included a mechanical
power steering mechanism as part of his patent (U.S. Patent 646,477) issued on April 3, 1900 for
the first four wheel drive system. Francis W. Davis, an engineer of the truck division of Pierce
Arrow began exploring how steering could be made easier, and in 1926 invented and
demonstrated the first practical power steering system. Davis moved to General Motors and
refined the hydraulic-assisted power steering system, but the automaker calculated it would be
too expensive to produce. Davis then signed up with Bendix, a parts manufacturer for
automakers. Military needs during World War II for easier steering on heavy vehicles boosted
the need for power assistance on armored cars and tank-recovery vehicles for the British and
American armies.
Chrysler Corporation introduced the first commercially available passenger car power
steering system on the 1951 Chrysler Imperial under the name “Hydraguide”. The Chrysler
system was based on some of Davis’s expired patents. General Motors introduced the 1952
Cadillac with a power steering system using the work Davis had done for the company almost
twenty years earlier. Charles F. Hammond, an American, born in Detroit, filed several patents for
improvements of power steering with the Canadian Intellectual Property Office in 1958.
Most new vehicles now have power steering, owing to the trends toward front wheel
drive, greater vehicle mass, and wider tires, which all increase the required steering effort.
Heavier vehicles, as are common in some countries, would be extremely difficult to maneuver at
low speeds, while vehicles of lighter weight may not need power assisted steering at all.

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3. NEED FOR POWER STEERING
a. To achieve highest possible road safety under increasing traffic density
b. To achieve highest possible road safety under high axel loads
c. To achieve greatest possible road safety under poor road condition
All of these conditions forces the driver operate vehicle at low speed, increasing the
fatigue of driver which affect judgment of driver. Poor judgment by the driver may lead to
accident. This led to development of power steering system.
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4. LAYOUT OF POWER STEERING
Figure 4.1 Schematic layout of power steering.
Oil Reservoir:
The greater the distance between the pump and reservoir, the more work the pump has to
do bringing the fluid in and the greater the effect of vehicle attitude on the system. Air in the
fluid can wreak havoc on a power steering system. Since the air can compress, whereas the
steering fluid does not, much of the force from the pump can be absorbed by the air instead of
being properly transferred to the steering box or cylinder. In addition, air can lead to pump
destruction. Air causes cavitations in the pump which will greatly increase wear and dramatically
shorten the life and performance of the pump.
Hydraulic Lines:
Flexible hoses due to the steering components movements
Filters:
a. Oil Filter
 Preferably installed in the return line.
 A 10-micron or smaller filter is recommended.
b. Air Breather Filter
 The “breather” or vent in the reservoir.
 A 3-micron filter is recommended.

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5. COMPONENT OF POWER STEERING
There are three main component of power steering system to control the steering system.
They are a. Pump, b. Steering gear and c. Rotary valve.
5.1 PUMP
Figure 5.1 Pump of Hydro Electric Power Steering (HEPS) system.
The fluid pump is a vane type driven by the engine via belt. The reservoir tank is
mounted on the vehicle body. The fluid pump incorporates the flow control valve and relief
valve, each performing the following functions: The flow control valve regulates the flow rate of
discharged fluid to a constant level irrespective of the engine speed. The relief valve protects the
system from an excessively high pressure which may occur, for example, when the steering
wheel is turned all the way.
5.2 STEERING GEAR
Figure 5.2 Representation of steering gear of an automobile.

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Figure shows the typical representation of rack & pinion gear. It is basically just the rack
sliding over the pinion for the control of the flow rate. It is the very important part of the whole
power steering system. There should be a smooth flow of the fluid in order to get the smooth
control of the steering.
5.3 ROTARY VALVE
Figure 5.3 Rotary valve of a hydraulic power steering.
Rotary valves are present inside the steering gear system. They control the flow of fluid
or oil in the steering gear system.

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6. TYPE OF POWER STEERING
There are three main types of power steering system. They are Hydraulic power steering
system, Electric power steering system, Hydro electric power steering system.
6.1 HYDRAULIC POWER STEERING (HPS) SYSTEM
Figure 6.1 Schematic representation of Hydraulic Power Steering (HPS) system.
Most power steering systems work by using a hydraulic system to steer the vehicle’s
wheels. The hydraulic pressure typically comes from a gerotor or rotary vane pump driven by the
vehicle’s engine. A double-acting hydraulic cylinder applies a force to the steering gear, which in
turn steers the road wheels. The steering wheel operates valves to control flow to the cylinder.
The more torque the driver applies to the steering wheel and column, the more fluid the valves
allow through to the cylinder, and so the more force is applied to steer the wheels.
One design for measuring the torque applied to the steering wheel has a torque sensor – a
torsion bar at the lower end of the steering column. As the steering wheel rotates, so does the
steering column, as well as the upper end of the torsion bar. Since the torsion bar is relatively
thin and flexible, and the bottom end usually resists being rotated, the bar will twist by an
amount proportional to the applied torque. The difference in position between the opposite ends
of the torsion bar controls a valve. The valve allows fluid to flow to the cylinder which provides
steering assistance; the greater the “twist” of the torsion bar, the greater the force.

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Since the hydraulic pumps are positive-displacement type, the flow rate they deliver is
directly proportional to the speed of the engine. This means that at high engine speeds the
steering would naturally operate faster than at low engine speeds. Because this would be
undesirable, a restricting orifice and flow-control valve direct some of the pump’s output back to
the hydraulic reservoir at high engine speeds. A pressure relief valve prevents a dangerous build-
up of pressure when the hydraulic cylinders piston reaches the end of its stroke.
Some modern systems also include an electronic control valve to reduce the hydraulic
supply pressure as the vehicle’s speed increases; this is variable-assist power steering. The
steering booster is arranged so that should the booster fail, the steering will continue to work
(although the wheel will feel heavier). Loss of power steering can significantly affect the
handling of a vehicle. Each vehicle owner’s manual gives instructions for inspection of fluid
levels and regular maintenance of the power steering system. The working liquid, also called
"hydraulic fluid" or “oil”, is the medium by which pressure is transmitted. Common working
liquids are based on mineral oil.
6.2 ELECTRIC POWER STEERING (EPS) SYSTEM
Figure 6.2 Representation of an Electric Power Steering (EPS) system.

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Electric power assisted steering (EPS/EPAS) or motor driven power steering (MDPS) uses
an electric motor to assist the driver of a vehicle. Sensors detect the position and torque of the
steering column, and a computer module applies assistive torque via the motor, which connects
to either the steering gear or steering column. This allows varying amounts of assistance to be
applied depending on driving conditions. Engineers can therefore tailor steering-gear response to
variable-rate and variable damping suspension systems, optimizing ride, handling, and steering
for each vehicle. On Fiat group cars the amount of assistance can be regulated using a button
named “CITY” that switches between two different assist curves, while most other EPS systems
have variable assist. These give more assistance as the vehicle slows down, and less at faster
speeds.
A mechanical linkage between the steering wheel and the steering gear is retained in EPAS.
In the event of component failure or power failure that causes a failure to provide assistance, the
mechanical linkage serves as a backup. When EPAS fails, the driver encounters a situation where
heavy effort is required to steer. This heavy effort is similar to that of an inoperative hydraulic
steering assist system. Depending on the driving situation, driving skill and strength of the
driver, steering assist loss may or may not lead to a crash. The difficulty of steering with
inoperative power steering is compounded by the choice of steering ratios in assisted steering
gears vs. fully manual. NHTSA has assisted car manufacturers, such as Ford, with recalling
EPAS systems prone to failure.
Electric systems have an advantage in fuel efficiency because there is no belt-driven
hydraulic pump constantly running, whether assistance is required or not, and this is a major
reason for their introduction. Another major advantage is the elimination of a belt-driven engine
accessory, and several high-pressure hydraulic hoses between the hydraulic pump, mounted on
the engine, and the steering gear, mounted on the chassis. This greatly simplifies manufacturing
and maintenance. By incorporating electronic stability control electric power steering systems
can instantly vary torque assist levels to aid the driver in corrective maneuvers.
The first electric power steering system appeared on the Suzuki Cervo in 1988. Today a
number of manufacturers use electric power steering.

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6.3 ELECTRO HYDRAULIC POWER STEERING (EHPS)
SYSTEM
Figure 6.3 Electro Hydraulic Power Steering (HEPS) System.
Electro hydraulic power steering systems, sometimes abbreviated EHPS, and also
sometimes called “hybrid” systems, use the same hydraulic assist technology as standard
systems, but the hydraulic pressure comes from a pump driven by an electric motor instead of a
drive belt at the engine.
In 1965, Ford experimented with a fleet of “wrist-twist instant steering” equipped
Mercury Park Lanes that replaced the conventional large steering wheel with two 5- inch
(127mm) rings, a fast 15:1 gear ratio, and an electric hydraulic pump in case the engine stalled.
In 1988, the Subaru XT6 was fitted with a unique Cybrid adaptive electro-hydraulic steering
system that changed the level of assistance based on the vehicle’s speed.
In 1990, Toyota introduced its second-generation MR2 with electro-hydraulic power
steering. This avoided running hydraulic lines from the engine (which was behind the driver in
the MR2) up to the steering rack.
In 1994 Volkswagen produced the Mark 3 Golf Ecomatic, with an electric pump. This
meant that the power steering would still operate while the engine was stopped by the computer
to save fuel. Electro-hydraulic systems can be found in some cars by Ford, Volkswagen, Audi,
Peugeot, Citroen, SEAT, Skoda, Suzuki, Opel, MINI, Toyota, Honda, and Mazda.

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7. BLEEDING OF POWER STEERING SYSTEM
When bleeding air from a power steering system, please follow AGR’s bleeding
Instructions only. AGR has found the following method is the only proper way to bleed a system.
Do not start the engine until system is fully bled. If on a Hydro Boost system, follow hydro boost
bleeding procedures after bleeding the power steering system.
When to Bleed
• After any steering component replacement.
• If any part of the power steering system is opened for any reason.
Why to Bleed
• To prevent pump damage.
• To ensure proper system operation.
• To stop steering system noise.

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8. TYPE OF POWER STEERING PUMP
The following are some of the pumps used in power steering system.
a. Vane Power Steering Pump:
Vane pumps are the most common type of power steering pump used. In this type of pump
the rotor is housed in an oval- or elliptical-shaped housing where it turns. Vanes fitted to the
outside diameter of the rotor sit against the housing walls as the rotor turns. When power steering
fluid enters into the vane pump housing it is trapped between the vanes, the housing wall and the
rotor. A subsequent pressure increase causes the fluid to be pumped out of the housing and then
through the outlet chambers.
b. Roller Power Steering Pump:
In a roller power steering pump, wide V-shaped grooves cut into the side of the rotor allow
steel rollers to ride along the inside contour of the pump. The pump is contained in an oval-
shaped housing within the pump body. Centrifugal force pushes the rollers to the oval's outer
edge where they trap fluid, similar to the way the vanes catch the fluid in a vane pump. The
pressurized fluid is forced out through two outlets in the pump, driving the power steering
system.
c. Slipper Power Steering Pump:
Just like the vane and roller pump, the slipper power steering pump has a rotor housed in an
elliptical-shaped chamber that rotates within the body of the pump. Fitted into wide slots on the
rotor are springs that are topped with scrubber-type "slippers." The springs keep the slippers in
constant contact with the wall of the pump. As fluid enters into the pump, pressure is built up and
released to drive the power steering system.

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9. TYPE OF POWER STEERING FLUID
The following are some of the type of steering fluid used.
a. Dedicated Steering Fluids:
The chemical composition of dedicated power steering fluids varies by maker, but all will
be marked as "Power Steering Fluids" and usually be composed of mineral oil, polyalphaolefin
or organophosphate ester. They may also have glycols, silicon’s and corrosion inhibitors added.
b. Transmission Fluids:
Not all cars use dedicated power-steering fluid. Some systems use transmission fluid for
hydraulic pressure in the steering system. The car's manual should specify which type of
transmission fluid should be used in the power steering system.
c. Manufacturer's Steering Fluids:
Many manufacturers, including GM and Honda, make their own steering fluids. Although
any kind of power steering fluid will usually work, performance is often optimized by using the
manufacturer's label, which can be bought from any parts supplier for that make of car.
d. Interchangeable Steering Fluids:
There are many brands of power steering fluid designed for use in all steering systems.
Though they are not distinguished by type, their chemical compositions are different from
manufacturer to manufacturer.

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10. PERFORMANCE PARAMETER OF POWER
STEERING
There are two main performance parameter used to measure the performance of the
power steering system. They are a. accuracy b. reliability.
a. Accuracy:
Power steering system is highly accurate when compare to the normal steering mechanism.
In normal steering mechanism steering will become hard because of the friction involved in the
mechanical parts but in power steering mechanism most of the friction is reduced due to the fluid
mechanics. Fluid mechanics makes the steering effortless since no friction is involved.
b. Reliability:
Power steering system is most reliable than the other steering mechanism. Breakdown of
the power steering system doesn’t occur frequently. It has very smooth handling compare to
other steering mechanisms.

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11. PROBLEM ASSOCIATED WITH POWER
STEERING
There are 6 commonly encountered problems in power steering system. They are,
a. Power Steering Leak:
The most common power steering problem that people are going to find is a leak in the
system. This problem has a few different signs that will help you diagnose is pretty quickly.
Besides the tell-tale sign of fluid on the driver’s side of the vehicle, you will also notice a
grinding noise when you turn the wheel. When you hear the grinding noise you are getting to the
point where the fluid is very low and it must be fixed quickly. If you run out of fluid, the pump
can burn out completely.
b. Drive Belt Slipping:
Another very common problem that is associated with the power steering is when the belt
in the pump will start to slip. You will notice this very quickly when you hear a very loud
squealing sound when you turn the steering wheel in a sharp turn. For example, when you come
to a stop and must turn onto a new street, you will hear a squealing sound as you turn the wheel
all the way in which ever direction you go.
c. Cracked Hoses:
After several years of use, you will find that some of the hoses that are associated with the
power steering can start to become dry and cracked. The only way to realize this before you start
to have a leak is with a periodic inspection of the hoses and other components in your car's
engine compartment.

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d. Hose is worn:
Because of the close proximity to other parts in the engine bay, there is the chance that
there will be contact with other parts as the vehicle is driven. This contact can begin to wear a
hole in the side of a hose, or start to make the hose a little spongy on one side. After some time
the pressure in the hose can cause it to burst while driving. A sudden loss of pressure from the
hose will cause your steering to get very hard quickly.
e. Peeling Hose:
Another problem associated with the power steering is found after it has been worked on.
When the hose has been over crimped at one end, you will notice a little bit of peeling back on
the hose. When you take your care in to be serviced you should continue to check for leaks and
any those problems like the hose peeling so you can take it back in.
f. Coupling Creeps Off:
If you have owned your vehicle for several years, and drive it a lot, one more problem that
you can find is that the coupling on the hose will begin to creep off. With a visual inspection of
the power steering you will see this happening.

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12. ADVANTAGES OF POWER STEERING
 Effortless steering.
 Precise & quick response.
 Absorbs road shocks.
 Greater safety and controllability under critical situations.

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13. CONCLUSION
By studying all these we can conclude that the power steering is necessary for the modern
cars. Now a day we can see almost all cars having a power steering. It provides good handling to
the driver, gives better comfort and make him less fatigue.

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REFERENCES
[1] Shin-Hung Chang et al, “Implementation and Control Logic Design of Intelligent Electric
Power Steering System”, World Electric Vehicle Journal, EVS24 International Battery, Hybrid and
Fuel Cell Electric Vehicle Symposium, 2009, PP 195.
[2] Simonp et al, “PowerSteering”, http://en.wikipedia.org/wiki/Power%20steering?Oldid=662
090545.
[3] Schultz, Mort (May 1985). “Steering: A Century of Progress”. Popular Mechanics 162 (5):
59. ISSN 0032- 4558. Retrieved 8 November 2014.
[4] Driving-Gear For Motor Carriages”. United States Patent and Trademark Office. Nunney,
Malcolm James (2006).
[5] Light and Heavy Vehicle Technology. Elsevier Science. p. 521. ISBN 978 0-7506-8037-0.
Retrieved 18 June 2010.