retractable steering

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ISSN : 23193182, Volume-2, Issue-1, 2013

124

Retractable Impact Absorbing Steering

Mubeen. N, Deepan Raj. C & Praveen Kumar. S

E-mail : [email protected],[email protected],[email protected]

Abstract - In the present scenario transportation has

become an important parameter thus it requires the

implementation of safety factors in the automobile at low

cost which can be afforded even by a common man . Our

project deals with the idea of implementing retractablesteering in the car which helps to absorb the impact

experienced by the driver during the time of collision at

low cost.

I. INTRODUCTION

The retractable energy absorbing steering column

provides safety to the driver driving the all-terrain

vehicle. This system helps to reduce the impact load

acted on the driver when the vehicle meets an accident

in the front side. The spring in the system will absorb

the load acting on it during the collision thus preventing

the driver from direct collision with the steering wheel.

This setup is placed at the steering column and thelocking mechanism provided will lock the steering

wheel when the spring completely absorbs the load.

The system is said to be retractable since after the

collision or accident the same steering system can be

used instead of replacing it. But this is not possible in

case of air bag system and collapsible steering system,

where once they are used they cannot be reused. Their

cost is also high when compared to this system what wehave designed. Hence by using this mechanism we can

able to reduce the injuries caused to the driver during

the accident with the help of less cost and it can also be

reused for an all-terrain vehicle.II. OBJECTIVE

The main objective of the project is to design the

steering mechanism which absorbs the load acted on the

steering wheel when the driver collides with it during

the accident. It also should be capable of locking thesteering wheel once it absorbed the load and should be

able to retract it whenever it is needed.

Thus the steering should able to withstand

maximum impact given by the driver but it should not

be designed such that it remains rigid when the driver

collides with the steering wheel. Whenever the impact isapplied to certain limit then the system should function

effectively by absorbing the maximum load and it

should be locked such that it never reciprocates back asit will lead to great damage to the driver. This is the

main parameter to be considered in designing the system

and fabricating it. The dimensions are chosen in such a

way that the work pieces required to machine and

assemble are easily available in around and hence its

become handy to get a new one in case if any

mistakes/errors occur during the course of our project

work.

III. CONCEPTUAL DESIGN

Figure 1 : Conceptual Design


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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)


125

The steering system provides the directional

stability to the vehicle. Along with these operations it

also performs the safety operation by absorbing the

impact load given by the driver to the steering wheel

and locks it there by providing safety to the driver. Then

the locking mechanism is used to retract the steeringsystem and it can be used further.

For designing this steering system the components

required are compression spring, hollow pipe of internal

diameter equal to the outer coil diameter of the

compression spring, the locking mechanism usually of

ratchet and pawl which provides the locking in one

direction. The designing of system is simple but it is

essential to determine the exact specification of the

spring since it plays a major role in the system. And the

location of spring should also be considered so that there

is sufficient space for the steering column to get into the

compression of the spring. Then the vital factor is thefree length of the spring which determines the maximum

load which can be absorbed by it when the driver

collides with the wheel. The locking setup is placed atthe junction of hollow pipe and the steering column such

that the releasing knob is facing outwards.

The location of the steering column along with the

steering wheel that is the angle at which it should be

placed so that it absorbs the maximum load acting on itand at which distance from the driver the steering wheel

should be placed. This is determined by using certain

calculation and placed according to it.

The design is such a way that the spring is placedinside the hollow pipe which has the base covered by

the plate so that the spring rests on it. The plate throughwhich steering column is passed is placed over the upper

side of the spring so that when the load is given to the

steering wheel it transfers the load completely to the

spring. Then the locking mechanism is placed where the

steering column is locked and the releasing pin facing

outward.

Taking all these factors into the consideration, a

design of steering mechanism is made which has the

ability to absorb the load and lock it and release it

whenever it is needed.

IV. DETAILED DESIGN

4.1 Modeling

Modeling is performed using SOLIDWORKS 2011

software.

Design has been made with the followingconsiderations as listed:

Identification of dimensions of compression

spring and locking mechanism.

Identification of suitable dimension for

hollow pipe and suitable base plates.

Base plate is fixed to the base of the hollow

pipe.

Provision for placing the spring inside thepipe.

Identification of gap between the pipe and

the spring.

Provision for covering the upper side of thespring using plate along with steering

column.

Provision for placing the locking mechanism.

Provision for adjustment of clearance

between the column and the plate.

4.2Design Calculations

Calculation of load

Car speed = 30 km/hr = 8.33 m/s

Assuming stretching distance of a seat belt =1.5 ft

Mass of the driver = 70 kg

1. v2=u

2-2as

a= (v2u

2)/2*s

a= (8.3320

2)/2*0.46

a=75.88m/s2

1. Force on driver, F=m*a

F = 70*75.88

F =5311.8548 N

Calculation of springType =

squared and grounded

Active no. of coils

(n) = 10

Total no. of coils (Nt) = 12

Coil diameter (d) = 8 mm

Mean diameter of spring (D) = 55 mm

Free length of spring (Lf) = 300 mm

Spring index, c = D/d

c = 55/8

c = 6.875


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1. Pitch of the coil, p = free length/ (N t1)

2. P = 300/ (121)

3. P= 27.27 mm

4. Solid length, Ls= Nt*d

Ls= 12*8

Ls= 96 mm

5. Maximum deflection, Ymax= Lf -LYmax = 30096

Ymax= 204 mm

6. Maximum load, Pmax= G*D4*Ymax/8*D

3*n

Pmax = 204*.79*105*8

4/8*55

3*10

Pmax= 4959.5 N

7. Spring rate (or) stiffness, q = G*d/8*c3*n

q =0.79*105*8/8*(6.875

3)*10

q = 24.11 N/mm

4.3 Design Specifications

Spring

Free length = 300 mm

Total no. of coils = 12

Coil diameter = 8 mm

Effective spring diameter = 55 mm

Pitch of spring = 27.27 mm

Stiffness = 24.11 N/mm

Maximum defection = 204 mm

Maximum energy absorbed = 4959.5 N

Hollow pipe

Length of the pipe = 350 mm

Diameter of pipe = 65 mm

4.4 Design Of Spring

A spring is defined as an elastic machine

element, which deflects under the action of the load

and returns to its original shape when the load is

removed. The type of spring we used is the squared

and grounded type compression spring and the total

number of active coils is 10 and the number of

inactive coils is 2 and hence total number of coils is

12. The mean diameter of the spring is 55mm of

which coil diameter is 8mm. the stiffness of the

spring is 24.11N/mm and the total length of the

spring is 300mm having pitch of 27. The solid

length of the spring is 96mm and the maximum

load which the spring can withstand is 4959.5N.The design is performed in Solidworks and is

drafted to obtain a 2D sketch of the same.

Figure2 SPRING

4.5 Retractable Energy Absorbing Steering Column 3d

Assembly Model

V. WORKING PRINCIPLE

The spring is placed inside the hollow pipe so that

the base of the spring rests on the base plate in the pipe.

The upper side of the spring is covered with the help of

the plate which is connected with the steering column sothat the twisting force given to the steering wheel

directly passes to the steering column and so that spring

does not produce any effect on it. The locking

mechanism is provided at the joining of the steering

column along with the hollow pipe.

When the driver meets an accident the impact load

produced by the driver is acted on the steering wheel

which is carried on to the spring which is placed on its

way. Thus the spring will absorb the entire load acted on

it. Then the steering column moves inside the spring so

that the spring gets compressed till its free length andgets locked at some point so that it does not retract back.

Thus providing the safety to the driver by preventing

him from the sudden impact created due to the accident.

When it is needed the locked steering column can

be retracted back so that it can be used for the further


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purpose. This is the main advantage of the system since

in other safety system it is not possible to use it as once

used they cannot be used further.

This mechanism can be connected to the steering

system of an all-terrain vehicle where the safety plays animportant role.

VI. FABRICATION OF CONSTRUCTION

The safety system is manufactured by making a

spring of about 300mm in length of mean coil diameter

of about 55mm which has the coil diameter of 8mm.

Then the hollow pipe of length 350mm is cut and it is

68mm in diameter. The base plates are fabricated of thesame size meeting the pipe dimension so that it covers it

completely. Then in the steering column using shaping

machine the grooves are taken such that it provides the

locking mechanism in one direction. These components

are then welded accordingly that the operations of all the

components are not affected.

Operations Used

1. Metal cutting

2. Grinding

3. Filing

4. Shaping

5. Welding

STEPS OF THE PROJECT FABRICAITON

STEP-1

The spring is designed according to the required

dimensions

STEP-2

The hollow pipe and the base plates are machined

in such a way that it completely covers the pipe.

STEP-3

The grooves are taken in the steering column rod to

provide the locking mechanism in one direction.

STEP-4

The base plate is first fixed at the base of the pipe

so that the steering column rod passes through it.

STEP-5

Then the spring is placed over it and at the top of

the spring another base plate covers it which helps totransfer the load to the spring. The joining is done using

welding.

STEP-6

The steering column rod passes through the base

plates and it has the groove at the outside of the plateand hence the locking can be done in outward

directions. Then the spring is setup for the lockingmechanism.

Fabricated steering column

Figure 4 STEERING COLUMN

VII. MACHINE TOOL USED

7.1 LATHE

The main function of the lathe is to remove metal

from a piece of work to give it the required shape and

size. This is accomplished by holding the work securely

and rigidly on the machine and then turning it against

cutting tool which will remove metal from the work in

the form of chips. To cut the material properly the toolshould be harder than the material properly the tool

should be harder than the material of the work piece,

should be rigidly held on the machine and should be fed

or progressed in a definitely way relative to work.

7.2 SHAPING MACHINE

The shaper is a reciprocating type of machine tool

intends primarily to produce flat surface. The surfaces

may be horizontal, vertical or inclined. The shaper

machine can produce any surface composed of straight

line elements and contoured surface. We used universal

shaper machine to produce groove the steering column.The cutting tool used is a square nose tool to produce

groove in the steering column. The column is clamped

on the table. The length and the position of stroke is

carefully adjusted.

7.3 ARC WELDING MACHINE

Welding is process of joining similar metals byapplication of heat with (or) without application of

pressure and addition of filter material. We used arc

welding for joining spring with the mild steel material.

Both direct current and alternating current are used for


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electric arc welding. Both the consumable and non-

consumable electrodes are used for this welding. But in

this case we used consumable electrode. In this method

the tungsten rod is used as negative electrode and the

work being welded as positive. The arc produced

between these two electrodes heats the metal to themelting temperature.

VIII. SKILL SET LEARNT

LATHE

By using the lathe machine we learnt to

machine the work piece in terms of turning, facing

operations. The holding of work piece in the machineand fixing the tool and provide feed accordingly to

machine the work piece. Handling of machine and work

pieces and performing the various operations in the

machine has been learned.

IX. ARC WELDING

The welding of different materials using the

electrode is learnt. Providing the suitable current supply

and welding accordingly. Then we have learnt what are

the safety measures needed before and while doing theprocess. How to fix the electrodes and how to remove

those are learnt in an effective way while doing our

project.

X. SHAPING MACHINE

Shaper machine is used to cut the groove on the

steering shaft. The knowledge about how to adjustlength of stroke, type of tool to be used and how to give

feed to cut the groove is learnt.

XI. CONCLUSION

Retractable energy absorbing steering column

can be effectively used in all-terrain vehicle to provide

safety to the driver. This system is cheaper than the

other safety items like air bag and collapsible steeringcolumn and the important thing is its retractable needs

no replacement. It absorbs nearly about 5KN of the loadgiven to the driver and thereby providing safety to the

driver. Only if the load exeeds the maximum absorbtion

capacity of spring the load would be directly acthing on

the driver. However the damage to the driver is reduced.

Hence it can be used in an ATV to improve the safety of

the driver.

XII. REFERENCES

[1] Bhandari,V. B. (2010) Design of Machine

Elements,McGrawHill, third edition, pp.383-

435.

[2] Kirpal Singh (2011) Automobile Engineering-volume1,standard publishers, pp.236-240.

[3] PSG design data(2011), kalaikathir achchagam.

[4] www.physicsforum.net

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