International Journal of Scientific and Research Publications, Volume 2, Issue 4, April 2012
ISSN 2250-3153
1
AN ERGONOMIC DESIGN OF PEDAL OPERATED
FLOUR MILL
Mr. Prasad A Hatwalne, Mr. Mahesh Gorde, Mr. Swapnil B. Patond, Mr. Parvezalam I. Shaikh
Abstract- The socio economic conditions of peoples living in
village sides of developing countries like India, ever increasing
energy crises, and the increasing awareness to ourselves
physically fit are the driving forces for the development of pedal
operated mechanisms for performing many day to day activities.
Such human energized mechanisms are used to generate power,
to operate flour mill etc. But one common oblivious question that
stuck in everyone’s mind is about the level of comfort that it
provide during its operation.
Wheat and wheat flour forms the staple food of majority of
population in India. Hence to encompass all these needs and
facts, in this paper an attempt is made to develop an pedal
operated flour mill with giving due respect to human capabilities.
To make this design of pedal operated flour mill is ergonomically
viable the structure (geometry) of the flour mill is made by
taking into consideration the anthropometric data so as to provide
comfortable posture during its operation.
Index Terms- pedal operated flour mill, ergonomics,
anthropometric.
I. INTRODUCTION
W
heat and wheat flours are the integral of daily diet of
Indian population. The wheat kernels are processed in
chakki (flour mill) to produce wheat flour is which is then used
to make breads, biscuits, pastas etc. In India chapatti and other
variants of wheat forms the staple food of majority of population.
In manual process the flour is produced by hand cranking the
conventional stone wheels. But this method is characterized by
slow operation, low production rate. Further this hand cranking
process is physically demanding through energy and postural
requirements. It may also leads to clinical and anatomical
disorders which may affect operator’s health.
In order to make it possible to operate the system effectively
and efficiently it is necessary to develop this system by giving
due respect to human limitation. Hence ergonomic system of
pedal operated flour mill is developed. The ergonomic
consideration mainly includes the selection of components of
system which suits the human capability and develops the
posture to operate system to reduce the fatigue and chances of
musceletole disorders.
II. PEDAL OPERATED FLOUR MILLCONSTRUCTION AND WORKING
In construction the pedal operated flour mill basically consists
of two units namely the drive unit and processing unit. The drive
unit mainly concerns with transmission of human power to
processing unit. This transmission of human power to processing
unit is accomplished in two stages. In first stage the operator uses
his feet and legs to rotate pedal around the crank axel. The pedals
in turn are fixed to chain ring (sprocket) with the teeth’s that
engages continuous chain. The chain then transmits the pedaling
action to cog on the front wheel causing the front sprocket to
rotate and then drive shaft on which pulley is mounted. In second
stage this power from shaft and pulley is transmitted to
processing unit through belt drive.
The processing unit essentially consists of stone wheels,
hopper, and hemispherical collector. The stone wheels are
operated by power from the belt drive where the wheat kernels
which are fed into hopper are crushed and powered wheat flour is
collected in hemispherical collector.
III. ERGONOMICS DESIGN OF PEDAL OPERATED
FLOUR MILL
Making this design ergonomically viable mainly concerns with
developing the posture to provide best possible comfortable
posture to operator during its working so as to get maximum
throughput. This can be achieved by selecting and arranging the
components of system that best suits to human capabilities.
Since the thigh or quadriceps is largest and most powerful
muscles in human body with the body in seat and legs can
produce pedal work [1]. The person can generate four times more
power (1/4 horsepower (hp)) by pedaling than by hand cranking.
At the rate of 1/4 hp, continuous pedaling can be done for only
short time, about 10 minutes. However pedaling at half of this
power (1/8 hp)can be sustained for around 60 minutes Maximum
power produced with legs is generally limited by adoptions
within the oxygen transportation system. On the other hand the
capacity for arm exercise is dependent upon the amounts of
muscle mass engaged and that is why a person can generate more
power by pedaling than hand cranking [2]. Pedal power enables a
person to drive device at same rate as achieved by hand. Thus it
makes sense to utilize this human muscle for generating as much
as energy from human body.
In order to provide the ergonomically comfortable system it is
necessary to locate the various elements of system so that a
person can operate the system with less effort and hence the
fatigue. As the thigh is being utilized to generate the power
continuously it was decided to develop a posture which is similar
to cycling posture. And subsequently the ergonomic design
mainly concerned with the saddle (seat) position, handle position.
Saddle position includes the height of saddle, distance between
saddle and pedal crank center, seat tube angle. Whereas handle
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International Journal of Scientific and Research Publications, Volume 2, Issue 4, April 2012
ISSN 2250-3153
position includes handle height, handle width, distance between
saddle and handle.
2
Thus by using cosine rule we can obtained the distance
between shoulder and wrist with elbow angle 150°
IV. SADDLE DESIGN
A. Saddle height from pedal crank center
It is biomechanically logical that in order to have comfortable
posture there should be an optimal saddle height [3]. This saddle
height is obtained by keeping in mind certain facts.
The normal pedaling rate for average healthy person is around
70-80 rpm because of optimum oxygen intake [6]. Patellar
tendontisis is common injury resulting because of low saddle
height. The low saddle height cause the over compression of
knee, resulting in anterior knee pain [5]. On the other hand the
Biceps tendontisis is injury caused because of saddle height that
is too high which causes the over stretching at the bottom of
stroke. Hence in order to achieve this balance it recommended
that saddle height should be such that knee angle at the bottom of
stroke should between 25-35° [5].
This saddle to pedal height is achieved by Greg-lemond
method. According to lemond method the distance between
saddle and pedal should be 88.3% of inseam length [5]. Now on
the basis of anthropometric data for Indian context the average
inseam length of an Indian is 76.35cm [5]. And hence the saddle
to handle distance according to lemond method will be
Saddle height = 0.883*inseam length
= 0.883*76.35
Saddle height = 67.42 cm
B. Seat tube angle (STA)
For comfortable posture the optimum seat tube angle should be
82°. This angle causes the operator to move forward relative to
crank axis. As a result of this forward movement. The hip is
more extended during the power phase of pedaling [6]. Brown et
al (1996) has observed that this extended movement causes the
operator to generate greater hip torque thus enables operator to
generate more power. Hence the seat tube angle taken is 82°.
V. HANDLE DESIGN
A. Saddle to handle distance
For handle designs following points regarding human comfort
were taken into consideration.
1) For easy and comfortable riding wrist angle should not
be straight. It should be between 170°-190° [7].
2) The elbow angle should be between 150°-165° [7].
3) The angle between upper arm and trunk should be
around 20° to reduce the effect of possible vibration to
shoulders [8].
4) Further the posture should be such that operator should
lean forward approximately 15° w.r.t vertical axis which
increases the respiratory volume because it transfers
part of shoulders weight to arms and reduces the load to
lower back area without overloading the arms and
wrist[8].
From the anthropometric data, we have
Upper arm length = 21 Cm [7].
Lower arm length =24.2 Cm [7].
Hand length = 18.7 Cm [7].
Cos A = (b²+C²-a²)/2bc
Cos 150° = (21.2²+24.22²-a²)/2*21*24.2
Therefore a = 43.8cm.
That is saddle to handle distance = 45cm
As the shoulder angle should be around 20° to reduce the fatigue
as stated earlier.
The handle height needs to be calculated. This can be found out
by graphical method.
Figure: 1
Thus we have following dimensions.
Saddle to handle distance = 45cm
Handle width = 58cm i.e. equal to shoulder width
Handle grip length = 15cm.
Geometry of the structure according to dimensions we obtained
is as follows.
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International Journal of Scientific and Research Publications, Volume 2, Issue 4, April 2012
ISSN 2250-3153
VI. RESULT
3
proposed a simplistic design that can deliver efficient, productive
and reliable flour mill which can be used in rural as well as urban
areas. this equipment can be easily operated by semi rather low
skilled operator. Further this equipment can easily find its place
where there is no or limited power supply.
REFERENCES
[1]
[2]
[3]
The pedal operated flour mill is fabricated according to the
dimensions which were derived suitable to human anthropometry
so as to reduce the possible fatigue during its operation. After
fabrication several trials were conducted on it and their
corresponding time of pedaling and output rate of flour were
taken down for different pedaling rate.
For conducting trials 8 personals from age group 20-35 were
selected. The mean (± SD) of age, weight, height were 26.5±
3.5.years, 68.62±21 Kg, 176.8±3 cm respectively. All the trials
started at 10 A.M.in the morning in the laboratory where the
room temperature varied from 25-28˚C and relative humidity was
50-60% during experiment. In order to find out most efficient,
productive way operating the system, the input pedaling rate is
set in three stages vise 30-50-rpm, 50-70 rpm, and 70-90 rpm.
For 30-50 rpm, production rate observed was slow but the
texture of flour was fine enough. The production rate found to be
25 mins per Kg& average time that subject can maintain the
pedaling is 15 mins .For 70-80 rpm the production rate of flour
was observed to be maximum but the flour obtained was
somewhat coarser and requires regrinding. Further it was finding
difficult to maintain this pedaling rate more than 5 mins. When
input pedaling rate is set to 50-70 rpm 1 Kg of wheat requires 15
mins. To get required fineness double crushing was required but
not to extent as that requiring at higher pedaling rate. So overall
for 1Kg requires 20 mins and this pedaling rate found more
comfortable than other two.
VII. CONCLUSION
The main objective behind development of pedal operated
flour mill was on producing cheap, easy to operate system which
can be easily fabricated by readily available material and thus we
[4]
[5]
[6]
[7]
[8]
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AUTHORS
First Author – Mr. Prasad A Hatwalne1,
M.E.(CAD/CAM), PRMIT&R, Badnera, (M.S.), India
E-mail id : hatwalneprasad1@gmail.com
Scholor
Second Author – Mr. Mahesh Gorde, Scholar M-tech (Industrial
Engg), RKNCE, Nagpur, (M.S.), India
E-mail id - gordemahesh7@gmail.com
Third Author – Mr. Swapnil B. Patond, Scholar B.E. (3rd year/
Mech.), JDIET, Yavatmal, (M.S.), India
E-mail id - swaps.patond@gmail.com
Fourth Author – Mr. Parvezalam I. Shaikh, Scholar B.E. (3rd
year/ Mech.), JDIET, Yavatmal, (M.S.), India
E-mail id - parvyashaikh02@gmail.com
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