Jato is a traditional type of rotary hand mill or grinder within the Himalayan region of Nepal, Sikkim,Darjeeling and Bhutan used to grind grains. It consists of two round stones disc of which upper part is movable and lower disc are immovable and includes a huge nail or wood (mani) within the center The top half has two holes in it, one within the middle to insert grains or for feeding purpose and the other on the side to place a wooden handle (hato) for grinding. The grains are grind using a circular motion with the help of the handle and the person has to be sit right down to do the task.

1. Department of Mechanical
Engineering
Kathmandu University
Machine Element Design and Process II
(MEEG 318)
CASE STUDY ON JAATO
Submitted by:
Abhishek Neupane
ME II (Energy Technology)
Exam Roll No.: 016139
3rd Year/2nd Semester
Submitted to:
Dr. Ranjit Shrestha
Department of Mechanical
Engineering
Date of Submission: 27th July, 2020

2. INTRODUCTION AND BACKGROUND
Jato is a traditional type of rotary hand
mill or grinder within the Himalayan region
of Nepal, Sikkim,Darjeeling and Bhutan
used to grind grains. It consists of two
round stones disc of which upper part is
movable and lower disc are immovable
and includes a huge nail or wood (mani)
within the center.
The top half has two holes in it, one within the middle to insert grains or for feeding
purpose and the other on the side to place a wooden handle (hato) for grinding. The
grains are grind using a circular motion with the help of the handle and the person
has to be sit right down to do the task.
Fig 1. Traditional Jato

3. Advantages
• Reduce act of force
• No maintenance required
• One time investment
• Efficient flow of grinned grain
Disadvantages
• Difficult to carry from one place to
other due to its bulky size
• Not suitable for children
• There is pain on palm when it is run for
long time

4. EVOLUTION
Changes occurs during time interval
It is believe that Jato (Grinder) was invented centuries ago. In ancient time people use
different simple machine to do their daily works. Some of the simple machine and
from these machine evolution of such machines drastically changed. The purpose is
same but the ways are different. A lots of study was done to reduce effort because of
this we can got compact size appliances in our home.
It is simply operated when one person stands on the
long thick plank of wood making effort at every interval),
a long and thick plank of horizontal wood which has a
small vertical extension that goes into a hole made in the
ground.
1. Dhiki
It is a simple machine used to crush and grind grains.
The effort is applied at the end and there is load on the
other side. It is support by fulcrum at the center.
Fig 2. Traditional Dhiki

5. 2. Ghatta
Ghatta is also a traditional machine for grinding
grains. Huge stone disc (Grinder) is rotated by
the kinetic energy of water which strikes the
turbine and gives rotational motion. It makes
the grinding process fast by utilizing flowing
water. In this machine feeding is given same as
from the top hole of disc and keeping the lower
disc stationary. Fig 3. Pani Ghatta
3. Rice huller/ rice husker
Improvement of Rice huller or rice husker is
an agricultural machine used to automate the
process of removing the the outer husks of grains
of rice. Throughout history, there have been
numerous techniques to hull rice. Traditionally, it
would be pounded using some form of mortar and
pestle. An early simple machine to do this is a rice
pounder. Later even more efficient machinery was
developed to hull and polish rice.
Fig 4. Rice huller

6. 4. Modern mixer grinder
Mixture grinder is a modern means of grinding toolls which makes every individual
activities fast and comfortable. There is no need to apply external force as it is operated
by electricity . It consist of motor and the jar with sharp blades with close lid. The vessel
or jar is provided with sharp cutting tools attached with the motors creates rotational
motion at high speed which ultimately crush and grind grains.
Fig 5. Modern mixer grinder

7. EVALUATION
In the past machine were invented to complete the day to day works. As we can see
industrial revolution are also main reason to makes our life easier and comfortable. It
is also believe that the Jato was invented centuries ago , to come to that stage it has
come from a lot of changes.at the past these tools have a lots of importance.
Comparing it with the modern tools is not possible. At that time it was able to solve
may needs of people. It is also a symbol of the evolution of machine. It has come
from a lot of changes to form modern mixer grinder /blender. But nowadays mixer
grinder is able to solve our day to day task ranging from crushing to the grinding
purpose. So I would rate this simple machine with 6 rating out of 10. But I has a lot of
significances during ancient times. These machines are the foundation of modern
machines.

8. RECOMMENDATIONS
From the study we found that the main challenging factor of Jato is that we have to give
more effort by our hands during its operation. To overcome this Jato can be operated same
jato with electricity or either by pedal. By doing this we can preserve its identity as well as
we can also increase efficiency at the same time. Here are the some solutions which can be
adopt to decrease applied effort.
1. Motor operated grinding system
For this we can make fixed the lower disc and
rotate the upper disc with the help of motor,
connected to the shaft with the help of belt. By
doing this there is no need to apply external
human force which makes easier to operate
the system. And it also increase the working
speed. Also adding huge bulk of stone disc we
can also get fine grinned flours.
Fig 6. Modern motor operated grinding system

9. 2. Pedal operated grinding system
We can operate jato from pedal also for this we need to connect the shaft and the
pedal with the help of chain. When we rotates the pedal the upper disc of jato also
moves keeping lower disc stationary which ultimately multiply the effort applied and
start to crush the grains.

10. REFERENCES
[1]"Rice huller", En.wikipedia.org, 2020. [Online]. Available:
https://en.wikipedia.org/wiki/Rice_huller. [Accessed: 27- Jul- 2020].
[2]"The Evolution of Mixer Grinders", Myborosil.blogspot.com, 2020. [Online].
Available: http://myborosil.blogspot.com/2014/04/the-evolution-of-mixer-
grinders.html. [Accessed: 27- Jul- 2020].
[3]2020. [Online]. Available:
https://www.youtube.com/watch?v=RMFq1n_w6Xk. [Accessed: 27- Jul-
2020].