Comparator is not a measuring instrument, it is a comparing instrument that means it can compare the measured value of a substance with its actual value.
There are various types of comparators are available in the market, Johansson Mikrokrator is one of them.
It is a mechanical type of simple comparator invented by C.F. Johansson.
Johansson Mikrokrator is also named as Abramson’s movement too
Construction Johansson Mikrokator:
A Johansson Mikrokrator consisted of the following parts:
- Bell Crank Lever
- Twisted Strip
- Cantilever Strip
- Light Pointer
- Slit Washer
Let’s give you a little overview of these parts.
It is the sensing unit, which senses the change of the dimension of any given element.
Bell Crank Lever:
When two arms are meeting at an angle anywhere between 0-360 degree to changes the direction of motion then that type of attachment is called bell crank lever. Generally, we found the angle between the bell crank lever is either 90 degree or 180 degree, however, it can be anywhere between o to 360 degree.
In the case of Johansson Mikrokator, the bell crank lever is used for providing the rotating motion to the twisted strip.
It is a metallic twisted type strip fixed between cantilever strip and bell crank lever. It detects the change in the plunger movement and rotates accordingly.
It is nothing but a metallic strip or plate whose one end is fixed and another end is connected with the twisted strip.
It is a display unit, light pointer shows the value of the change in dimension on a linear scale.
Slit washer is used for the lower mounting for the plunger.
Working Principle of Johansson Mikrokator:
So let’s see how it works?
It works on the principle of button spinning on a loop string.
- When some force is applied to the bottom or tip of the plunger, the plunger moves upward.
- The upper portion of the plunger is connected to the bell crank lever.
- The plunger exerts an upward force on the one arm of the bell crank lever, another arm of bell crank lever is connected at an angle 90 degree with each other, so another arm changes its position due to the upward force by the plunger.
- That causes the twisted strip to further twisted or untwisted.
- Twisted or untwisted results in the change of length of the strip.
- Thus the light pointer rotates by some amount as per the plunger movement and shows the deflection on the linear scale.
Advantages of Johansson Mikrokator:
There are some advantages of Johansson Mikrokator, and those are:
- As there are fewer mechanical components so the instrument is backlash-free.
- Frictionless instrument.
- As it is simple in design so it’s price is comparatively low.
- Magnification capability is more [x5000]
Disadvantages of Johansson Mikrokator:
The disadvantages of Johansson Mikrokator are:
- As this is a mechanical instrument the value of measurement a little bit depends on the environment.
- Due to the slackness in moving parts reduce the accuracy of the instrument.
- Parallax error can happen.
Applications of Johansson Mikrokator:
Johansson Mikrokator is used in various fields like:
- It is used in mass production where we need to check the products in a faster way.
- It is used for inspecting newly purchased gauges.
Let’s See a Video on How to Measure on Johansson Mikrokator?
By changing the length of the cantilever strip we can adjust the magnification of this comparator.
This comparator is made by C.F. Johansson.
Johansson Mikrokator is a type of mechanical comparator.
Abramson Movement is the other of Johansson Mikrokator.
So this is all about Johansson Mikrokator, I hope you like this article if you did then don’t forget to share it on your favorite social media.
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References (External Links):
- Jain, R.K. (2009). Engineering Metrology. New Delhi: Khanna Publishers. ISBN9788174091536.
- Comparator image: By Akhilcs – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22538777
- Feature image: Designed by Author
- Video by: Mattias Kristiansson
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