Johansson Mikrokator: Construction, Working, Advantages, Disadvantages & Applications [PDF]

What is comparator?

A comparator is not just used as a measuring instrument. It also serves as a device for comparison. It enables the comparison of the measured value of a substance with its true value. Numerous types of comparators can be found on the market, with one of them being the Johansson Mikrokator. This particular comparator, invented by C.F. Johansson, is a mechanical, uncomplicated type. Additionally, the Johansson Mikrokrator is sometimes referred to as Abramson’s movement.

Construction of Johansson Mikrokator

A Johansson Mikrokrator consists of the following parts:

  1. Plunger
  2. Bell Crank Lever
  3. Twisted Strip
  4. Cantilever Strip
  5. Light Pointer
  6. Slit Washer


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 degrees to change the direction of motion then that type of attachment is called a bell crank lever. Generally, we find the angle between the bell crank lever is either 90 degrees or 180 degrees, however, it can be anywhere between o to 360 degrees. In the case of Johansson Mikrokator, the bell crank lever is used for providing the rotating motion to the twisted strip.

Twisted Strip

It is a metallic twisted type strip fixed between a cantilever strip and a bell crank lever. It detects the change in the plunger movement and rotates accordingly.

Cantilever Strip

It is nothing but a metallic strip or plate whose one end is fixed and another end is connected with the twisted strip.

Light Pointer

It is a display unit, light pointer shows the value of the change in dimension on a linear scale.

Slit Washer

A slit washer is used for the lower mounting of the plunger.

diagram of Johansson mikrokator
Diagram of Johansson Mikrokator

Working Principle of Johansson Mikrokator

  • 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 one of the arms of the bell crank lever, and another arm of the bell crank lever is connected at an angle of 90 degrees with each other, so another arm changes its position due to the upward force by the plunger.
  • This causes the twisted strip to further get twisted or untwisted.
  • Twisted or untwisted strip results in a change in the 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 which are as follows:

  • 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 follows:

  • As this is a mechanical instrument the value of measurement a little bit depends on the environment.
  • Due to the slackness in moving parts, it reduce the accuracy of the instrument.
  • Parallax error can happen.

Applications of Johansson Mikrokator

Johansson Mikrokator is used in various fields such as:

  • It is used in mass production where we need to inspect the products in a faster way.
  • It is used for inspecting newly purchased gauges.

Video on How to Measure using Johansson Mikrokator?


How to increase the magnification range of a Johansson Mikrokator ?

By changing the length of the cantilever strip we can adjust the magnification of this comparator.

Who invented Johansson Mikrokator?

This comparator is made by C.F. Johansson.

Johansson Mikrokator is which type of comparator?

Johansson Mikrokator is a type of mechanical comparator.

What is another name of Johansson Mikrokator?

Abramson Movement is another name of Johansson Mikrokator.

Media Credit:

  • Comparator image: By Akhilcs – Own work, CC BY-SA 3.0,
  • Video by: Mattias Kristiansson
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