Structure and features of theodolite

The structure of theodolite is a very important aspect for builders. After all, a theodolite is a device whose purpose is to change the angles of the earth's surface vertically and horizontally.

Theodolite Varieties

Varieties of theodolites.

This device was the first invention of mankind, performing a similar function, but such samples were somewhat primitive. To date, this device is equipped with a level and variants of the electronic form. They allow you to get the most accurate results. The convenient structure of the modern theodolite allows you to conduct a survey easily and naturally with the absolute simplicity of the device.

In order to properly measure the plane, you must have the appropriate knowledge and skills. Also, the maximum accuracy of the work is possible only in alliance with computer technology. However, having shown diligence and patience, it is quite easy to understand the scheme of operation of this device.

Diagram of a typical theodolite

Diagram of a typical theodolite.

It is known that when creating a project for the construction of any building, geodetic works are carried out first. The purpose of such events is the accuracy in the placement on the object plane and the compliance of the specified dimensions with the developed plan. As the measurement works are completed, the foundation is laid out, partitions are erected, and work on the finishing of the room is carried out. Theodolite as a construction device is simply necessary for any kind of construction. Such devices are actively used in the process of research, in geodesy, polygonometry. They help to carry out repair work on automobiles, various designs, instruments, and machines belonging to high-tech versions.

Optical-view devices are equipped with reading points that help to accurately calculate the location of coordinates. The mechanism of the electronic type is equipped with a display and functions of imprinting in the memory of the set coordinates.

The description of the theodolite

A theodolite is a U-shaped device, equipped with a stand and telescope. The device has the following elements: a circle of horizontal and vertical views, a viewing tube, a level of a cylindrical shape, and lifting legs.

The main parts of the first devices were characterized by the fact that in the middle part of the circle at the end of the needle they had a linear device. It moved freely on a sharp object, like a compass rail. The gauge had cuts to which threads were drawn, serving as indices of index values.

Technical characteristics of theodolites

Technical characteristics of theodolites.

The middle of the measuring circles was located in the upper part of the corner and was clearly fixed. When moving the measuring device, it was connected to the angle of the right position. After that, the ruler was connected to the other side of the corner. The dissimilarity of the first and second reports equals the angular value. The moving ruler is called the "limb".

Today's samples of such devices differ structural elements:

  1. Connecting an alidade with corner points requires the use of a viewing tube. It moves easily relative to the angle and height indicators.
  2. The direction of the limb assumes the presence of a counting device.
  3. The device is equipped with a reliable iron rim.

The rotational movement of the limb and alidade is based on the coordination of their work with the help of clamping and guide screws. Their movement depends on the axial system. It is possible to install a theodolite on the ground by using props. The connection of the middle of the moving ruler with plumb lines crossing the top of the azimuth of interest is carried out by a thread plumb line.

For the elements to be measured, the sides are transferred to the surface of the limb by a movable planar structure of a vertical form, known to all by the name “collimation plane”. It consists of the sight axes of the viewing tube as it revolves around itself. This line passes through the middle of the thread networks and the center of the device optics.

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The main elements of the device

The main parts of theodolite:

Using theodolite

During construction theodolite is used to control the level of the building.

  1. The limb is a sphere with a graduation from 0 ° to 360 °, which allows to measure angular zones, becoming a kind of active measure.
  2. Alidada is a movable part of the instrument that has a reference system relative to the limbus and a viewing tube. Most often, the spinning element is called alidade.
  3. The viewing tube is fixed on the supports.
  4. The axial device helps the alidade part and limb to rotate along the vertical axis.
  5. A vertical sphere measures angles of a similar appearance.
  6. The support mechanism, equipped with screws in the amount of 3 pieces.
  7. Screws for clamping and pointing, located on the movable part of theodolite.
  8. Tripod mechanism, equipped with a sheer hook, a surface plane for fixing the device and having a screw.


  • limb permutation screw;
  • level with alidade horizontal circle;
  • vertical circle level;
  • pipe focusing screw;
  • eyepiece microscope reading device.

Theodolite moves in the following ways:

  1. Moving the visual device.
  2. Torsion of alidade and limb. This action is associated with fastening screws clamping and suggestive nature.

The movement of the limb may also be different. Thus, such a movement is often associated with the action of two screws, fastening the part in question with alidade.

Most modern devices are equipped with a telescope, combining the sides of the corner and alidade. Its movement is relative to the azimuth and height. So that the device is most reliably protected from accidental impacts, it is placed in a special metal case. He is not afraid of any mechanical effects, as well as unexpected falls.

The axial device allows you to smoothly turn the limb and alidade, the screws take control of the torsional moment itself.

To fix the device on the ground, you need to prepare a special tripod. The connection of the plumb line and the middle of the measurement circle is carried out with a thread plumb.

The moving collimation plane, which appeared as a result of the rotation of the sight axes of the viewing tube near the middle.

Basically, a theodolite is a device that requires well-coordinated and precise work. Especially it is demanding for beginners. Therefore, before starting work, you should familiarize yourself with the instructions.

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The sequence of installation of the device

Theodolite Tripod

To properly install theodolite, a special geodetic tripod is needed.

  1. Theodolite is fixed on a tripod, in some cases calibration is performed.
  2. 2 any points of measurement are determined.
  3. A focusing screw or diopter ring allows the pipe to be guided to selected landmarks.
  4. The viewing device moves to the point in question. The horizontal circle calculates the desired indicators.
  5. By loosening the fixing screw, the pipe moves clockwise to another point, the numbers are remembered.
  6. The visual device is translated through the zenith. Measurements are carried out similarly. As a result, the average value of all the readings is acquired.

The use of a theodolite involves the introduction into practice of circular reception. This method is actively used in the case when it comes to measuring from one point. You can do it like this:

  1. The device is placed just above the point. The limb in this case moves to zero marks.
  2. The alidade rotates, combining the zero readings of the microscope with the values ​​of similar pressure figures on the measuring wheel. Then the screw is slightly loosened, the alidade is fixed, and the pipe is directed at the object.
  3. The locking screw is firmly fixed, then the obtained values ​​are calculated.
  4. Further, in the process of moving the viewing element, it is directed to the object under study.
  5. Alidada returns to the initial position, and similarly, readings of another plan are made.
  6. Calculated average value taking into account errors.

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Optical and electronic theodolites

In the recent past, such devices were used by geodesists. Now there are enough analogues that serve as a good replacement for such devices. They are optical and electronic. Automatic theodolites can take readings. They are equipped with a liquid crystal screen, you can see all the necessary information on it. Such a device is distinguished by maximum accuracy and high speed. The visibility provided makes it easier to understand its dimensions. Electronic types of such devices do not contain storage devices.

Among the shortcomings of such structures it is necessary to allocate the subjection to electricity. In this case, the optical device will become an indispensable assistant. It does not depend on the level of battery charging.

At the time of selecting the device, you should check that the device has a warranty obligation and detailed instructions. It is necessary to carefully study the acquisition of the device. The modern market has a large variety of such devices, each of them has its own value.

Choosing the device you like, you can not worry about getting the wrong values ​​of the coordinates and heights of the studied objects.

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