Classifications of Theodolites

Hello There,
Theodolite is one of the basic instrument which has many uses including traversing. Theodolite is broadly classified into two categories:

  • Transit Theodolite In this type of Theodolite, line of sight can be reversed by revolving the telescope 180 degrees along the vertical plane.
  • Non-Transit Theodolite In this type of Theodolite, the line of sight can not be revolved in the vertical plane.
There are another classifications of the Theodolite:
  • Vernier Theodolites.
  • Micro-meter Theodolites.
Size of Theodolite: This is defined by the diameter of the graduated circle of the lower plate. Common sizes are 8 cm to 12 cm while 14 cm to 25 cm are used for triangulation work or you can say for more precise works.

Main parts of a transit vernier Theodolite are 
  1. Leveling head
  2. lower circular plate
  3. Upper plate
  4. Telescope
  5. Vertical circle
There are some fundamental lines of Transit Theodolite:
  1. Vertical axis
  2. Horizontal axis or Trunion axis
  3. Axis of the altitude bubble or Azimuthal axis
  4. Line of collimation
  5. Axis of the plate bubble
  6. Axis of striding level if present.

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