Component parts of Theodolite with explanation of each part and functions
THEODOLITE
OBJECTIVE: The main objective of theodolite is to measure both the horizontal and vertical angles.
*Based on transiting theodolites are of two types:
1.Transit surveying
2.Non-Transit surveying
NOTE: Transiting mean rotating,as theodolite can be rotated in horizontal and vertical planes it is called transit theodolite.And which can be used only to measure horizontal angles it is called non-transit theodolite.
COMPONENTS PARTS OF THEODOLITE:
1.HORIZONTAL ANGLE;Measured with horizontal scale of vernier A&B.Horizontal angle measures from (0-360)°.vernier A&B is attached to upper plate A&B.
Mainscale-least count __20',0°,0'{20minutes}
Vernier scale-least count__20",0',0"{20seconds}
2.VERTICAL ANGLE:Measured with vertical scale of vernier C&D.It ranges from(0-90)°
3.UPPER CLAMP AND LOWER CLAMP:
*Based on transiting theodolites are of two types:
1.Transit surveying
2.Non-Transit surveying
NOTE: Transiting mean rotating,as theodolite can be rotated in horizontal and vertical planes it is called transit theodolite.And which can be used only to measure horizontal angles it is called non-transit theodolite.
COMPONENTS PARTS OF THEODOLITE:
 |
| PARTS OF THEODOLITE |
1.HORIZONTAL ANGLE;Measured with horizontal scale of vernier A&B.Horizontal angle measures from (0-360)°.vernier A&B is attached to upper plate A&B.
Mainscale-least count __20',0°,0'{20minutes}
Vernier scale-least count__20",0',0"{20seconds}
2.VERTICAL ANGLE:Measured with vertical scale of vernier C&D.It ranges from(0-90)°
3.UPPER CLAMP AND LOWER CLAMP:
- When upper clamp screw is tightened,but lower clamp screw then verneir scale readings don't change and we can measure main scale readings.
- When lower clamp is tightened,but upper clamp is loose than we can measure vernier scale readings.
4.FACE LEFT CONDITION :
- If the vertical circle left side on the observer than the theodolite is in face left condition
- In this condition telescope is normal,bubble is upwards.
5.FACE RIGHT CONDITION:
- If the vertical circle is right side to the observer than the theodolite is in face right condition
- Tn this condition telescope is inverted,bubble is downwards
6.SWING TELESCOPE:
- It is the process of turning the telescope in horizontal plane about vertical axis.
- Rotation of telescope in clockwise direction is called right swing.
- Rotation of telescope in anti-clockwise is called left swing.
NOTE: Face left condition with right swing is best combination.
7.TRANSITING THE TELESCOPE:
- It is the process of rotating the telescope of theodolite in vertical plane about horizontal axis that is rotating in y-direction about to the X-axis is called transiting the telescope
- It is also known as reversing or plunging.
8.Double sighting or Double entering:
- double sighting is the way to measure horizontal and vertical angles in face left and face right condition.
- In an technical way it is the process of measurement of horizontal and vertical angles in both the conditions(FL&FR).
- It is also known as transverse or elevation axis.
- It is the plane of rotation of a telescope in vertical plane.
- It is axis of rotation of the telescope in the horizontal plane.
ERRORS IN THEODOLITE:
1.Instrumental error: These type of error occur due to construction defects or either due to the permanent adjustments.
2.Personal error: personal error occur due to the instrument not leveled properly or due to the sighting the measurements or note down the readings.
3.Errors due to natural causes:
- Observations and setting out angles shouldn't be taken in windy conditions.
- Instrument must be left to adjust to atmosphere conditions.
- If refraction is a problem than reading must not be taken.
- The instrument must be kept in shade while working in hot sunshine.
- Setting out up the instrument on the soft ground must be avoided.
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