Theodolite and its working mechanism

It is a presentation slide prepared about theodolite and its working mechanism.

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Theodolite And Its Working
Mechanism
Binabh Devkota
[email protected]
Course: Control Surveying (GEOM 202)
Teacher: Er. ShangharshaThapa

2. Introduction
•Theodolite
-Optical instrument
-Angle measurement (horizontal and vertical)
-One of the most used instruments
•Theodolite Survey
-Survey using theodolite
-Traversing, triangulation, trilateration
-Contouring and detail mapping
-Setting out on ground
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3. History Of Theodolite
•First made in 1831 by Philadelphian William J. Young
•Adaptation of the theodolite invented in 1720 by John Sisson of England
-telescope (invented circa 1608)
-Vernier
-device for subdividing measurements by 10ths (1631)
-spirit level (1704)
•Improved versions of Young's transit were still in use for land surveying
in the 1950s
•Are still broadly used
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4. Parts of Theodolite(Vernier)
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S
N
Parts S
N
Parts
1VerticalCircle
10Horizontal Clamp
2Gun Sight
11FootScrew
3Eyepiece
(telescope)
12Objective
4Eye piece
(Reading)
13Micrometer Screw
5Illuminating
Mirror
14Vertical Clamp
6Plate bubble
15Vertical slow
motion
7Reading Slow
Motion
16Optical plummet
8Reading Clamp
17Horizontal circle
9Horizontal
Slow Motion
18Circular bubble

5. Additional Parts (Digital Theodolite)
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1.On Board Battery
2.Keypad
3.LCD Screen
-measured value displayed on screen(no need of
reading eyepiece)
-may have storage capacity

6. Terms Used In Theodolite Survey
•Vertical axis: axis about which instrument can be rotated in horizontal
plane
•Horizontal(trunnion) axis: axis about which instrument can be rotated in
vertical plane
•Line of sight or line of collimation: line through intersection of cross
hairs, optical center of object glass and continued
•Swinging: rotating 180⁰ in horizontal plane about vertical axis
•Transiting: rotating 180⁰ in vertical plane about horizontal axis
•Face left observation: observation done when vertical circle is left to
observer
•Face right observation: observation done when vertical circle is right to
observer
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7. Adjustments Of Theodolite
•Temporary adjustments
-Centering: process in which the vertical axis of the instrument is coincided with the
plumb line
-Levelling: making the vertical axis of instrument truly vertical
-Focusing: adjustment of telescope to obtain clear visibility of image through eyepiece
and objective lens
•Permanent adjustments
-Horizontal axis adjustment: it must beperpendicularto the vertical axis
-Vertical circle index adjustment: it must readzerowhen the line ofcollimationis
horizontal
-Adjustment of altitude level axis: it must beparallelto the line of collimation
-Collimation adjustment: line of collimation/line of sight should coincide with axis of
the telescope
-Adjustment of horizontal plate level axis: it must be perpendicular to the vertical axis
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8. Reading The Angles
•Reading horizontal angle
-the horizontal angle reading is set zero
-the signal(ranging rod) is bisected
(opening horizontal clamp)
-horizontal clamp closed, reading clamp open
and bisected to another signal
-angle noted looking at reading eyepiece, exactly adjusted using micrometer
screw
•Reading vertical/zenithal angle
-Vertical/zenithal angle can be read simply by intersecting
the point and adjusting the micrometer screw
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9. Sources of errors in Theodolite Survey
•Instrument Errors
-Non-adjustment of plate bubble
-Line of collimation not being perpendicular to horizontal axis .
-Horizontal axis not being perpendicular to vertical axis.
-Eccentricity of Inner and Outer axes
-Graduation not being Uniform.
•Personal Errors
•Natural Errors
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10. Inside the theodolite
•Horizontal circle(In horizontal plane)
-graduated from 0⁰ to 360⁰
-can be adjusted
-viewed by reflection to reading eyepiece
•Vertical circle(In vertical plane)
-graduated from 0⁰ to 360⁰
-can’t be adjusted
-viewed by reflection to reading eyepiece
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11. References
•Geodetic Survey, L. (n.d.). Retrieved January 19, 2017, from History of
Surveying -Chicago Area Land Surveying:
http://gslandsurveying.com/history-of-surveying
•surveyhistory.org. (n.d.). The Surveyor's Basic Tools. Retrieved January
20, 2017, from Survey History:
http://www.surveyhistory.org/the_surveyor's_basic_tools.htm
•Punimia, D. B., Jain, K. A., & Jain, K. A. (2005). SURVEYING VOL. I.
Jodhpur: LaxmiPublications (P) LTD.
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