Dumpy Level Surveying : Principle, Parts, Use, Precautions, Advantages & Disadvantages
Table of Contents
In this article, we will discuss the dumpy level.
1. Introduction
The dumpy level may be defined as an optical instrument utilized for surveying and leveling operations. It contains a telescope tube, firmly placed between two collars and adjusting screws. The complete instrument is presented by the vertical spindle. The telescope kept on the dumpy level can be rotated along the horizontal plane.
The relative elevation of survey points on the land can be calculated with the help of the dumpy level. In 1832, Willian Gravatt invented the dumpy level. He was a civil engineer, he invented the dumpy level while working with the Y (Wye) level instrument.
2. Principle of Dumpy Level Instrument
The dumpy level works on the principle by making a visual relationship between two or more points, through an attached telescope and a bubble level. A wise level of accuracy can be attained through these steps.
It is also known as Surveyors levels, Builders level.
3. Parts of Dumpy Level
1. Telescope
The telescope in the dumpy level is utilized to compute distant objects in the line of sight. The telescope is built with a vertical spindle, giving the telescope to be movable in different directions.
The telescope comprises different elements, all the elements are as follows:
Eye Piece
It contains a magnifying glass and is essentially utilized by the observer.
Objective Piece
it is placed at the farther end of the eyepiece. It contains both a convex lens and a concave lens.
Diaphragm
It is provided in the outline of the eyepiece with the cross of dark metal. They are given to intersect the objects.
Focusing Screw
They are kept to align the focus and image clarity of the object.
Ray Shade
It prevents sunlight from passing through the objective lens.
2. Bubble Tubes
They are provided to align the level of the instrument. Bubble tubes in horizontal and vertical directions within a built-on dumpy level. The instrument is perfect to survey when both the bubbles are in the middle.
3. Compass
Compass is utilized to know the magnetic bearing of the line of the path of the survey. The compass contains a pointer that shows directions. The compass is ranged for the magnetic bearing in the north direction.
4. Vertical Spindle
It is placed in the middle of the instrument. It supports the telescope rotates in a vertical direction. A vertical Spindle is a conjunction point between a tripod and telescope.
5. Tribrach
Tribrach is parallel to the leveling head and essentially utilized to manage the horizontal level of the instrument. The trivet is attached through foot screws.
6. Foot Screws
The foot screws are utilized to calibrate the instrument through the bubble tube. By adjusting foot screws one can calibrate the tribrach plate. To make sure the bubble is in the middle, foot screws are used.
7. Levelling Head
Leveling head is also known as a trivet, it contains two triangular plates lined up parallel to each other. It contains groves to support foot screws.
8. Tripod
Tripod is the platform for supporting the complete dumpy level. Tripod Contains three legs prepared of hollow steel sections or light or hardwood. Steel shoes kept at the foot make sure that the tripod is unmoveable with small jerks.
| Read Also: Total Station in Surveying |
4. Use of Dumpy level
It has huge importance in the field of surveying a construction site. The level of accuracy and handiness of the dumpy level has been the best choice for the surveyors. The uses of dumpy level are as follows:
a. It is used the main reason for executing leveling on a construction site is to make the field level smooth.
b. It is used to calculate the differences in height between two points.
c. It is used to calculate the height and distance of various locations of surveying land through the principle of relativity.
d. It is used to calculate the following distance amongst various points on the surveying land.
e. It is used to set out levels and inclined surfaces for construction.
f. It is used to prepare a contour on land.
5. Precautions While Setting Up Dumpy Level
All the important precautions should be taken while handling the instrument otherwise the error will be high. The precaution that needs to be taken while working with a dumpy level.
a. The tripod should be managed to eye height.
b. Try to neglect to touch, push, or apply pressure on the tripod while moving around or working.
c. When moving around the tripod, make sure you don’t trip over the legs.
d. Watch the bubble every time, change in a bubble can give inaccurate results.
e. Neglect setting up the instrument on soft ground.
6. Advantages of Dumpy Level
The advantages of dumpy level are as follows:
a. Simpler construction with minimum movable parts.
b. Minimum adjustments are to be made.
c. High rigidity makes it versatile for long-duration surveys.
d. High optical power.
e. Cost-efficient in terms of usage on diversified construction sites.
7. Disadvantages of Dumpy Level
The disadvantages of dumpy level are as follows:
a. Bounded to the site with horizontal angle measurement
b. There can be a certain level of inconsistency in the values collected.
| Read Also: Topographic Surveying |
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