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DUMPY LEVEL SURVEY- ALL YOU NEED TO KNOW

DUMPY LEVEL SURVEY- ALL YOU NEED TO KNOW

Dumpy level is commonly used leveling instrument to locate the points in same horizontal plane. It is also called as automatic level or builder’s level. Elevations of different points and distance between the points of same elevation can be determined by dumpy level. The telescope is fixed to its supports in dumpy level and hence it cannot be rotated in vertical axis.

The dumpy level is an optical instrument used for surveying and levelling operations. It comprises of a telescope tube, firmly held between two collars and adjusting screws. The complete instrument is staged by the vertical spindle.

The telescope placed on the dumpy level can be rotated amongst the horizontal plane. Relative elevation of survey points on the land can be determined through the dumpy level.

The dumpy level was invented by Willian Gravatt, in 1832. Being a civil engineer, he invented the dumpy level while using Y (Wye) level instrument.

Principle of Dumpy Level Instrument:

The dumpy level operates on the principle by establishing a visual relationship between two or more points, through an inbuilt telescope and a bubble level. The desirable level of accuracy can be achieved through steps.

It is also called through various names such as Surveyors levels, Builders level, Dumpy level or even its pre-historic version “Y(Wye) Level”.

Important Components of Dumpy level:

  • 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.

  • 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.




  • 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.

  • Vertical Spindle  

It is placed in the middle of the instrument. It supports the telescope and rotates in a vertical direction. A vertical Spindle is a conjunction point between a tripod and telescope.

  • 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.

  • 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.

  • 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.




  • 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.

Advantages of Dumpy Level:

  • Operation of the dumpy level is very easy.
  • The cost of the dumpy level is very low compare to theodolite and total station.
  • Very few adjustments are needed to set up the instrument.
  • It gives very high optical power.
  • It gives a very accurate level reading.

Disadvantages of Dumpy Level:

  • It can not measure the vertical angles.
  • Sometimes angular measurement is not that correct.




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