Components parts of Dumpy Level - TS

 


A dumpy level is an optical surveying instrument used to establish or verify points in the same horizontal plane. It consists of a fixed telescope rigidly attached to a leveling head, supported by a vertical spindle and a tripod. 

The essential component parts of a dumpy level are categorized into three main sections: [1]
1. Telescope Assembly
  • Objective Lens: The front lens that gathers light from the target (usually a leveling staff) to form an image.
  • Eyepiece: The lens the surveyor looks through to view and magnify the image and crosshairs.
  • Diaphragm: A small ring inside the telescope that holds the crosshairs (horizontal and vertical) which align with the target.
  • Focusing Screw: Used to adjust the clarity of the image on the crosshairs based on the distance to the staff.
  • Sun Shade: A hood placed over the objective lens to block glare and shield the glass from dust or rain. 



2. Leveling and Orientation
  • Bubble Tubes (Spirit Levels): Typically includes a longitudinal bubble tube (parallel to the telescope) and a cross bubble tube (perpendicular) used to ensure the instrument is perfectly horizontal.
  • Compass: An optional circular compass mounted on the instrument to determine the magnetic bearing of a line.
  • Vertical Spindle: The vertical axis that allows the telescope assembly to rotate horizontally. 


3. Base and Support
  • Levelling Head: Consists of parallel plates (Tribrach) and foot screws used to precisely center the bubble levels.
  • Foot Screws: Screws used to tilt the instrument and adjust the leveling head until the bubble is centered.
  • Tripod: A three-legged, adjustable stand that provides a stable base for the instrument on uneven ground

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