Theodolite diagram pdf

Watch the Video Below to understand the Theodolite Parts easily. Two spirit levels which are called the plate levels are fixed on the upper surface of the vernier plate. These are at right angles to each other, and one of them is parallel to the horizontal axis. The circular or trough type compass box is attached to the instrument. The circular type is mounted on the upper plate between the A-frame.

While the trough type is attached beneath the scale plate or it is screwed to one of the standards. In modern Theodolites, the tubular type compass is screwed to one of the standards. This Theodolite Part is used to sight distant objects. It is rigidly fixed at the center of a horizontal axis and is perpendicular to it. It can be either rotated in a horizontal plane or in a vertical plane.

The horizontal motion may be measured on a horizontal graduated circle by means of two verniers, and the vertical motion may be measured on the vertical graduated circle by two more verniers. These theodolite parts are rigidly attached to the telescope and moves with the movement or rotation of the telescope. It has two verniers C and D, and the circle is silvered and divided into four quadrants. The line joining zeros is parallel to the line of collimation of telescope when it is perfectly horizontal.

The least count of the vertical circle vernier is usually the same as that of horizontal circle verniers. The clamp and tangent screws of the vertical circle help in setting up of any desired position accurately in a vertical plane.

It is T-shaped and is centered on the horizontal axis of a telescope in front of the vertical circle. Two verniers C and D are provided at the ends of the horizontal arms or limbs called the index arm. The index and clipping arm together are known as the T-Frame. A plumb bob is suspended from the hook fitted to the bottom of the vertical axis.

It is used to center the instrument exactly over a station point. Join Join TheConstructor to ask questions, answer questions, write articles, and connect with other people. Have an account? Log in Now. Join for free or log in to continue reading Remember Me! Don't have account, Join Here. Forgot Password Lost your password? Ask A Question. Double sighting or Do uble entering: double sighting is the way to measure horizontal and vertical angles in face left and face right condition.

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.

Instrumental error: These type of error occur due to construction defects or either due to the permanent adjustments. Personal error: personal error occur due to the instrument not leveled properly or due to the sighting the measurements or note down the readings.

Observations and setting out angles shouldn't be taken in windy conditions. Instrument must be left to adjust to atmosphere conditions.