What are the structure, use and maintenance of the theodolite?
Drop In Anchor Drop In Anchor Hebei Qianmu Fastener Manufacturing Co., Ltd , https://www.qmjgjfasteners.com
September 07 06:04:37, 2025
The optical theodolite is a precision instrument commonly used in surveying for measuring horizontal and vertical angles. It consists of three main components: the base, the sighting unit, and the telescope. Each part plays a critical role in ensuring accurate measurements.
First, the base serves as the foundation of the instrument. It includes a central vertical shaft bushing that connects to the sighting unit. A locking Screw on the base secures the connection between the base and the sighting mechanism. This screw must remain tight during use to prevent the parts from separating. The base also features three adjustable foot screws, which are used to level the instrument. At the bottom center of the base, there is a nut that allows the instrument to be attached to a tripod, ensuring stability.
Second, the horizontal circle, or dial, is a circular scale made of optical glass with markings from 0° to 360°. It is used to measure horizontal angles. The center of the dial has a fixed bushing that aligns with the base bushing, allowing the dial to rotate around the vertical axis. A control dial is used to adjust the dial brake and fine-motion screw, providing precise angular adjustments.
Third, the sighting unit sits above the base and rotates on the vertical shaft bushing. Its rotating shaft's geometric centerline forms the vertical axis of the instrument. To control horizontal movement, the sighting unit is equipped with a brake screw and a fine-motion screw. The main components of the sighting unit include the telescope, the vertical circle, and reading mirrors, all mounted on the horizontal axis. These can rotate vertically. A separate telescope brake and fine-motion screw allow for precise positioning of the telescope. Importantly, the fine adjustment only works when the brake is engaged.
In addition to these components, the optical theodolite is equipped with an optical centering device, which helps align the instrument precisely over a point. It also has a leveling device, such as a bubble level, to ensure the instrument is perfectly horizontal. These features make it a reliable tool for surveying tasks.
To use the theodolite effectively:
1. Adjust the tripod legs to a comfortable height for the operator and attach the instrument so that the base is parallel to the top of the tripod.
2. Place the instrument over the desired station point. Use the optical centering device to estimate the center. Adjust the objective lens and eyepiece until the crosshairs align with the target. Move the tripod legs forward, backward, left, and right until the crosshair coincides with the station point, then secure the legs.
3. Extend or retract the tripod legs to bring the leveling vial to a nearly horizontal position.
4. Align the leveling tube parallel to two of the foot screws and adjust them to level the instrument.
5. Rotate the sighting unit 90 degrees and use the third foot screw to level the instrument further.
6. Check the optical alignment again. If there is a slight deviation, loosen the connection screw, reposition the base, and tighten it again. Ensure the bubble level remains centered.
Using the theodolite requires careful setup and attention to detail. Proper calibration and handling are essential for accurate results.
Labels: vertical axis, base, horizontal circle, bushing, maintenance
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