The Freiberger suspension mining compass comes complete with a mine surveying compass, a protractor tool, a string roll and a cartographic (metallic) baseplate.
The mine surveyor’s hanging compass has a needle with sharp edges to ensure accurate and comfortable reading. A small piece of copper which is used to adjust for inclination is placed on the south end of the needle. The magnetized needle is mounted on a thoroughly centered and polished bearing pin. This allows for almost frictionless movement. The compass needle can be locked using the lateral knurled knob, for instance when the compass is not in use.
The hanging element houses the mine surveying compass itself. The two bearing screws positioned opposite to each other allow for free movement of the compass inside the hanging element’s metal ring. That element as well as the compass are made of light weight, corrosion-resistant materials without magnetic influence. There are two bows attached to the metal ring of the hanging element with prismatic-shaped hooks at each end. The connecting line of those two hooks runs exactly through the middle of the compass.
The protractor tool has the shape of a semicircular arch. The graduation markings start with 0 degree in the middle and then go to 90 degree on each side. A pendulum is attached to a small hole in the center. The pendulum string indicates the inclination angle on the graduated arc. The protractor tool is put onto a string using two lateral hooks.
There are two metal clips in the carrying case that can be used to avoid any slipping of the hanging element or the protractor tool.
The mine surveying compass and the protractor tool are safely stored and transported in a foam-padded plastic case.
In combination with the mine surveyor’s hanging compass, the baseplate is used to draw a chart of the magnetic directions that have been measured.
|Mine Surveyor’s Hanging Compass||graduated circle, diameter||80 mm|
|reading||2° (2 gon)|
|estimation||0,2° (0,2 gon)|
|distance between the hooks||236 mm|
|settling time of the needle||≤ 70 sec|
|accuracy of the needle||± 0,2° (0,2 gon)|
|size||243 x 130 mm|
|Protractor tool||radius of the arc||118 mm|
|reading||0,5° (0,5 gon)|
|estimation||0,1° (0,1 gon)|
Product package includes:
- Mine Surveyor’s Hanging Compass 360° (or 400 gon)
- cartographic baseplate
- protractor tool with pendulum 0° … ± 90° (0 gon … ± 100 gon)
- string roll, length: 50 m
- 2 carrying cases, material: plastic, foam-padded