Original Leica High Accuracy GDF121 Pro Tribrach w/o Optical Plummet

Model: GDF121

Specifications:

Torsional Stiffness: <1"

Weight: 780g

Features:

1. High Accuracy
2. Maintenance Free
3. Individually Tested
4. Suitable for all high angular accuracy requirements.
5. Torsional stiffness <1"
6. Weight: 760g

The ideal tribrach for your application
All original tribrachs comply with the strict specifications and quality standards of Leica Geosystems. Your choice should ideally be made according to your ­individual accuracy requirements.

Professional 5000: Hysteresis maximum of 1" (0.3 mgon) or better
Professional 3000: Hysteresis maximum of 3" (1.0 mgon)
Professional 1000: Hysteresis maximum of 5" (1.5 mgon)

Introduction:

The accuracy with which a tribrach returns to its starting position once the instrument has stopped, is called torsional rigidity or hysteresis. This hysteresis is the relative movement between the top plate and the base plate of a tribrach that occurs through the rotation of a TPS instrument. The hysteresis has direct influence on the angular accuracy of the instrument – and that speaks for the original. To optimize the hysteresis as Leica Geosystems has done is complex and calls for the highest precision: a movement of the top plate to the base plate of 0.3µm corresponds to an angle error of 1". Especially motorized instruments with their high acceleration and brake power require tribrachs with very high torsional rigidity.

The foot screws are maintenance free and have a larger diameter. This allows for fine adjustments, even when wearing work gloves under difficult environmental conditions.

Leica Tribrach

Similarly to the stability of the tripod, that of the tribrach is a significant factor in measurement accuracy. The torsional rigidity, the most important criterion of a tribrach, is constantly controlled and tested during its production. The maintenance-free foot screws of the Leica Geosystems tribrach provide movement that is always smooth and free of play, even after years of use. The precise alignment of the support area to the base plate of the instrument assures extremely accurate forced centring. The optical plummet is so robust that the need for adjustment during the entire lifetime of the tribrach is practically unnecessary. Its construction predestines the tribrach for all applications, including extreme temperatures and high dust and humidity.

The torsional rigidity of the original
The accuracy with which a tribrach returns to its starting position once the instrument has stopped, is called torsional rigidity or hysteresis. This hysteresis is the relative movement between the top plate and the base plate of a tribrach that occurs through the rotation of a TPS instrument. The hysteresis has direct influence on the angular accuracy of the instrument – and that speaks for the original. To optimise the hysteresis as Leica Geosystems has done is complex and calls for the highest precision: a movement of the upper plate to the lower plate of 0.3μm corresponds to an angle error of 1”. Especially motorised instruments with their high acceleration and brake power require tribrachs with very high torsional rigidity.