"Ortz" System


In figure 1 an outline of the unit with the main elements of which it consists is represented:  sphere, screws and nuts, conical caps and tube.

In table 1 the determining components are presented: screws and spheres, with their maximum design capacities.

The material used in the spheres is a consequence of the particular geometry of the structural system and of the proportions between screw diameter and length of its thread in the sphere.  After numerous experimental tests the most convenient combination of materials of both elements, screw and sphere, has been reached.

As far as the proportion of dimensions between both elements is concerned, the standard size of the sphere for a determined screw, in the low range, is that which avoids possible interference between screws and nuts of contiguous bars with a minimum spatial angle of 45º whilst allowing the total penetration of the thread.  This is compatible with the maintenance of the screw's resistance capacity over the sphere, lessened in no way.  This point has been verified not only from the theoretic perspective, but also in experiments.  In the case of larger scale screws, the geometric limitation of the minimum angle between contiguous bars for the corresponding sphere has slightly increased after determining the sphere's diameter.  In all the cases there is a relation between the size of the normal corresponding sphere and the screw of the largest bar meeting in each of the structure's links.  As an exception, when the largest screws attached to the link are clearly bigger than the rest, there being no geometric or resistance problems, this screw-sphere ratio can be modified.  In no way, however, can the minimum sphere of a link onto which a determined screw is attached, set by the maximum stress, be smaller than stipulated in table 1.

Table 1

As for the nuts, these do not constitute a critical element, since apart from being lodged on the threaded body of greatest diameter, they are two units; one normal and another reduced, thus clearly excessively large.

The ratio of types that are normally used is shown in table 2.  These types are found within a determined group of the proportion between diameter and thickness, which, as we have learnt by experience, is convenient.  This ratio is not unalterable and can be modified according to concrete needs, using either traction or compression types.




Right Metric

Left Metric

Over sphere F-1140 (Ton)

Normal Diam.

Minimum Diam.

16 20 27 36 45 52 64 76

12 16 22 30 37 44 54 64

6,0 11,3 21,8 40,4 62,5 89,4 140,0 202,0

60 76 100 134 150 178 210 250

60 60 76 100 134 150 178 210