To support large buildings and to secure excavations, a variety of methods of special deep foundation are used. Special deep foundation engineering is of great significance for the construction industry and is one of the most machine-intensive construction methods. To transmit the building loads on stable soil layers, buildings are increasingly built on pile foundations. These piles can be produced in a variety of ways, the most common method being the Kelly drilling method. In this method, a telescopic Kelly bar is used, which is supported on a gearbox attachment and driven by the rotary drive. This gearbox attachment is intended to protect the carrier machine against the regular and irregular loads occurring during operation and to absorb the shocks, which occur when the Kelly bar is lowered into the bore hole while still being telescoped. This should be done explicitly by energy transformation. In this master thesis, a new concept for such a gearbox attachment is developed, or to be specific, proposals for the implementation and application of various machine elements for the gearbox attachment are developed. Special attention is paid to the loads, the requirements and conditions as well as the possible machine elements. With these issues in mind, more appropriate solutions are shown. Furthermore, this thesis considers why it is necessary to develop a new gearbox attachment and why the old version is no longer appropriate. The new gearbox attachment should be able to absorb at least 38 kJ of energy, with a maximum total height of 560 mm. After selecting the most suitable machine elements, they were tested on a, in the course of this master thesis specifically developed test stand, in order to investigate and evaluate their dynamic damping characteristics and thus their applicability for the new gearbox attachment. The tests then showed that the manufacturer’s speciﬁcation could partly be conﬁrmed and it turned out that the plastic damping elements as well as the friction springs were best suited for the new gearbox attachment. Based on the ﬁndings from the tests, two concepts of the gearbox attachment were developed and designed. The ﬁrst concept can absorb 69.9 kJ of energy at an ultimate stress of 597 kN and is 178 kg lighter than the old version. The second concept can consume an amount of 47.1 kJ energy with an ultimate stress of 795 kN and is 155 kg lighter than the old version. Contemporaneous, both concepts can perform a 20 mm larger stroke than the previously used gearbox attachment. Due to the high energy absorption and the simple construction, the ﬁrst concept proved to be the better one.
|Translated title of the contribution
|Elaboration of a concept for a gearbox attachment for compensating regular and irregular loadings
|12 Apr 2019
|Published - 2019
Bibliographical noteembargoed until 26-02-2024
- gearbox attachment
- special deep foundation