Background of the invention At the beginning of the seventies an excavator named Gradall was introduced in the U. S. A. This type of excavator had great advantages with respect to the known excavator types because it was possible to tilt the last segment of the excavator jib, it means a dipper, to both sides. The inclination angle was about 45° to each side measured transversally to the axis of the excavator jib. This function was enabled due to the new system of fastening of the excavator jib and due to a pair of gears driven by a hydraulic pump. This revolutionary excavator type enabled to increase the application possibiiities of such machine, because the excavator could smooth incline plains during the terrain works without the need to be positioned perpendicularly to the smoothed plain as it was necessary before. Nevertheles this excavator was too dimensional, expensive and because of its robustness not suitable for the european conditions.

Similar excavator named Satum was constructed later in the previous Czechoslovakia. It was a self-propelled machine with a tilting dipper with the inclination angle of 45° to both sides. It was similar to the Gradall in all aspects above all with its telescopical jib, quick-clamping mechanism for exchange of tools e. g. dippers of various types, log tongs, digging punches etc.

This machine was suitable for european conditions, nevertheies in the eigties an excavator of a new generation was constructed in the factory Detva in Slovakia. It is a machine with different and original system of a tuming head of the jib. The principle is that it is possible to tum the head about 360° without any limitation. The interest for this excavator was immense. The producer put the machine on the chassis of a truck or on a belt chassis. The machine named UDS is a part of the equipment of many construction firms. The usefulness of this excavator is really big. It may be used for many kinds of work in the terrain or e. g. by cleaning of the construction site etc. The disadvantage was lower digging power in a comparison with excavators in the same class and the reliability of the machine parts does not reach the quality of the competition. But the competition does not have a tuming head. From that reason every bigger construction firm has for disposal an excavator with tuming head and reliable excavators of the classical construction.

The aim of the invention is to enable to combine advantages of both types of excavators in one machine. It means to enable to fasten a turning head on a standard quality and powerful excavator.

Technical characteristics of the invention The above mentioned insufficiencies are up to a considerable degree eliminated by a reducing holder of a tuming head with a dipper on an excavator jib according to the invention the subject matter of which is that it consists of at least two bearing plates connected with at least one cross-plate wherein the bearing plates are on one end provided with a flange and the cross-plate is on one of its faces ended before a set of holes, which are provided on both bearing plates coaxially in the perpendicular axis to the longitudinal plane of the bearing plates and the set of holes consists of at least two holes bored coaxially in the longitudinal plane of the bearing plates and of at least one stabilization hole arranged extra axial with respect to the axis of the two holes and between them. In the area of the holes the reducing holder has a shape of a fork. The reducing holder is put on the terminal segment with the fork in that way, that the holes on the terminal segment of the jib are coaxial with the holes on the bearing plates and into the stabilization holes of both pieces the tuming pin is inserted. In this way a firm connection between the terminal segment and reducing holder is provided.

In a preffered embodiment the cross-plate is on one of its ends connected to the flange. By this way the fastening of the tuming head on the reducing holder is more stable.

Description of the drawings The invention will be illustrated in reference to the drawings where Figure 1 illustrates a view on an excavator of the clasical type with a normal dipper, Figure 2 shows a detailed view on the known tuming head on the last segment of the jib and Figure 3 illustrates the reducing holder according to the invention.

Examples of the invention embodiment Figure1illustratesaviewonanexcavator1oftheknowntypeprovidedw ithajib2<BR> whichconsistsofamainshoulder3andaterminalsegment4.Thefreeend ofthe<BR> terminalsegment4isprovidedbyanendinghole5inwhichabearingpin6 ofa<BR> dipper7isinserted.Thisbearingpin6representsanaxisaroudwhicht hedipper7<BR> istilting.Inthedirectiontotheanchoredendofthewholejib2intheb odyofthe<BR> excavator1thereisananchorhole8withananchorpin9ontheterminals egment<BR> 4.Bothholes5and8areboredontheterminalsegment4andtheyareposit ioned on an axis x. A supporting lever 10 is put on the anchor pin 9 and this lever 10 is projectinginthedirectionawayfromthebodyoftheexcavator1.Thesu pporting<BR> lever10isontheotherendprovidedwithaleverhole11inwhichatuming pin12 is inserted. The above mentioned holes 5 and 8 are provided in both elongated walls of the terminal segment 4. There is also an identical couterpart to the supporting <BR> <BR> lever10intheformofthesupportinglever10'andbothlevers10,10'ar e<BR> connectedtogetherwiththetumingpin12.Tothistumingpin12anendof the piston 14 of a hydraulic cylinder 13 is fastened. Due to the pulling out and in of the piston 14 the tilting of the dipper 7 aroud the bearing pin 6 is regulated. This is also a description of an embodiment of a known excavator 1.

Figure 2 illustrates also a known solution-the embodiment with a tuming head 15 <BR> <BR> fastenedtotheendofthetelescopicterminal16ofajib.Thetuminghea d15is<BR> providedwithadipper17,whichcanbetuminthescopeof360°.<BR& gt; <P>Figure3illustratesareducingholder18ofatuminghead15w ithadipper17onan<BR> excavatorjib2ofanexcavator1accordingtotheinvention.Thereduci ngholder18<BR> consistsoftwobearingplates19,20connectedwithatleastonecross- plate21but<BR> notalong the whole length of the bearing plates19,20.Toonefacesofthebearing<BR> plates19, 20aflange22forthefasteningofthetuminghead15isprovided.Onthe other faces of the bearing plates 19,20 two coaxial back holes 23 on the axis x'are bored. Coaxially with them and closer to the flange 22 two coaxial front holes 24 through the bearing plates 19, 20 are bored. The distance between the back holes 23 <BR> <BR> andfrontholes24ontheeachbearingplates19,20isthesameasthedist ance<BR> betweenendingholes5andtheanchorholes8onthewallsoftheterminal segment<BR> 4.Thecross-plate21isfastenedtothebearingplates19,20betweenth eflange22<BR> andthefrontholes24.Intheareaoftheholes23,24hastheholder18sha peofa<BR> fork.Theholes23,24arecoaxialintheaxisx'inthelongitudinalplan eofthe<BR> bearingplates19,20. On theothersideeachoftheholes23,24onthebearingplate<BR> 19iscoaxialintheaxisyintheperpendicularplanewiththeanalogica lholes23,24<BR> ontheoppositebearingplate20.Betweentheholes23and24extraaxial withthe<BR> axis x'astabilizationhole25boredonthebearingplate19.whichisagainc oaxial<BR> intheaxisywithanalogicalstabilization hole25ontheoppositebearingplate20.<BR> <P>Thedistancebetweenthecentresofthebackholes23andthes tabilizationholes24 is the same as the distance between the centres of the anchor hole 8 on the walls of the terminal segment 4 and the tuming pin 12.

Intheconcreteembodimentthereducingholder18isputonthetermi nalsegment4<BR> withtheforkinthatway,thattheholes5,8arecoaxialwiththeholes23 ,24andinto<BR> thestabilizationholes25thetumingpin12isinserted.Thetumingpin 12neednot<BR> tobeprovidedwiththepiston14.Alsointotheholes23,24resp.5and8t hepins6<BR> and9areinsertedsothestabilizatedpositionofthereducingholder1 8onthe<BR> terminalsegment4issecured.Thetuminghead22withthedipper17isfa stenedin<BR> theusualmanner.Afterthisoperationtheexcavator1ofastandardcon structionis<BR> abletoexercisealltheoperationwhicharenormallypossibleonlywit haspecial excavator with the tuming head 15.