Dragline excavator
A rope excavator is an earth moving device ( construction machine ) for loosening and transporting soil and rock, in which almost all movements of the excavator tools are carried out with winches and wire ropes. Cable excavators belong to the machine category of excavators and differ from other machines in this category by the cable-mechanical power transmission. In many applications they have been replaced by hydraulic excavators, but rope excavators are still indispensable for certain special tasks (such as digging particularly deep construction pits).
construction
Undercarriage
The lower part of the machine, which is used to move the excavator (mostly using caterpillar chains or wheels) and carries the swiveling upper structure, is called the undercarriage. There are also excavators in which the superstructure is instead mounted on a floating pontoon or a portal structure.
landing gear
The following trolleys are used in dragline excavators to move the excavator:
Slewing ring
The slewing ring of the excavator connects the undercarriage to the uppercarriage and enables it to rotate endlessly. The tipping moments of the superstructure are absorbed by a bearing that is designed either as a double slewing ring or as a roller slewing ring. Compared to the ball slewing ring, a roller slewing ring still needs a centering, the so-called king pin, since the rollers cannot transmit any radial forces. The king pin is firmly connected to the supporting structure of the undercarriage. Furthermore, a slewing ring for guiding the rollers requires either claws or claw rollers as well as tilting sleepers for even load distribution. The excavator also has a toothed ring for swiveling, either with internal or external teeth. A pinion mounted in the superstructure and driven from there meshes with this. In order to transfer the force required for the process from the superstructure to the undercarriage, the center of the slewing gear is the so-called vertical shaft. In the case of rope excavators with a slewing ring, it is located within the kingpin designed as a hollow axle. In the case of mechanical control of the chassis (steering of the chains, brakes), there are further hollow pins that can be moved. Movements (actuation of clutches) can be transferred to the undercarriage by lever mechanisms from the driver's cab in every uppercarriage position. Modern duty cycle crawler excavators no longer have a vertical shaft or mechanical control, as the chassis (as well as the winches in the superstructure and the slewing gear) are driven by hydrostatic motors. The corresponding lines (at least 4) are fed into the undercarriage through what is known as a rotary feedthrough in the center of the slewing ring.
Structure of the undercarriage
The structure of the undercarriage absorbs the forces introduced by the slewing ring from the uppercarriage and transfers them to the chassis. A torsion-resistant steel construction is used for this, which was riveted in the early days of excavator construction and later welded. It is usually designed in cell or box construction. In the case of larger machines, the supporting structure consists of a cylindrical center piece to which X-shaped supports are welded to accommodate the chassis. Furthermore, the axles of the chassis are stored in the supporting structure of the undercarriage and a transfer case transfers the torques coming from the vertical shaft to the drive wheels of the chains (turasse) or the wheel axles of mobile machines.
Superstructure
The superstructure contains all the equipment required for excavation: drive, gearbox, winch, driver's cab and digging equipment. In order to withstand the considerable forces and moments of the excavation operation, all parts of the superstructure are arranged on a massive supporting frame which is solidly connected to the upper part of the slewing ring.
drive
Two different drive concepts are common in rope excavators: the single-motor drive and the multi-motor drive. With single-engine drives, there is a central drive machine (usually a diesel engine) with which all movements of the excavator are generated via gears and clutches. However, if each movement or group of movements is driven by a separate motor, there is a multi-motor drive, which is usually an electric motor, previously also steam engines.
The countershaft
In single-engine rope excavators, the power is transmitted from the engine, which is located in the rear part of the nacelle, through a belt drive , a chain (usually running in an oil bath) or through a spur gear , generally to the so-called countershaft . In addition to this standard version, there are various special designs. The countershaft is used to distribute the drive torque to the various organs to be driven. These can be connected to the countershaft by means of mechanical couplings . The countershaft rotates at a largely constant speed in one direction during the entire operating time. As a rule, up to two consumers can be switched on at the same time. For example, it is possible to drive forward and pivot the superstructure at the same time. Corresponding reversing gears are provided so that the drive torque can also be used in the opposite direction of rotation, for example for swiveling and driving forwards and backwards . In older machines, the countershaft is equipped with plain bearings , otherwise with ball bearings .
Winch
The movements of the grave vessels (primarily spoon , clamshell , diaphragm wall grab and scrapers) and the trailing blade with the wet extraction (eg. As in gravel mining in the Stretch) are at draglines effected exclusively by the train of steel cables with the aid of winches and by gravity . With the classic construction in the case of the single-motor drive, the working movements of the machine are now made possible by opening and closing the clutches between the continuously rotating countershaft and these winches. In the case of multi-motor drives, on the other hand, almost every winch is provided with its own drive motor (steam engine or electric motor); the winches are operated by controlling these drives. With integrated brakes on the winches, the ropes are held under load. Some winches have a self-locking worm gear (e.g. for holding the boom and for crane work). In modern rope excavators, this mechanism is completely replaced by a hydraulic drive for the winches, which enables both sensitive control and locking, so these rope excavators are also a special form of hydraulic excavator. Only in the case of very large rope excavators for the mining industry are direct drives instead of hydraulics; these large devices are electrically driven according to the multi-motor principle.
See also
literature
- Drees, Gerhard ; Link, Roland: Construction machines for civil engineers , Düsseldorf 1969
- This year; Gubany; Hinrichsen: Construction machinery paperback - guide for building practice , Bauverlag 1994
- Kühn, Günter: Handbook of construction operations - organization, operation, machines , VDI Verlag 1999
- Ulf Böge, Stefan Heintzsch: Bagger - The great chronicle of all German manufacturers . 2002
- Ulf Böge, Rainer Volkwein: Weserhütte excavator . 2004
- Dipl.-Ing.HHCohrs, Grube / Holstein: https://www.yumpu.com/de/document/view/20690474/seilbagger-behaupten-sich-bauverlag