e-chains for drilling rigs: special flexibility under adverse conditions

• What was needed: E4 e-chain, reverse bend radius system, chainflex® cable
• Requirements: We were looking for an energy supply with high lateral stability that could guide heavy cables and hydraulic hoses
• Industry: Construction machinery
• Success for the customer: Despite the complicated structure of the drilling machine, the hose and cable can be guided safely.

The focus of this application is on the mobile drilling rigs that produce sealing bases at depths of up to 30 meters. They perform the main work in foundation construction and are subject to heavy loads. This applies to travelling to the immediate site over rough terrain and even more so to the actual drilling work. Vibrations and shocks, dirt and moisture, cold and heat place high demands on each individual component.

Under these special conditions, the drilling rigs from KGS Keller prove their worth - even though their design is by no means simple, but extremely demanding. For example, the mast moves in a parallelogram kinematic system. It can be extended straight upwards from its horizontal transport position, but can also be tilted in both directions and brought completely vertically into the drilling position via the front rotary axis. It is also possible to tilt the mast and with it the drill pipe in two axes so that the operator can position the drill pipe at an angle. 
The hydraulic and electric cables must be able to cope with all these movements and be optimally protected. An additional degree of freedom was recently made necessary by new machine safety regulations. The drill head must now be fitted with a protective cage. This in turn has to be tilted in the transport position so as not to exceed the height specification for road traffic.

The designers at KGS Keller utilized this requirement to improve the guidance of the moving cable on the mast. Previously, two hose packages were sufficient. With the additional maneuverability, real guidance had to be provided.

The decision was made in favor of an E4.12 e-chain®, which has also proven itself in other types of construction machinery. This type of chain is exceptionally robust. This is due in part to the rear grip, which ensures high lateral stability. This is particularly important when the mast tilts sideways because the drill head is positioned at an angle. The large diameter of the two hydraulic hoses for driving the drill gives an impression of the forces that the energy chain has to withstand in normal construction site operation. In addition, the hoses, which have a considerable dead weight, move when pressurized.

The signal cables, which are guided in a separate chamber, are less demanding in this respect. However, UV radiation, cold and temperature differences are factors that can have a negative impact on service life. This is why KGS Keller plays it safe here too and uses cables from the chainflex® range, which, like the energy chain, have been developed from the ground up for use in mobile applications and under unfavorable conditions.

The maximum mast height of the KB 6 - the name of the drilling rig, which is currently being manufactured in a small series - is 36 meters with an auxiliary mast. The chain travels on the mast over a distance of 8.10 meters, the trough finishes the basement itself. As the protective cage on the drill head is folded downwards in the travelling position, the chain must be flexible in both directions where the cage is folded through 90 degrees. This is not a problem with the E4 chain: so-called reverse bend radius elements are simply used in the respective zones. The abbreviation stands for 'reverse bend radius'. Three of these elements are installed in the chains of the new generation of Keller drilling rigs.