Together with the Austrian rope manufacturer Teufelberger Holding AG, Liebherr is developing a new type of high-strength fiber rope for hoisting operations. This project is based on a systematic cooperative venture between Liebherr engineers from various divisions, including Liebherr-Components Biberach GmbH, as well as the three Liebherr manufacturing plants for tower cranes, mobile and crawler cranes, and maritime cranes.
The practical requirements of cranes with increasingly higher hoisting heights and maximum load capacities require a realignment in the rope and crane design. The high-strength fiber rope developed after many years of collaborative work between Liebherr and Teufelberger is based on the vast experience of Liebherr in rope applications and winch technology for multi-layer spooling and the in-depth know-how of Teufelberger in the development and manufacture of fiber and steel ropes.
The use of high-strength fiber ropes offers huge potential. In comparison to steel ropes, the newly developed rope is significantly lighter and is more durable. The load capacities of the cranes can be increased thanks to the reduced weight of the rope, which also allows the mass of the hook block to be reduced significantly. In addition, the ropes no longer need to be lubricated.
Reduced weight of rope increases load capacities of cranes
The weight of the high-strength fiber rope is up to 80% less in comparison to a steel rope. This saving can be reallocated directly to the load being lifted. It is also possible to use lighter load hooks. The load capacities of the cranes are thus further increased.
Another advantage is the simplified assembly and disassembly of the crane thanks to the reduced weight of the rope. Fiber ropes can often be mounted on the crane by hand and without any reeving winches. Reeving around the hook block is also quicker and easier.
Long service life improves crane availability
The high-strength fiber rope developed by Liebherr and Teufelberger is extremely wear-resistant and permits a high number of bending cycles. It lasts much longer in comparison to the steel rope. The higher service life can reduce the number of rope changes.
The crane operator is able to easily and safely identify when the rope needs to be changed. Liebherr adopts a redundancy strategy here in order to be able to easily recognize the discarding state for all rope constellations and applications through the entire service life. The discarding state is mainly identified when the coat of the rope is clearly worn and the wear indicates that the rope is ready to be discarded.
The fiber rope developed by Liebherr and Teufelberger can cut in the lower layers repeatedly without causing damage. The winding pattern of the new fiber rope is comparable to the winding of a steel rope. If the lower layers are preloaded less than the upper layers, the new fiber rope behaves however more tolerant than the steel rope. In the case of cutting in the lower layers, it frees itself, unlike steel ropes that usually interlock.
In order to achieve controlled wear of the fiber rope, Liebherr relied on the proven Lebus spooling system. A proper winding pattern at the rope drum minimises wear and increases the service life.
En route to practical application
Liebherr is currently testing the new high-strength fiber rope. Firstly, various crane applications are being simulated at the rope test bench in Biberach/Riss (Germany). Since September 2015, field tests have been carried out on various cranes of Liebherr-Werk Ehingen GmbH, Liebherr-Werk Nenzing GmbH and Liebherr-Werk Biberach GmbH.
The high-strength fiber rope will be launched in the market in two stages. Initially the steel ropes of tower cranes, mobile and crawler cranes, as well as maritime cranes, will be replaced with high-strength fiber ropes. In the second stage, with mobile cranes, for example, the weight saved at the hoist rope is used to reinforce the supporting structure. This permits a further increase in the load capacity.
At bauma 2016, Liebherr will present the new development in a technology pavilion at its outdoor exhibition stand. The exhibit of the LR 1100 crawler crane will also be equipped with a high-strength fiber rope. Rope drums with fiber rope will also be showcased for the LTM 1750-9.1 mobile crane and the 172 EC-B 8 tower crane.