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“New results concerning ropes of tramways” (1970)

In connection with his professional activities in the field of ropeway engineering – as a lecturer and assistant professor, sworn expert to the courts and public bodies, and technical editor of ISR – Professor Josef Nejez has personally witnessed the developments in the ropeway industry over the last fifty years and can tell many a story.

Created by Josef Nejez

1970 – How it all began

With graduation no longer a distant prospect, students are faced with the question of their future careers. That was my situation at the beginning of 1970, the year of my final exams in Civil Engineering at the Faculty of Civil Engineering and Architecture of the Vienna University of Technology.

Fortunately, the question was soon settled for me: In February 1970, I read an announcement on the notice board of the Institute of Railway Engineering and Transport Economy advertising two vacancies for assistant professorships. I picked up my courage and rang the bell and was immediately admitted to the presence of the head of department, Professor Edwin Engel, which was not something to be taken for granted in those days. After a short interview he agreed to hire me. On March 1st I was given a contract of employment as a research assistant, which was converted into the position of an assistant professor by a ministerial decree issued on May 1st (Labour Day!) after I passed my final exams on April 11th.

What I did not know at the time was that Professor Engel’s research work was mainly focussed on ropeway engineering. The institute’s reputation as a centre of excellence in this field had been established by his predecessor, Professor Eugen Czitary. The textbook Seilschwebebahnen (Aerial Tramways) by E. Czitary, second edition, Springer-Verlag Vienna, 1962, is still relevant today with regard to the theoretical principles, even if the actual engineering of modern ropeways is hardly comparable.

At the institute we assistants on the faculty had little contact with practical ropeway construction and operation. We supervised the students’ course work on the subject of non-rail-based systems, which included ropeways, but contact with ropeway manufacturers, operators and authorities was minimal to non-existent. That was when ISR came into my life. In those days its English title was International Aerial Tramway Review, with Snow Conditioning Technology and Official Mouthpiece of the International Organisation for Transportation by Rope (OITAF) and the Competent Authorities in the subtitle. As the only genuine trade journal in its field, it had an important function for us young academics: It kept us up to date with the latest developments in the entire ropeway industry.

ISR articles from the early days

Now that I can look back on fifty years of involvement with ropeways, I thought it would be a nice idea to select individual ISR articles from the beginnings of my ropeway career and track subsequent developments with regard to the various aspects of ropeway engineering dealt with. In this 2020 issue of ISR, I would like to begin with an article on ropeway ropes written by Dr. E. Müller of Stuttgart, which appeared in issue 3/1970 of the International Aerial Tramway Review. Passages of original text by the author are indented and printed in italics.

Albert’s wire rope

The invention of the wire rope by Julius Albert in 1834 was a prerequisite for the development of the ropeway. The rope had three strands with four iron wires each. In the figure you see the cross-section and top view of an original piece of  Albert rope and the cross-sectional drawing (source: archive of J. Nejez).

“New results concerning ropes of tramways”

The author begins his article with a review of the origins of ropeway engineering and cites the invention of the wire rope by Julius Albert (see box) as the decisive prerequisite for the introduction of ropeway systems. He briefly discusses the development of the monocable and bicable systems before turning to the subject of rope construction. Here is an excerpt from the somewhat unorthodox original English translation:

For moving ropes the following type is carrying through: six-stranded parallel lay worked out in Lang’s lay. The reason for that is that the durability is longer because of the favorable contact conditions of the wires in the strands and the way the Lang’s lay is lying in the groove of a sheave. Normally the Seale construction seems to be most suitable. In special cases the filler wire rope has proved good. In some cases the Warrington construction has led to non sufficient results.

A significant part for the construction of a rope is the core. Mostly it will be a fibre core.

The main purpose of a fibre core is to support the strands radially. For this purpose the core must have enough volume and keep this volume for the life of the rope.

So what has changed with regard to ropeway ropes? Not very much with regard to the basic principles, but although the ropes – and the thinner ropes especially – look much as they did fifty years ago, significant technological developments have taken place in line with the growing demands of the ropeway manufacturers in terms of the higher rope tension needed to cope with increases in carrier weight. While the diameter of a carrying-hauling rope used on a double chairlift would normally be 38 mm at that time, for example, the diameter of the rope of a modern 10-passenger gondola lift is now 56 mm. In terms of rope construction, they are usually Warrington-Seale ropes. (For information on rope construction, you are referred to my article titled The ropes used on ropeway installations in ISR 2/2019, p. 124). Since the mid-1980s, wire diameters for the rope cross-section have been calculated using computer programs that take into account the exact sectional shape of the wires in the rope structure. This ensures, to the best possible extent, the even distribution of pressure between the wires, which is a prerequisite for long rope life.

Other developments in moving ropes include the use of compacted ropes or strands as well as seven or eight-strand, round strand rope. Compacting flattens the outer strands of the ropes and reduces the diameter of the strands, so that rope diameter is reduced while breaking force remains the same. The “rounder” surface also makes for smoother running of the rope over the sheave trains and round the bullwheels. Seven- or eight-strand carrying-hauling ropes offer smoother running, because the valleys between the strands are less pronounced than those of six-strand, round-strand ropes. A rope construction in which the rope surface comes even closer to a cylindrical shape is the Performa rope. Six compacted round strands separated by six extruded synthetic rods are arranged around an extruded polyethylene rod that serves as the core (see Fig 1).

There have also been new developments in rope cores, but they must still meet the same requirements as those described by Müller above. One such development is the use of an elastic synthetic rod as a rope core, in which the strands are evenly embedded during stranding while it is warm. This gives the synthetic rod a star-shaped cross-section. Another rope manufacturer uses a synthetic rope core in combination with plastic inserts or support profiles between the strands to ensure even strand spacing (see Fig 2).

Returning to the article written in 1970, the author has the following to say on the subject of track rope constructions (again quoted from the original English translation):

The construction of the carrying ropes seems to depend on the borders of the different countries. In Germany and Switzerland one exclusively uses full locked coil ropes while Austria and Italy are preferring multi-strand ropes. Obviously this not a question of technical facts but a question of the composition of the supervisory boards. In Germany the use of full locked coil ropes is practically prescribed because this kind of rope has got some advantages: greater corrosion resistance by profiled wire locking, smooth surface, smaller diameter by higher degree of filling, more favorable behaviour at vibration stressing by better conditions of wire contact, better behaviour at braking, and wires of the outer layer easy to replace.

Of course the full locked coil rope has to be well fabricated. Typical manufacturing defects:

  • Cork-screws caused by loosening of the outer layer. Here the outer layer is archlike propping in itself instead of exerting pressure on the core. By that a profiled wire is squeezed out of the outer layer.
  • Rope twist. The reasons for it are not quite known, but maybe the reasons can be found in the different tensions of the wires at stranding and in too small pretension of the rope at the moment when it is pulled out of the stranding machine. Here, too, the rope can form like a cork-screw.
  • Too little lubrication. Here, some of the hollows of the inside of the rope are not completely filled. There will be corrosion in the inner layers and disturbance of the judgement of the state of the rope when magnetic-inductive inspection is done ...

There is little to be added to these comments today, except that the author has not mentioned another advantage of full-locked track ropes: The smooth rope surface means less wear on the linings of the carriage wheels.

The problem of differences between the industry codes of the various ropeway countries depending on the personal views of the staff in their supervisory authorities is a subject I hope to come back to some time in the future. This was one of the reasons for the creation of uniform ropeway standards by Technical Committee TC 242 of the European Standards Institute (CEN). It should also be pointed out that the use of multi-strand ropes as track ropes for new ropeway installations is no longer permitted. Nobody would even think of it today!


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