Cable with less rigidity will have originated accident from the Glory Elevator

The type of elevator cable was changed six years ago. The fact that Carris has not considered a different fixation when he made the changes have contributed to the accident.

The preliminary report of the Aircraft and Railroad Accident Prevention and Investigation Office (GPIAAF) has given some clues about what may have given rise to the Glory Elevator accident.

As it quotes, the cable loosened, the brakes did not act and the carriage could not stand the clash and was totally destroyed at 60 km/h. Everything went badly.

The first finding of GPIAAF in the report is that “the cable that joined the two cabins gave in to their fixing point within the upper trambolho from cabin nº 1 “.

But, at the origin of the problem, it will have been cable type change Used non -elevator.

Based on the report, experts heard by Expresso point out, in particular, a change made six years ago, when a cable fully steel was replaced by one formed by Six steel strings with “soul in fiber”.

The core of the cable then came to consist of a “Cord” that “deform” irreversibly when it was tight and continued to deform over the months, losing volume and leading the cable to release.

This then made the cable that supports the lift was released from the strokethe piece where it is tied.

“There was effectively the exchange of the cable that was steel and became a fiber soul (possibly polymeric), changing the interior (core) to a much lower stiffness.

“This implies a system change “After a change of these, the mooring must be rethought, explained Pedro AmaralMaterials Engineer.

Fernando BrancoFull Professor of Civil Engineering at Instituto Superior Técnico (IST), agrees with this thesis: “If the cable moves, the tie system must also be tested.”

New more fragile cable. With steel would not happen

With the new characteristics, over time, The cable will have lost resistance to the squeeze made in the trambolho.

In addition, the expert explained, there are other factors to take into account: the high temperatures potentiated by vibration and friction of materials; and the fact that the cable consists of 2 elements with different physical behaviors.

“When you squeeze at first, everything is tight, but then you need to look at the time factor. There are dilations, vibrations and the compatibility between both materials is different than if it were steel with steel,” he said. “A fiber cable of soul begins to deform. At one point it is no longer tight”He added.

As Pedro Amaral explained to the weekly, “when there is assignment, there is a deformation that is irreversible.

However, The same would not happen if the cable was completely in steel.

“Absolutely inconceivable” brakes

According to GPIAAF, the Header and then fired the pneumatic brake and brake manal.

However, according to the report, in the existing configuration, the brakes do not have sufficient capacity to immobilize the moving cabins when they are not connected by the cable.

In an opinion article quoted by the Express, Henrique Oliveira and Luís Meloteachers of the IST mathematics and physics departments, point out these “Severe conception errors”as “perhaps acceptable in the early twentieth century, but absolutely inconceivable these days ”.

After all, the “brakes never had the necessary capacity to autonomously immobilize vehicles in case of cable failures ”, although experts know that It is not difficult to conceive an effective system.

Fernando Branco considers that this is “The greatest perplexity of the tragedy”.

“This is a Severe conception failure No one has realized that the braking system After all I had no ability to hold on to the lift If the cable came. I shock me a lot, ”laments the expert.

Another possible explanations to contribute to the September 3 disaster is the existence of excess oil that may have affected one of the brake systems.

Pedro Amaral says that the noise that is heard in the videos of the day of the accident reveals that the “Brake system was not being effective”.

“There is oil is a hypothesis that would reduce the braking capacity against the gutter walls.” Admits Fernando Branco. However, “The report does not refer to this aspect”underlines.