The elevating operator’s cab for tower cranes, Procab, has now concluded its first real-life site test outside of Sweden and been hailed a great benefit.
The Procab, a cabin which can be moved up and down the tower of the crane to the position of optimum visibility, was developed by Swedish company Prokrania in 1992.
To date, it has only been used on a few projects in that country and has proved hard to export. Not many countries have a culture in which contractors are prepared to fund safety initiatives that go beyond compulsory standards.
However, in a French government-aided pilot project, the Procab has now been used by contractor GFC, a subsidiary of Bouygues, on a 65m-high Potain MD265 on the construction of the Pont-Salomon viaduct near Lyon. It was on site from September 1999 until the start of this month.
Nearly half the funding for the Procab trial came from government safety authorities. The presence of four other cranes on site made it possible to compare the Procab with traditional operating conditions.
The project was overseen by Prokrania’s agent in France, SMIE. Jean-Louis Olivier, president and director general of SMIE, admitted to early teething problems with the settings but said there were no operational problems. “The crane driver was very happy,” Olivier said. “He wants to follow the cab now.”
Normally, the Procab cabin would replace the standard manufacturer’s cabin on the crane. But on the Pont Salomon project the original Potain cab was kept at the top of the crane in case of problems.
The elevating cabin now moves onto the construction high-rise building, also in the Lyon region, to assess productivity benefits on a different type of project. Olivier said that he expected the Procab to be of greater benefit on this site as being able to move the viewing position of the cab as the building progresses would be more of an asset.
What is the procab?
The Procab is a combined elevator and operator’s cabin which is synchronised with the slewing movement of the crane. It was developed in 1992 by Prokrania in Sweden where , by law, all tower cranes which have a height under hook of more than 25m must be fitted with an elevator for the operator. The crane operator can select the appropriate height to get the best view of the construction site below.
How does it work?
It consist of a frame running along the corners of the mast on plastic wheels, around which the platform which supports the cabin can rotate. The frame is suspended from two cables attached to a winch at the top of the tower. Slewing motion of the cabin is controlled by an electronic device, using a proximity detector that detects relative motion of the support cables as the jib slews. A motor is then activated to slew the cabin.
is it any good?
Claimed benefits include:
optimised operating height gives best view for the driver and so offers a more ergonomic operating position
it also improves operational accuracy and communications between operator and banksman
it removes cardiac stress induced by operators having to climb up high cranes
it improves efficiency as the availability of both operator and crane is maximised.
