In the mid-1920s, Jakob Wyssen bought some land in the mountains near his home in Reichenbach, Switzerland, about a 2hr drive from Zurich. The land came with a lot of timber; and like most of his contemporaries at that time, the only way he could get the timber down the mountain to his sawmill was manually, which was arduous and labour-intensive.
In 1928, Mr Wyssen invented the skyline crane. This was a simple overhead cable (running from the top of the mountain to the bottom), from which he suspended a wheeled carriage equipped with a load carrier. The carriage was dragged to the top of the mountain, where a hook could be let down for attaching to the load, which would then travel back down the cable by gravity. It was a simple but effective labour-saving invention that quickly caught the attention of mountain woodsmen far and wide.
In 1940, Mr Wyssen mothballed his sawmill and started Wyssen Skyline Cranes; in 1944, he developed a semi-automatic carriage. Some 10 years later, he began making an automated version with which the carriage could clamp itself to the cable at any point. The hook would then be lowered, the load winched up and the carriage moved either up or down the cable.
The company Mr Wyssen founded is still owned by his family. It is run by his grandsons Jürg, Jakob and Christian; a cousin, Sam, also works with the brothers. Today, Wyssen Seilbahnen AG has 36 employees (four of whom are apprentices) and two divisions, which produce skyline cranes and avalanche control systems. The former are built and shipped to customers all over the world — mostly governments or private enterprises managing timber and forestry.
Jürg Wyssen, head of engineering, says: “Skyline cranes are very environment-friendly. There’s no need to build or widen roads to get timber down the mountain. The towers have a very small footprint, and the load — the timber — travels above the terrain and any obstacles.”
Meanwhile, the Wyssen avalanche control system contributes a growing percentage of the company’s revenues. It uses large steel towers that are stationed permanently on avalanche-prone mountainsides. At the top of each tower is a circular container, inside which is a cluster of dynamite charges that can be activated remotely to precipitate an avalanche. When the operator presses the button, a 5kg charge drops down on a wire to just above the snow level, where it detonates. The shock wave dissipates across the snow face and causes an avalanche, without damaging the underlying rock.
“Avalanche control blasts are traditionally undertaken from helicopters or by hand, on the ground,” says Jürg Wyssen. “The former method is expensive, while the latter is dangerous. The Wyssen system doesn’t require good weather, so the avalanche can be triggered at the most opportune moment after a heavy snow fall — usually before skiers, hikers or climbers return to the area.”
As well as its use in timber and forestry, the skyline crane is also used on construction projects, including hydroelectric power plants, large-span bridges and suspension bridges. Wyssen Seilbahnen makes and delivers whole skyline crane systems, including the carriage, cable, towers, and winches.
Machine tool purchases
Jürg Wyssen says: “We keep almost all parts in stock, even for machines built up to 60 years ago. Gears are sub-contracted, as are some of the specialist finishes, such as anodising. Grinding, nickel plating, hardening, chroming are also done outside, but each finished Wyssen skyline crane contains around 1,000 parts, so there’s no shortage of work for our predominantly Haas machines.”
Wyssen Seilbahnen bought its first Haas CNC machine tool
(www.haascnc.com) — a VF-4 vertical machining centre — about seven years ago. A year later, it bought a Super Mini-Mill and a TM-1 Toolroom Mill. A year after that, it bought an SL-20 CNC turning centre and another Super MiniMill. Since then, the company has continually invested in Haas machines.
“All Wyssen parts are designed in SolidWorks. The programmes are created using Esprit CAM and downloaded straight to the machines. A typical part batch is 30-off, so quick set-up is a priority. We also aim to machine as many parts as possible ‘in one hit’. The Haas plug-and-play rotary table and fourth-axis system was another reason we decided to invest in Haas. Meanwhile, the Haas TL-25 has a full C axis, live tooling and a sub-spindle, so we can machine the back ends of components; this removes the need for them to be moved to one of the vertical machines for second or third ops.”
For some parts, switching between machines is unavoidable. Batches of 50-off of a heavy steel component about 30cm long are turned on the SL-20 or the TL-25, before a cross-hole in each is machined on the VF-4. The final operation is machining a groove, which is also undertaken on the TL-25. “The most difficult and technically demanding part we make on the Haas machines is the choker,” says Jürg Wyssen. “This has challenging geometries and tight tolerances and is made from high-strength steel. It’s milled on the VF-4 in two set-ups and requires use of the fourth axis.”
Haas machines are distributed and supported in Switzerland by the Haas Factory Outlet (HFO) owned and operated by URMA AG, a well-known manufacturer of metal-cutting tools and tool-holders. Jürg Wyssen and his brothers first saw Haas machines at the Prodex show in Basel. “The head of our machine shop at the time was set on buying another make of machine tool, also from the USA. However, when we were ready to buy, I contacted URMA about the machines I’d seen in Basel and discovered that a Haas with the same ‘spec’ as the machine our shop manager wanted would cost half as much! Furthermore, because all our Haas machines use similar controls, we need very few people to operate them. This is a distinct advantage for us, as it is difficult to find machine operators in this area.”