Liseberg in Gothenburg is Sweden’s largest amusement park. The Helix roller coaster is one of the attractions that swirls up an adrenalin kick. With a 1380m track, Helix is the longest looping roller coaster in Europe and the second longest in the world. It hurls its riders at up to 90km/h through six loops and exposes them to up to five times their own bodyweight. This is the first time anywhere in the world where half of the riders (Helix takes up to 28) sit facing backwards, making the ride even more exciting.
Before the start, the riders have to be brought to the start ramp at a height of 41m. Controlled asynchronous drives with 315kW of power are used to move the carriages into the start position. The speed of this drive is recorded by the original Hübner Berlin POG 10 HeavyDuty encoder from Baumer. No easy task, as the roller coaster is freely exposed to the elements, including heat from the sun, moisture from rain or wind currents. Hence the decision for HeavyDuty encoders from Baumer, making sure the riders experience the thrill as a pleasure too.
The POG 10 incremental HeavyDuty encoder and its sister model, the HOG 10 with hollow shaft, are among the most versatile product ranges of the Baumer HeavyDuty encoders. They deliver reliable speed data in a host of potential applications and operate under the toughest conditions. As a result, they help prevent failures and maintain the availability of machines and systems. This saves downtime costs in a host of applications. With the roller coaster, it even makes a valuable contribution to the safety of human life – a malfunction in the drive of a carriage would at best be annoying for the riders, and at worst a life-threatening experience.
The HeavyDuty technology of the POG 10 guarantees high reliability under challenging environmental conditions through numerous specific features. Thanks to solid and generously dimensioned wall thicknesses and a warp-resistant design, the die-cast housings are extremely robust and highly resistant to vibration and shock. Bearings at both encoder shaft ends and the metallic incremental disk offer huge power reserves and unparalleled durability through extreme resilience to axial and radial forces.
For outdoor use the excellent anticorrosive properties of the CX category of HeavyDuty encoders to EN ISO 12944, achieved through an optimal choice of material and high-resistant coating, are also extremely important. These properties allow the encoders to be used even on or in the ocean, in the Arctic, in the tropics or in the desert.
The combination of labyrinth and shaft seals also protects the inner workings of the HeavyDuty encoders from solid, moist and paste-like contamination. This sealing concept conforms to protection classes IP 66 and IP 67 within a broad temperature range of up to 95°C. Current-insulated bearings ultimately protect the ball bearings of the encoder from current flashovers, and this averts any impairment of the lubricant effect.
The result is an almost indestructible full package that effectively prevents potential malfunctions and failures, even during tough continuous use in a roller coaster. This is all the more important as a replacement can get very costly – not because the encoder itself is expensive, but because it is typically mounted in barely accessible locations, as is the case on a roller coaster.
HeavyDuty means highly resilient. This is not only about a tight, solid housing and protection against the elements. The intrinsic values have to be right as well. “Of course, it’s always the strong ones, so to speak, that are used when the going gets tough,” explains Steffen Günther, head of the HeavyDuty business unit at Baumer. “Yet HeavyDuty offers an all-encompassing performance promise: such encoders must, first and foremost, function under extreme conditions at all times. Secondly, however, their signal accuracy must not suffer under these adverse conditions. For an encoder to be called HeavyDuty, it must be absolutely durable, impermeable and precise.”
Reliable precision is ensured by the interference-immune scanning function with highly robust, optical circuits (Opto-ASIC). This guarantees optimum electromagnetic compatibility with a burst strength for high-voltage pulses of up to 4kV. In addition, the Enhanced Monitoring System (EMS) continuously checks numerous encoder functions, swiftly detects connection and encoder errors and transmits the encoder status to the inverter or to the control via an error output.
The HeavyDuty encoders achieve the best possible SinCos signal quality through the LowHarmonics technology for outstanding control quality, low drive heat-up and high energy efficiency. The incremental square signal outputs also have short-circuit proof, powerful transistor drivers for peak currents of up to 300mA. They ensure reliable signal quality even over long-distance transmissions of up to 350m.
These features – resilience and precision – make an important contribution to ensuring that the Gothenburg roller coaster riders are brought to the start ramp safely and at the correct speed. A good thing too, since this ascent to 41m is thrilling enough without any failures. It can be assumed that the riders on the roller coaster in the Liseberg amusement park have no idea what's going on. This promise of resilience and precision, however, keeps the operators safe in the knowledge that their ride will never become a roller coaster of feelings for them.