Years of expertise in drive technology
Over the years, our employees have acquired a wealth of expertise, which they can skillfully apply to meet your requirements.
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Unique location
With our unique assembly and repair plant, we can carry out repairs and assemblies at any time and send them to you within 24 hours.
Inclined elevators are suitable for sloping terrain and ensure safe and comfortable transport for people, luggage, and goods. Whether as a feeder for a cable car in La Paz or as a means of transport to the Hotel Château Gütsch in Lucerne: in order to offer consistently high product quality, manufacturers rely on drive technology from SEW-EURODRIVE, which is supplied by the Swiss general agency Alfred Imhof AG.
To counteract the steady increase in traffic, more and more cities are turning to cable cars as a means of public transport. This is also the case in the Bolivian capital of La Paz. In 2014, Doppelmayr put the first cable cars into operation in the metropolis, located at 3,750 meters above sea level, connecting La Paz with its neighbor city El Alto, which is located at a higher altitude. The cable car specialist Inauen-Schätti AG from Schwanden is also involved in the project and supplied an inclined elevator that serves as a feeder from the bus terminal to the cable car station.
The 90 kW drive for the inclined elevator, a combination of an SEW bevel gear unit and an AKH motor, was delivered by Alfred Imhof AG in September 2014. The inclined elevator officially went into operation in February 2015. A few months later, however, vibrations were detected, which meant that the speed of the drive had to be reduced. A vibration analysis specialist called in from Spain was able to confirm the vibrations with technical measurements, but was unable to find the causes. Inauen-Schätti therefore decided to contact Alfred Imhof AG, and shortly afterwards Rainer Trumpp, project manager and specialist for expert reports at Alfred Imhof AG, set off for La Paz together with an employee from Inauen-Schätti. The aim of the trip was to determine the exact cause of the vibrations and to draw up a catalog of measures.
| Total length of route | 33 km |
| Capacity per Line | 1 million passengers/month |
| Inclined elevator | |
| Track length | 74m |
| Cabin size | 20 people / 1'600kg |
| Number of stations | 2 |
| Travel speed | 2 m/s |
| Motor power | 90 kW |
| Height difference | 26 m |
| Year of construction | 2015 |
"The altitude in the Bolivian capital was a real problem at first, as we had hardly any time to acclimatize. The lower oxygen made every (work) step exhausting. But over time, you get used to the difficult working conditions," says Rainer Trumpp. In order to get to the bottom of the causes of the vibrations, measurements had to be taken at various points on the drive and on the entire structure, both under load, during normal operation, and during empty runs. However, during the previous rope inspection, it was found that the rope roller guides were severely cut on one side. The initial suspicion that the wear was related to varying rope tension was not confirmed. Rather, the high mechanical abrasion was caused by abrasive wear brought about by a combination of oil, dust, soot, and exhaust gases adhering to the rope. In order to restore the normal resonance of the system, the rollers were replaced first. Subsequent vibration measurements revealed very strong radial and axial vibrations, some of which originated from the overall drive and some of which were due to the design.
An examination of the drive revealed wear marks on the spherical roller bearing and corrosion marks on the handwheel and motor shaft. The handwheel, which was loose on the shaft, exhibited a lateral runout of several millimeters. The imbalance caused the key connection to expand so much the shaft and handwheel rubbed against each other. This caused strong vibrations and the entire drive. A locking screw reduced the vibrations.
Various measurements on the inclined elevator revealed axial vibrations that could be subjectively perceived as disturbing by passengers in the cabin. Rainer Trumpp: “The cause here was the substructure. One of the support pillars was mounted on the concrete base using a welded construction, and the wire ropes attached for stabilization had considerable play.”
By eliminating the identified causes, the vibrations in the entire system were ultimately reduced significantly. “With the additional measures that we recommended to the client in a detailed expert report, the remaining vibrations can be reduced to a minimum, guaranteeing optimal availability of the inclined elevator.”
With the steadily growing cable car network in La Paz, hundreds of thousands of people are benefiting from the improved quality of life month after month. Watch the film on our homepage to see how the new mode of transport is making everyday life easier for the local population.