Game, set and match for hydraulic elevators
 Glasaufzug

written by Michael Pyper on Friday, August 20, 2021

Traction elevators versus hydraulic elevators - it's about speed, acceleration, accuracy and consistency. Many aspects speak in favor of hydraulics.

It is certainly true that hydraulic elevators are not always and everywhere the better choice. To equip a high-rise with hydraulic elevators would be technically daring and economically inefficient. However, in buildings with up to five floors, - and this applies to apartment and industrial buildings with high-payload elevators - the hydraulic elevator is at least equal to its traction competitor. In cost comparisons, the high maintenance and spare parts costs for traction elevators are often overlooked.

An example: the electric motor-driven traction sheave and the ropes are subject to high fretting, and replacing them is time-consuming and expensive. Although hydraulic elevators also use ropes for greater travel distances, the ropes only run over guide pulleys, where hardly any wear occurs. The hydraulic oil only needs to be checked every three to five years. It can often be treated by filtering on site and then reused. Before making an investment decision, the total costs of ownership should therefore always be compared.

 

Fast installation, safe in operation, rapair and maintenance

Hydraulic elevators feature simple and cost-effective installation compared with traction elevators. This is why they are also particularly suitable for projects where retrofitting is involved. All the technology can be placed at ground level and away from the elevator shaft. The heavy drive system of a traction elevator, however, is usually situated in the shaft head or even above the shaft and is harder to reach. This makes assembly work more dangerous.

Keyword safety: even during service and repair work the hydraulic elevator is safer as there are no moving counterweights or drive components in the shaft head that could fall into the depths. This is a major advantage for hydraulics, especially in earthquake-prone areas. Last but not least, the emergency evacuation procedures are much simpler and safer. It is sufficient to open a valve and the elevator car then moves down in a controlled manner without any power supply.

Comfortable and simply beautiful

Hydraulic elevators are distinguished by their outstanding travel characteristics. Due to legal regulations they are not allowed to travel faster than one meter per second, but once again we see that speed isn't everything. Thanks to the self-optimizing travel curve of Bucher Hydraulics' elevator components, they easily make up for lost time when starting and when approaching the landings - which they do with unique precision, by the way. There are no pitfalls here.

 Elevator without trip hazards

An important aspect for apartment buildings: hydraulic elevators have low-noise levels because the power unit can be situated in the machine room, with suitable sound insulation. In addition, the shaft floor area can be fully utilized because the counterweight is no longer required and the car floor area can be made correspondingly larger.

Design-oriented architects are convinced by another factor: a slim and shiny cylinder below the car looks delicate and aesthetic. Modern designs even work without any lateral car guidance at all, which, for example, allows the construction of round glass cars without guide rails. This allows elevator doors to be installed in any direction. The hydraulic power unit and other equipment fit in a wall cabinet or in the shaft below the car.

 Design flexibility

The advantages of hydraulics elevators

  • Outstanding design opportunities and small space requirement offer very wide creative scope to architects
  • A high level of safety due to simple and reliable emergency controls, safe use in earthquake zones as well as low-maintenance and repair
  • Low-maintenance drive technology, as there is no wear on pulleys and ropes; low demand for replacement parts; drive is easy accessible - all that with free choice of maintenance companies
  • Simple and economical assembly - also suitable for retrofitting
  • High cost-effectiveness for apartment and industrial buildings with up to five floors
  • Low noise level within the building as the hydraulic drive can be placed in the machine room far away from the shaft

Three Questions for Tony Aschwanden, Head of Product & Application - Elevator

Mr. Aschwanden, some people keep saying that hydraulic elevators consume significantly more energy than traction elevators. Is that still the case today? 

Definitely not! In many infrequently used elevator installations, the standby power consumption of the frequency-controlled traction elevator systems can exceed the travel energy. In such cases a conventional hydraulic power unit with low standby power consumption makes more sense. It is even the case that studies of elevator installations in apartment buildings confirm better energy efficiency in hydraulic elevators than in traction elevators. Depending on the application, however, a hydraulic drive with frequency control can be installed even where a high number of travels is required. In addition, there are further opportunities for energy reduction with options such as power regeneration or SuperCaps. Of course, these options mean extra money and the acquisition costs are correspondingly higher, but in the long run the higher efficiency pays off for the operator.

A strong point of the hydraulic elevator is the flexible positioning of the drive. Why does it play such a big role? 

For one thing, elevators have to be acoustically isolated from the apartments. This is usually achieved by running the staircase around the elevator shaft, but this clearly restricts the architect's options. On the other hand, with the traction elevator the noisy drive, with motor, gear box and traction sheave, is placed at the top of the shaft head and so is close to the apartments, including penthouse, that are particularly well marketed. With the hydraulic elevator, however, the machine room can be ideally positioned at some distance from noise-sensitive rooms such as bedrooms and living rooms.

Other typical objections are the danger to the environment from the hydraulic oil and a possible odor nuisance. Are these justified? 

Both of these are absolutely manageable if the system is designed correctly. Escaping oil - which happens extremely rarely - can be collected in the shaft, the bottom of which can be provided with an appropriate protective layer. Slight odors may arise if the oil heats up after a high number of travels. But this heating does not occur when the system is designed correctly or when a frequency inverter is used, as in this latter case no excess oil has to flow through the valve. So it's one to nothing for hydraulics, if used correctly.

Find out more

Product Page: Elevator Hydraulics

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