Wednesday, 26 February 2020
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Hydraulic lifts: In the lead in endurance test

When New Lift predicted the comeback of hydraulic lifts, few people took the control manufacturer seriously. But now it is clear that modernising tried-and-tested technology has many advantages.

(Photo: © New Lift)

There’s life in the old dog yet. The number of LPs sold since 2007 has increased tenfold. The hydraulic lift is currently experiencing a similar comeback.

Its weaknesses were no secret. Intensive research and development have resulted in many innovations and improvements, such as conversion to frequency control.

OK thanks to R&D

In order to be able to continue to use the existing hydraulic unit, New Lift’s engineers together with the frequency converter specialists of Ziehl-Abegg developed the MOD-HY modernisation package.

This not only avoids expensive replacement of the drive unit, but also makes sensors, encoders and additional interfaces at the valve block superfluous. Consequently, the costs are moderate – the investment is amortised within a short period.

The cost argument

The two lifts in the Aurelius-Hof, an old age home in the German federal state of Hessen, were causing problems. The oil was getting hot from the intensive use. The oil coolers ran round the clock and the waste heat was discharged into the building through the open machine room doors. Consequently, solving the oil problem was a priority when it was time for modernisation in 2015. At the same time, minimising the costs and duration of the conversion was desired, which was why the MOD-HY package was chosen.

HandwerkAfter four years of trouble-free operation, the energy meter revealed that over 60 percent savings had been made in electricity. Instead of 32,000 kWh of energy, only 12,997 kWh were needed. At a kWh price of 28 cents, this corresponds to savings of over 5,000 euros.

Consequently, the modern converter technology amortised itself early. Preservation of the drive unit also meant the conversion was completed quickly, with a minimal downtime. The maintenance effort is manageable, thanks to the reliable, sophisticated hydraulic technology.

Practical test passed

An old age home is very demanding in terms of comfort and the control of odours and noise. "Here too, the MOD-HY modernisation package sets standards," emphasised New Lift. The modernised lift does its work quietly in the face of increased conveyance performance (thanks to the elimination of creep speed with DCP04). There are also no odours without the oil overheating. The halting precision – vital for older people – is exemplary.

This overall package of energy efficiency, travel comfort, reliability and fast amortisation is allowing the hydraulic lift its comeback The demand for MOD-HY is increasing, according to the company from Kell am See (Germany), "The prophecies of doom have fallen silent. No-one's talking about the end of vinyl discs anymore either."

This is what you get with the MOD-HY modernisation package:
- Much lower energy consumption
- Less noise, no odours
- More travel comfort
- Greater conveyance performance

This is how it works:
Fig. 1 illustrates the technical processes: the upward trip now occurs frequency-controlled and unprotected with ZAdyn4CA HY from Ziehl Abegg –and as a result saves energy. The downward trip continues to be electromechanical. The FST-2XT controller has a specially-developed pseudo-closed loop procedure with DCP04 and absolute encoder shaft copying.

The DCP04 interface between FST-2T and ZAdyn4CA HY permits direct entry of the landing without creep approach, step formation and brake resistance. This guarantees optimal travel comfort.

The environmental balance sheet is also as it should be. During the upward trip, excess oil is no longer pumped via the bypass valve back into the tank. The hydraulic pump is now only regulated by frequency to the engine speed required for the speed required. In addition, this prevents oil heating.

Power-greedy oil-cooling systems are superfluous. Only half the pump electricity is now needed during acceleration and deceleration. Consequently the modernised hydraulic lift is far more energy-efficient. The noise produced by the motor contactor has also been eliminated.

In addition, oil viscosity no longer affects the speed. The ZAdyn4CA HY software uses a fine-tuning function during start-up to determine the difference between static- and sliding friction and the offset speed required for correction when starting and stopping. Elaborate adjustments are no longer required.

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