Lerch Bates Inc. Building Insight

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MRL elevators

MRL

Say it. M – R – L.  Learn it. Know it.  Believe it.  Embrace it.

MRL is the accepted industry acronym for the latest, most widespread innovation in elevator technology.  MRL is short for Machine Room Less.  The innovative feature that makes the MRL possible is a compact, energy efficient, permanent magnet synchronous motor (PMSM) gearless machine.  Gearless has traditionally referred to those monstrous, expensive, high speed machines that move elevators in high rise buildings from 500 to 2000 fpm.  But these new machines are much more compact, more energy efficient, much smaller, and as a result, can be installed within the elevator hoistway, eliminating the need for an overhead machine room.

The MRL has replaced the traditional geared machine type traction elevator that has dominated the mid rise elevator market, from 5-15 floors, for over 50 years and provides elevators at speeds of 200-500 fpm.  The MRL is also making a significant dent in the market for higher rise hydraulic elevators.  Where it was previously not unusual to see hydraulic elevators used in 5 or 6, even 7 stop applications where there was low to moderate use, the MRL now dominates.  The high costs of drilling for hydraulic jacks as well as the large motor size and high energy demands of hydraulic elevators make the MRL an attractive alternative.  The MRL is much more energy efficient and provides superior ride quality and overall performance than hydraulic elevators.

Do not be deceived, however, into thinking that there are no equipment room requirements.  Here in the US, elevator codes continue to require a separate fire rated enclosure, basically an electrical closet, to house the elevator controller.  The good thing is, this room can be located remotely from the elevator, up to 150 or more, depending on the manufacturer.  In European applications, the codes actually allow the control equipment to be located within the elevator hoistway, making the euro version a true Machine Room Less elevator.

But to call it “new” is a bit of a misnomer.  The use of MRLs has been growing steadily in US markets over the past 10 years, but has been a staple of European elevator markets for much longer.  The long and arduous process of revising US codes and meeting US size standards (SUPERSIZED) have slowed the introduction of the MRL in US markets.

All of the major elevator manufacturing companies now have an MRL product available in virtually all US markets.  Because the US product is relatively young, it continues to change.  Each company has come up with its own MRL solution, and has responded to the competition by modifying their designs to be competitive.

One of the difficulties in applying MRLs to the US market is the vast differences between the different manufacturers.  Otis has aptly named their MRL the GEN2, indicating the 2nd generation of elevators.  Whereas, in the past, an elevator was an elevator, the MRL has changed all that.  Traditional gearless, geared and hydraulic elevators have nearly the same structural, electrical and architectural requirements, regardless of the manufacturer. It was easy to design a building with elevator hoistways and machine rooms that can accommodate the products of multiple manufacturers, making it a very competitive marketplace and giving buyers plenty of options.  But now, because of this drastic change in elevator design (2nd generation,) and because each manufacturer has its own MRL solution, there are potentially significant differences between the products of different companies.  This makes the task of architects and consultants a bit more difficult and can limit competition and result in higher costs.

But make no mistake, the MRL is here to stay.  Every day there are more and more manufacturers of components that can be assembled into an MRL, and several manufacturers now offer a complete MRL package to independent elevator companies that can compete with the big boys.  And as this technology continues to evolve, the differences between the various manufacturers will continue to disappear, and more non-standard applications are becoming possible.  This is good news for designers and consultants, and more importantly, for buyers, who increasingly have options that offer the many advantages of the MRL.

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