What are the pros and cons between a machine-room-less (MRL) type elevator and the traditional elevator systems? This is a question we are asked quite often.
A little history
Elevator technology has been in existence long before electricity. The first reference to an elevator is in the works of the Roman architect, who built his first elevator probably in 236 BC. In some literary sources of later historical periods, elevators were mentioned as cabs on a hemp rope and powered by hand or by animals. It is supposed that elevators of this type were installed in the Sinai Monastery of Egypt. It wasn’t until 1852 when Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. The design of the Otis safety elevator is somewhat similar to one type still used today. A governor device engages knurled roller(s); locking the elevator to its guides should the elevator descend at excessive speed. He demonstrated it at the New York exposition in the Crystal Palace in a dramatic, death-defying presentation in 1854.
Today, we have 5 different choices when it comes to the type of driving machine and technology behind elevators.
The oldest technology, the winding drum cable, is similar to the old Roman style. A motor drives a rotating drum that winds and unwinds a cable to lift/lower the elevator.
It wasn’t until 1846 when the first water hydraulic elevators were invented. Now the technology has not only evolved to plant based oil, but the in-ground design is seldom used as the technology of hole-less hydraulics and roped hydraulic systems. The roped hydraulic elevator is very popular in residential applications.
The first traction type electric elevator was built by Werner von Siemens in 1880 in Germany. In 1999, the adaptation of this type of elevator technology gave birth to the MRL design. Another adaptation of this is the chain driven type MRL elevator.
In 2000 a vacuum elevator was offered commercially in Argentina.
So, with all of these choices, the question remains, which is the best technology?
Any of the technologies will rate differently from each other when it comes to power consumption. Smooth and quiet ride is another difference that can be measured between the different technologies. The only thing all of the technologies have in common is they all provide an effortless solution to travel vertically between floors of a building.
An important and often overlooked important factor to be considered is how easily the components that control the elevator are to access in the event of failure and ease of servicing.
So let’s discuss the newer MRL technology as compared to the other systems. One extremely important factor is until recently, the national and local building codes did not address elevators without machine rooms. Residential MRL Elevators are still not allowed by the ASME A17 code in the US. MRL elevators have been recognized in the 2005 supplement to the 2004 A17.1 Elevator Code. The controller cabinet is required to be located outside the hoistway space and in a dedicated area. There is a reason behind this as having an elevator “machine” that is not in a “room” makes it very difficult and dangerous to access in the event of malfunction or service.
Let’s now discuss the “room” required for the elevator “machine”. In commercial applications, the use of higher voltage and required dedicated machine room leaves the fact that at least 25 sq. ft. valuable space is needed for the elevator equipment. With overhead machinery and traction elevators (and in some cases even hydraulic) the machine room can simply be located above the elevator hoistway as long as there is proper access to it and enough room for it. In the case of hydraulic elevators, the machine room (or equipment space) can be remotely located as far away as the manufacture of the equipment will allow, sometimes on another floor or other side of the building.
In the case of most residential applications, a dedicated machine room is not required so the elevator equipment can be in the same space as other mechanical equipment such as a furnace or water heater or other mechanical room. In any case, there are electrical and clearance codes that need to be considered in the planning and layout.
Elevator technology is constantly being developed and redesigned. One would ask how long a new technology should be in the market before it is deemed “reliable”.
In conclusion, what is better? Having a quiet, smooth ride with in-accessible machinery or the same smooth and in some cases an even quieter ride with accessible machinery? Think of an automobile in the future being designed “hood-less”.