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Welcome to Classroom on demand, your source for educational materials related to the vertical transportation industry. This site represents the knowledge and expertise of the best engineers and mechanics in the elevator industry, and will help those new to the elevator industry learn about the basic workings of elevator systems, and also will serve as a reference for people with more experience.

Traction Machine Room-Less (MRL)

The Machine Room-Less (MRL) elevator is now available because advanced motor technology has reduced the size of electric motors used with traction equipment. These newly designed permanent magnet motors (PMM) allow the manufacturers to locate the machines in the hoistway overhead, thus eliminating the need for a machine room, typically over the hoistway. A typical traction elevator requires a sheave-to-rope ratio of 40:1 – in other words, a sheave 40 times the diameter of the hoist rope. Smaller ratios such as 16:1 might be achieved with the MRL hoisting methods. When these types of smaller ratios are achieved, a flexible high strength hoist rope is used to provide the smaller 16:1 ratio. The grooves are shaped to grip the hoist ropes.
The smaller rope ratio means a much smaller drive sheave, and a smaller, more energy-efficient gearless machine to operate it. This smaller drive motor can be installed in the hoistway overhead and does not require a machine room. The typical traction elevator machine requires about, on average, 120 sq feet for the machine. So eliminating the machine room can save an average of 120 square feet per elevator.
The MRL application utilizes a drive sheave, motor, counterweight, and ropes which are the same components used by the geared and gearless traction elevator. The TKE MRL design uses a gearless machine. Other MRL manufactures may use geared equipment; however, gearless machines are the more popular choice amongst mainstream elevator companies.
This application can be used for front openings as well as front and rear opening configurations.
The electric motor interfaces directly with the drive sheave. MRL incorporates the latest elevator drive technology using a gearless synchronous cylindrical machine. "Gearless" means there is no gear box as the motor interfaces directly with the drive sheave.
The ThyssenKrupp Elevator MRL gearless machine, along with the related drive equipment, is located above the hoistway in the overhead and NOT in a dedicated machine room.
ThyssenKrupp Elevator MRL gearless machine speeds are currently 200 to 350 fpm (1.02 to 1.78 m/sec). Travel distance is currently at 300 feet maximum distance. Ongoing engineering is expected to allow MRL elevators to reach higher speeds and larger maximum travels in the near future.
Although the MRL gearless machine and governor are located in the overhead of the hoistway, depending on local code requirements, the TKE controller is located in a control room. The control room is located adjacent to the hoistway, typically at the first landing. The room must be code compliant to provide correct electrical and working clearances.

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