Machine Room Less Elevators
Most machine room less elevators are used for low to mid rise buildings. Machine room less elevators in mid-rise buildings usually serves up to 20 floors. There is a very rare design in which the traction machine is positioned under the elevator cab.
Machine room less elevators do not have a fixed machine room on the top of the hoistway, instead the traction hoisting machine is installed either on the top side wall of the hoistway or on the bottom of the hoistway. The motor is installed using a permanent magnet which "sticks" the motor permanently and work with Variable Voltage Variable Frequency (VVVF) drive. Some of the hoisting machines are using gearless synchronous motors instead conventional induction motors. This design eliminates the need of a fixed machine room and thus saves much building's space. Almost all the traction MRL elevators are gearless traction