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Types of Traction elevators
Hole type elevators
Rope type elevator
Without machine room elevator
Hydraulic elevator
Without machine room elevator
Traction elevators operate using steel cables or ropes passing over a sheave connected to an electric motor. The MRL (Machine Room-Less) elevator is a modern type of traction elevator where the compact motor and controller are located within the hoistway itself, eliminating the need for a separate machine room.
Traction elevators operate using steel cables or ropes passing over a sheave connected to an electric motor. The MRL (Machine Room-Less) elevator is a modern type of traction elevator where the compact motor and controller are located within the hoistway itself, eliminating the need for a separate machine room.
TmotorтАЛ=(WcarтАЛтИТWcounterтАЛ)├ЧRsheaveтАЛ тАФ basic torque balance for traction drive
P=╬╖F├ЧvтАЛ тАФ power requirement for the traction drive system
The traction system relies on friction between the hoist ropes and the driving sheave. The counterweight provides balance to the elevator car, significantly reducing the torque required by the motor. In MRL systems, permanent magnet synchronous motors (PMSM) are used due to their slim profile, allowing them to fit into the restricted space of the elevator shaft.
Traction elevators use high-friction steel ropes over a motorized sheave.
MRL elevators are highly energy-efficient due to gearless PM synchronous machines.
The counterweight reduces the effective load on the driving motor.
Hydraulic elevators are categorized separately from traction elevators.
Space-saving (no dedicated machine room required)
Higher energy efficiency
Smoother ride and quieter operation
Maintenance in the hoistway can be restricted
High installation precision required
Mid-rise residential buildings
Commercial offices
Buildings with space constraints
| Feature | Traction Elevator | Hydraulic Elevator |
|---|---|---|
Driving Mechanism | Friction/Rope | Fluid Pressure |
Hole type elevators are a variant of hydraulic elevators (usually requiring a deep hole for the plunger).
Rope type is a broad category, and MRL is a subset of traction technology.
Option D (Hydraulic) is a completely different operating principle from traction.
C is correct тАФ The Machine Room-Less (MRL) elevator is a modern design of a traction elevator where all mechanical equipment fits within the elevator shaft.
In competitive exams, always distinguish between 'Traction' (rope-based) and 'Hydraulic' (piston/fluid-based) systems, as they represent the two primary categories of vertical transport.