The major difference between traction and hydraulic elevators is in the way the systems transport the cab. With Traction elevator, the cab is raised and lowered by traction steel ropes or belts on a pulley system. Compared to hydraulic systems, traction elevators:
Uses less energy
Serve mid to high-rise buildings
Ride smoother
Traction elevators use a counterweight to offset the weight of the cab and occupants. With this design, the motor doesn’t have to move as much weight, making it much more energy efficient than hydraulic systems.
Traction elevators are the most common type of elevator. They can be geared or gearless and both model types are driven by alternating current (AC) or direct current (DC) electrical motors.
Geared Elevators
In geared elevators, there is a gearbox attached to the motor that drives the wheel and moves the ropes. Geared machines can reach speeds up to 500 ft./min. These models will have a middle-of-the-road cost in terms of initial investment, maintenance costs and energy consumption.
Gearless Elevators
In gearless traction elevators, the sheave is attached directly to the end of the motor. These models can reach speeds up to 2,000 ft./min. These models have a high initial cost investment and average maintenance costs. They are, however, more energy efficient than geared traction elevators.
PROS & CONS OF Traction Elevators
Self-Supported MRL (Most Common Traction Elevator)
Pros:
Net travel above 60’
Smaller control room requirements
Smaller motor size
Possibly a quieter ride
Cons:
More expensive to install and maintain
Crane is typically required (building roof cannot be installed over hoistway)
Limited on cab weights
Limited on cab capacities
Increased overhead/pit requirements
4-6 weeks added to project schedule
コメント