Geared vs. Gearless Traction Elevators

Traction elevators are one of the most commonly used types of elevators. They use a rope and pulley system to raise and lower the elevator cab. The weight of their cab is balanced by using a counterweight, which was first introduced in 1900. Nowadays, some elevators are using steel belts in place of steel ropes. These steel belts are flat and extremely light because of the high friction coating, and carbon fibre core. Also, these belts do not require oil or lubricant. All these qualities make traction elevators energy efficient and best suited for high-rise applications. There are three main types of traction elevators:
  • Geared Traction Elevators
  • Gearless Traction Elevators
  • Machine Room-Less Traction Elevators
    • Geared Traction Elevators

      These traction elevators have a gearbox which is attached to the electric motor and turns the hoist sheave and moves the rope. Geared traction elevators are driven by either direct current (DC) or alternating current (AC) and their maximum speed is up to 500 ft. per minute. This speed limit is lower than gearless traction elevators but higher than many other types of elevators. Moreover, these elevators are capable of traveling to a maximum distance of 250 ft. Geared traction elevators have fair installation and maintenance costs, and low energy consumption. While their speed is slower than gearless elevators, geared elevators offer advantages in terms of energy efficiency as they use less power to turn the pulley (sheave). Furthermore, these elevators have the ability to lift loads up to 13600 kg.

        Gearless Traction Elevators

        These traction elevators have the wheel directly attached to the electric motor. Gearless traction elevators have a very high travel speed i.e. up to 2000 ft. per minute and can travel a great distance. Their maximum travel distance is almost 2000 ft. and thus they are the best and the only choice for high-rise buildings. Gearless traction elevators were first manufactured in 1914 by Otis and installed in Woolworth Building in NYC. These elevators had the ability to be employed in all kinds of buildings of any height and had a much higher speed than other hydraulic elevators. The gearless traction system, since then, has proven to be so durable that even today it is the best and most reliable option available for high-rise applications. These elevators function using a wire cable (hoisting ropes) which is attached to the elevator top and wrapped around the sheave on one end. The other end of the cable is attached with a counterweight that raises and lowers in the hoist way. The weight of the cab and counterweight together press the cable which then turns the sheave and the elevator begins moving. To keep the load on the electric motor minimum, the counterweight is matched with the weight of the elevator cab and half-load of the passengers.  As the elevator cab moves upwards, the counterweight begins to move downwards, and in this way it balances the elevator load. This significantly reduces the energy consumption as the motor only bears the weight of half the cab load.

          Machine Room-Less Traction Elevators

          Machine Room-Less Elevators were first manufactured by Kone in 1996 and have become very common in recent times. These traction elevators, as the name suggests, do not have an overhead machine room. In other traction elevators, the machine room is present over the elevator shaft, whereas in these elevators it is placed in the override space. When repair or maintenance is required, the machine room is opened from the top of the cab. Machine Room-Less Traction Elevators have the ability to travel up to a distance of 250 ft. and have a travel speed of up to 500 ft. per minute. Moreover, their installation and maintenance costs are somewhat comparable to those of geared traction elevators. However, Machine Room-Less Traction Elevators are more energy efficient as compared to geared traction elevators. These elevators are gaining popularity and becoming a common choice for mid-rise application where the travel is around 250 ft. It is because Machine Room-Less traction elevators traction elevators are highly energy efficient, fairly priced, require less space for installation, and their durability and reliability is comparable with gearless traction elevators. These type of elevators offer more design freedom and help utilize the hoist way better.