Which of the following is not a component of a traction elevator?

In a traction elevator system, the key components include the sheave (or pulley), counterweight, and motor. The sheave is responsible for guiding the steel cables that lift the elevator car as the motor turns the sheave. The counterweight balances the weight of the elevator car and helps reduce the amount of energy needed to move the car, making the system more efficient.

The motor provides the necessary power to move the sheave, which in turn moves the elevator car.

A piston, however, is not part of a traction elevator; instead, it is a critical component of a hydraulic elevator system. In hydraulic elevators, the piston extends and retracts to raise and lower the car, utilizing fluid pressure to move the car vertically. This distinction clarifies that the piston is specific to hydraulic systems and does not function in a traction elevator setup, making it the right answer for identifying a component that is not part of a traction elevator.