In my experience, not all elevators have counterweights. Let me explain.
Counterweights are commonly found in modern elevators and play an important role in their operation. They are typically attached to the other end of the pulley system, and their weight is roughly equivalent to that of the elevator car when it is at 50% loading. The purpose of the counterweight is not to do all the work in lifting the car, but rather to help stabilize the system and reduce the load on the elevator motor.
However, it is worth noting that not all elevators rely on counterweights. Some older and smaller elevators may not have counterweights due to their simpler design and lower weight capacity. These elevators may use other mechanisms, such as hydraulic systems, to lift the car.
I recall encountering an older elevator in a historical building that did not have a counterweight. It was a small elevator with a manually operated door and a basic pulley system. This elevator relied solely on the power of the motor to lift the car, without the assistance of a counterweight. While it was slower and had a lower weight capacity compared to modern elevators, it still served its purpose in transporting people between floors.
While counterweights are commonly found in modern elevators, not all elevators have them. The presence or absence of a counterweight depends on factors such as the design, weight capacity, and age of the elevator.