NEIEP Mechanics Practice Exam

In a hydraulic elevator system, what is the primary purpose of a check valve?

1. To measure fluid flow

2. To prevent backflow

3. To regulate pressure

4. To increase lift speed

The correct answer is: To prevent backflow

The primary purpose of a check valve in a hydraulic elevator system is to prevent backflow. Check valves ensure that fluid can only flow in one direction, which is crucial in maintaining the proper operation of the hydraulic system. When the elevator is at rest or descending, the check valve closes automatically to stop hydraulic fluid from flowing back into the reservoir, which could compromise the elevator's ability to hold its position or cause a malfunction. This function is essential for safety, as it helps maintain the integrity of the elevator system and prevents uncontrolled descent. Other functions such as measuring fluid flow, regulating pressure, or increasing lift speed are typically the roles of different components in the hydraulic system, such as flow meters, pressure regulators, or variable speed drives. Therefore, the check valve's specific role in backflow prevention is fundamental for the reliable and safe operation of hydraulic elevators.