NEIEP Mechanics Practice Exam

During the operation of a hydraulic elevator, what happens when the up valve is closed?

1. The elevator descends

2. The elevator ascends

3. The elevator remains stationary

4. The elevator's speed increases

The correct answer is: The elevator descends

When the up valve is closed during the operation of a hydraulic elevator, the hydraulic fluid is prevented from entering the chamber that lifts the elevator car. This causes a buildup of pressure below the car, and since the weight of the elevator car is greater than the pressure in the system can support, the car will begin to descend. The system operates on the principle that if the force exerted by the hydraulic fluid is no longer sufficient to counteract the weight of the elevator, gravity will take over and cause the car to move downward. It is essential to note that when the up valve is closed, and no other valve is opened that allows hydraulic fluid to act against the weight of the elevator, the car cannot ascend nor remain in position unless action is taken to apply a locking mechanism. Therefore, the closed up valve mechanism effectively allows gravity to pull the elevator car downwards.