Elevator Mechanic Practice Exam

If a hydro elevator runs with no load but won’t run with a full load, what is likely the problem?

1. Pump failure

2. Relief valve set too low

3. Oil temperature too low

4. Oil level too high

The correct answer is: Pump failure

The situation described indicates that the hydro elevator functions without a load but fails to operate when fully loaded. This suggests a potential issue with the system's ability to generate the necessary pressure to lift the full weight. When the elevator is unloaded, it requires less hydraulic pressure to raise the car, leading to normal operation. However, under a full load, the system needs to produce sufficient pressure to counteract the weight. If there is a failure in the pump, it may not be supplying the needed hydraulic fluid pressure to move the elevator, which explains why the system works when unloaded but cannot lift when fully loaded. While other options might suggest issues that could affect performance, they typically wouldn't lead to a complete failure to operate under load in the same way that a failed pump would. For example, a relief valve that is set too low may allow operation under certain conditions but would restrict performance, while low oil temperature generally influences the viscosity and flow characteristics, possibly leading to operational issues but not a total failure. An oil level that is too high would not generally prevent operation but could lead to other concerns. Thus, identifying pump failure as the likely issue aligns with the symptoms of the elevator's performance under differing load conditions.