Question 36 1AE01 - First Assistant Engineer

The Correct Answer is A. **Why option A ("The filters and strainers should be checked frequently.") is correct:** When a new hydraulic pump is installed, even if the system was thoroughly cleaned beforehand, the act of installation itself can introduce contaminants, such as debris, dirt, or metal particles (swarf) left over from manufacturing, shipping, or the installation process. Additionally, the new pump may initially shed small internal wear particles during its break-in period. These contaminants are mobilized by the hydraulic fluid and will be captured by the system's filters and strainers. If these filters become saturated or clogged quickly, they can cause excessive pressure drop, trigger bypass, or lead to premature failure of other system components. Therefore, frequent checking (and replacement, if necessary) of the filters and strainers is essential immediately following new pump installation to ensure system cleanliness and prevent damage. **Why the other options are incorrect:** * **B) All system pressure should be readjusted:** System pressure settings are determined by the requirements of the machinery (e.g., actuator force, speed) and are controlled by pressure relief or reducing valves. Replacing a pump (which is a flow generator) generally does not require a blanket readjustment of all system pressures unless the old pump was severely failing and artificially affecting the pressure regulators, or if the new pump has vastly different flow characteristics that overwhelm the existing controls. In a standard replacement, pressure settings should remain the same. * **C) The relief valves in the system should be readjusted:** Similar to option B, relief valves are set to protect the system and determine maximum operating pressure. The new pump is designed to deliver flow up to that maximum pressure. Unless the pump replacement is part of a larger system redesign, the existing relief valve settings should be maintained, not readjusted. * **D) The system should be drained and renewed with a fluid of different operating characteristics:** Changing the type of hydraulic fluid (e.g., viscosity, anti-wear additives) should only be done if specified by the equipment manufacturer or required due to a significant change in operating temperature or application. Simply installing a new pump does not necessitate changing the fluid's operating characteristics, provided the original fluid was compatible and suitable for the application.