Hydraulic Systems Flashcards

What causes aeration in a hydraulic system?

Answer: Air being drawn into the pump inlet through loose fittings, low fluid level, or damaged suction line

Aeration occurs when air is drawn into the hydraulic fluid, commonly through loose suction fittings, cracked suction lines, low reservoir fluid level (exposing the suction port), or a damaged pump shaft seal.

What is a hydraulic motor and how does it differ from a hydraulic cylinder?

Answer: A hydraulic motor converts fluid pressure into continuous rotary motion, while a cylinder converts it into linear motion

A hydraulic motor converts hydraulic fluid pressure and flow into continuous rotary motion (torque and speed), while a hydraulic cylinder converts fluid pressure and flow into linear motion (force and stroke). Both are actuators but produce different types of motion.

What should be checked first when a hydraulic system operates slowly?

Answer: The fluid level, pump output flow, and system pressure

Slow operation indicates insufficient flow reaching the actuators. Check fluid level (low level causes cavitation), pump output flow (worn pump or wrong speed), and system pressure (relief valve set too low or excess leakage stealing flow).

What is the advantage of a servo hydraulic valve over a proportional valve?

Answer: Higher frequency response and more precise control for applications requiring very fast and accurate positioning

Servo valves offer much higher frequency response, tighter null characteristics, and more precise flow control than proportional valves, making them suitable for applications requiring very fast response and precise positioning, such as machine tool axes.

Why is the return line filter important in a hydraulic system?

Answer: It captures contaminant particles generated by component wear before they return to the reservoir and recirculate

Return line filters capture wear particles, seal fragments, and other contaminants generated during system operation before the fluid returns to the reservoir. This prevents contaminated fluid from being recirculated and damaging pump and valve components.

What safety precaution must be taken before disconnecting any hydraulic line?

Answer: Relieve all system pressure, lock out the pump, and verify zero pressure with a gauge

Before disconnecting hydraulic lines, all pressure must be relieved (including accumulator pressure), the pump must be locked out/tagged out, and zero pressure must be verified with a gauge. Residual pressure can cause high-velocity fluid injection injuries.