Hydraulic Systems & Pneumatics Flashcards

What is the recommended method for checking hydraulic fluid level in heavy construction equipment?

Answer: Check the sight glass or dipstick with the machine on level ground and cylinders retracted

Hydraulic fluid level must be checked with the machine parked on level ground and all cylinders fully retracted, ensuring all fluid has returned to the reservoir for an accurate reading.

What does a milky or foamy appearance in hydraulic fluid most likely indicate?

Answer: Water contamination has entered the hydraulic system

A milky or foamy appearance in hydraulic fluid indicates water contamination, which forms an emulsion with the oil, causing corrosion, reduced lubrication, and potential hydraulic system failure.

What is the primary cause of hydraulic system overheating during equipment operation?

Answer: Continuous operation with a partially open or bypassing relief valve

Continuous operation with a partially open relief valve forces fluid to bypass repeatedly, converting hydraulic energy to heat through throttling losses, which rapidly overheats the system.

When replacing hydraulic filters, what is the most critical safety precaution that must be taken first?

Answer: Relieve all system pressure and wear appropriate PPE before removing any filter

All system pressure must be relieved and appropriate PPE must be worn before replacing hydraulic filters, because pressurized hydraulic fluid can penetrate skin and cause severe injection injuries.

What is the primary function of a hydraulic accumulator in a heavy equipment system?

Answer: To store hydraulic energy and dampen pressure surges

A hydraulic accumulator stores hydraulic energy using a pre-charged gas bladder, which can smooth pressure surges, supply emergency power if the pump fails, and supplement pump flow during peak demand.

Which type of contamination is generally considered most damaging to hydraulic system components?

Answer: Particulate (solid) contamination from dirt, wear debris, or seal material

Particulate contamination is most damaging because solid particles cause abrasive wear on the extremely close-tolerance surfaces of pumps, directional valves, and actuators, leading to accelerated failure.

What action must be taken when a hydraulic hose shows visible signs of abrasion, chafing, or bulging?

Answer: Remove the equipment from service immediately and replace the damaged hose

Any hydraulic hose showing external damage must be replaced before further operation, as failure of a high-pressure hose can cause life-threatening fluid injection injuries and serious burns.