🔍 Key Concepts

• How a hydraulic clutch / fluid coupling transmits torque using oil between the impeller (driving side) and runner (driven side) • What must happen to the oil inside the coupling (look at the ring valve, drain, and oil inlet in the illustration) for the clutch to fully disengage • How oil level and viscosity affect how quickly oil can drain out and stop torque transmission

💭 Think About

• Trace the oil’s path in the illustration: when you move the actuating lever to disengage, what has to physically happen to the oil between the impeller and runner before the driven shaft can truly stop? • Which condition would tend to keep more oil in the working space between impeller and runner, or slow its escape through the drain, so that torque continues to be transmitted longer than desired? • Between temperature changes and contamination, which factor would most directly affect the amount of oil remaining in the coupling rather than just the ease of pumping it?

✅ Before You Answer

• Identify which options would cause excess oil to remain in the coupling versus those that mainly affect viscosity or possible sticking of parts. • Consider whether higher or lower temperature would make the oil drain faster or slower, and whether that matches a longer disengage time. • Ask: which condition would most directly delay the emptying of oil from the working chamber shown between the impeller and runner in the illustration?