🔍 Key Concepts

• constant mesh gearing in a marine reversing reduction gear • role of clutches in selecting ahead vs astern power flow • what happens to the non‑selected gear train (ahead or astern) when its clutch is disengaged

💭 Think About

• If both forward and reverse pinions are in constant mesh with the main gear, which parts are always turning whenever the main gear turns? • When you engage one clutch (ahead or astern), what does that do to power flow, and what must be happening to the other pinion and its gears at the same time? • Does being in constant mesh tell you anything about air pressure systems or synchromesh devices, or only about how the gears themselves are physically engaged?

✅ Before You Answer

• Focus on what constant mesh means: teeth are always engaged, but torque only passes when a clutch connects that gear set to a shaft. • Eliminate any choices that introduce extra systems (air pressure, synchromesh) that are not shown or required by constant‑mesh design. • Make sure the remaining choice correctly describes the behavior of the non‑clutched (idling) gear set when the other direction is selected.