🔍 Key Concepts

• Double articulated reduction gear layouts and which parts rotate at high vs low speed • How a quill shaft is positioned relative to pinions and gears • Visual differences between a shaft and a gear/pinion in a cross‑section drawing like SE-0005

💭 Think About

• Look at where label 3 is pointing: is it marking a toothed gear, a smooth shaft, or the supporting structure for another part? • In a double reduction gear, which elements are directly connected to the turbine (high speed) and which are connected to the output shaft (low speed)? • How does an articulated or quill shaft allow for slight misalignment between the turbine and the main gear train?

✅ Before You Answer

• Confirm whether the part at 3 has gear teeth or is a smooth cylindrical shaft • Check whether 1 and 2 are already identifying the main shaft and gears so you don’t name the same type of part twice • Verify that your chosen term matches the function of the part at 3 in carrying torque between high‑speed pinions and the main gear (power-transmitting shaft vs meshing gear)