🔍 Key Concepts

• Relationship between steam pressure and whistle pitch/volume versus sound quality • How a mechanically loose component in a vibrating device affects the sound (rattle vs clear tone) • Function of the back cover and mounting parts shown in the illustration (label A/B/C area)

💭 Think About

• Look at the parts of the whistle that vibrate or are directly attached to vibrating parts: which one, if not secure, would be most likely to create a rattling noise? • Would low or high steam pressure usually change the tone quality to ‘rattling,’ or would it more likely just change loudness and pitch? • Which component in the choices would affect steam admission control, and which would affect mechanical tightness of the vibrating assembly?

✅ Before You Answer

• Identify which choice involves a mechanically loose cover or housing that could vibrate independently and rattle. • Distinguish between issues that change flow/pressure (pilot valve, steam pressure) and those that change mechanical rigidity (back cover tightness). • Ask whether the symptom is mainly about noise quality (rattle) or insufficient sound output, and match your choice to that symptom.