🔍 Key Concepts

• Review how a boiler expands when heated and why one support must be a fixed foot and the other a sliding foot. • Look closely at the lower illustration for the labeled parts around the Phosphor Bronze Chock Facing and any grease or oil fittings – these usually indicate a sliding surface. • Recall on a typical marine water‑tube boiler which end of the water drum is held fixed and which is allowed to move (front vs rear).

💭 Think About

• From the construction shown, does this support allow longitudinal movement, or does it clamp the drum rigidly in place? What specific features in the drawing prove that? • If the drum grows longer as it heats, in which direction must it be free to move so that stresses are not transmitted into the hull or uptakes? Match that with whether this would be at the front or rear. • Compare this foot to what you would expect for a purely fixed support – what elements would be missing or different if it could not slide?

✅ Before You Answer

• Identify whether the Phosphor Bronze Chock Facing and adjacent parts form a bearing/sliding surface or a solid block with no relative motion. • Verify which end of a standard marine boiler water drum is designated the fixed end in your study materials (front or rear). • Confirm that the presence (or absence) of any lubrication fitting or wear plate matches your choice of sliding vs fixed foot before selecting an option.