Draw a thrust block, describe its parts, explain how propeller thrust reaches the hull, and state how to measure thrust clearances?

flowchart LR
    A[Propeller] -->|thrust| B[Tail shaft]
    B --> C[Intermediate shaft]
    C --> D[Thrust shaft]
    D --> E[Thrust collar]
    E --> F[Thrust pads]
    F --> G[Pad carriers]
    G --> H[Hull via foundation]

• Thrust shaft: keyed to transmit torque, allows axial movement
• Thrust collar: forged steel disc keyed to thrust shaft, bears against thrust pads
• Thrust pads: lined segments, low-friction surface, take axial load
• Pad carriers / shoes: hold pads, allow slight tilting
• Housing / casing: encloses assembly, bolted to ship’s double bottom or seatings
• Hold-back devices: prevent pad rotation, maintain position during thrust reversal
• Cooling arrangement: oil scraper rings, cooling coils or dedicated lube oil system
• Thrust transmission: propeller → tail shaft → intermediate shaft → thrust shaft → thrust collar → thrust pads → pad carriers → housing → hull
• Clearance measurement: stop shaft, lock turning gear, use feeler gauges between pad and collar at multiple points, record readings
• Clearance check: compare with maker’s limits, report excessive/uneven wear