Receiver-Type Compound Engine — Relative Crank Positions In a receiver-type compound steam engine (separate HP and LP cylinders with an intermediate receiver), the effective crank positions of HP and LP are generally considered to be:

Introduction / Context:
Compound engines split expansion between a high-pressure (HP) and a low-pressure (LP) cylinder. The receiver stores steam between the cylinders. Crank phasing influences torque smoothness and receiver pressure fluctuations.

Given Data / Assumptions:

• Receiver-type compounding with two separate cranks.
• Objective: uniform turning moment and practical receiver sizing.
• Typical marine or stationary compound engine practice.

Concept / Approach:
Setting cranks approximately 90° apart provides phase separation of HP exhaust and LP admission, promoting steadier receiver pressure and more uniform torque over the cycle. Other angles are sometimes used, but right-angle cranking is the standard textbook assumption for even turning moment.

Step-by-Step Solution:
Consider HP exhaust timing → LP admission timing should be offset to smooth receiver pressure.With 90° separation, peaks and troughs of indicated torque are interleaved, reducing fluctuation.Hence the cranks are regarded as 90° to each other.

Verification / Alternative check:
Turning-moment diagrams show lower fluctuation factor for multi-cylinder engines with cranks spaced at 90° or evenly distributed.

Why Other Options Are Wrong:

• 0°: Tandem compounding, not receiver type.
• 180°: Produces large torque fluctuation and unfavorable receiver dynamics.
• None of these: Unnecessary; 90° is the standard arrangement.

Common Pitfalls:
Confusing receiver-type with tandem (same crank) or cross-compound with different phase angles chosen for special duty.

Final Answer:
90° to each other