Short Answer:

A revolved section is a type of section where the internal shape of a part like a rod, arm, or spoke is shown by rotating the cut section 90 degrees and placing it directly on the main view. It helps show the shape without drawing a new view.

An aligned section, on the other hand, is used when a part has features like holes or ribs that are not in a straight line. The cutting plane is bent to pass through those features, and then the section is drawn as if all parts are aligned in a straight line, making it easier to understand.

Detailed Explanation:

Difference Between Revolved Section and Aligned Section

In mechanical engineering drawings, sectional views are used to make the internal features of components visible. Sometimes, standard full or half sections are not suitable for showing small or irregular internal shapes. In such cases, special types of sections like revolved sections and aligned sections are used.

Both of these are helpful for clear and simple representation, but they are used in different situations and have different methods of construction.

Revolved Section

A revolved section is created by:

• Cutting a small portion of a long object (like a shaft, arm, or spoke)
• Then rotating (revolving) the cross-section by 90 degrees
• Placing it directly on the view itself, without creating a separate view

It shows the shape of the cross-section clearly without requiring extra space on the sheet.

Where used:

• Arms, brackets, rods, spindles, machine levers, etc.
• When the cross-section shape needs to be shown quickly
• Especially helpful in thin or long parts

Example: A flat strip with a T-shaped cross-section can be drawn with a revolved section placed across the body to show the T-shape clearly.

Aligned Section

An aligned section is used when:

• The part has features (holes, slots, ribs) that are not in one straight line
• A single straight cutting plane would miss some features
• The cutting plane is bent or turned to pass through all features
• Then the features are “aligned” in one straight line in the final drawing

This gives a clear view of all the key features in one sectional view, even though the cut was not actually straight.

Where used:

• Crankshafts, connecting rods, objects with circular or curved holes
• Complex symmetrical parts
• Drawings where showing multiple cuts in one view helps avoid confusion

Example: A flange with holes placed on a curve—an aligned section lets you show all the holes as if they lie in a straight line.

Key Differences

Feature	Revolved Section	Aligned Section
Cutting Method	Straight cut, rotated in place	Bent cutting plane through multiple features
Position on Drawing	Placed directly on the main view	Drawn separately in place of front or side view
Usage	For showing cross-section of long parts	For showing all features in curved or angled parts
Appearance	Shows shape across the part body	Shows aligned features in a straight line
Common in	Shafts, arms, spokes	Flanges, curved parts, irregular layouts

Conclusion

A revolved section and an aligned section are both helpful ways of showing internal features that cannot be clearly displayed using regular section views. A revolved section shows the shape of a cut surface placed directly on the object, while an aligned section shows multiple internal features aligned in one view, even if the cut plane bends. These techniques make engineering drawings simpler, clearer, and easier to understand, especially when dealing with complex shapes or long parts.