Definition check: A worm may be regarded as a screw whose thread form corresponds to the rack tooth form of the mating worm gear, enabling conjugate meshing. Decide whether this statement is correct.

Introduction / Context:
Worm gears pair a screw-like worm with a helical gear (worm wheel) at right angles. The thread form of the worm is often described relative to the rack form used to generate the mating gear tooth. This item tests conceptual understanding of worm geometry and generation.

Given Data / Assumptions:

• The worm drives a worm gear with a specified module/DP and pressure angle.
• Hobbing tools are based on rack forms to generate involute teeth.
• Conjugacy requires matched profiles along the line of contact.

Concept / Approach:
Involute gears can be generated by a rack-shaped cutter. A worm can be viewed as a helical gear of high helix angle; its thread profile is equivalent to the rack tooth that properly mates with the worm gear. Thus, describing a worm as a screw with a rack-shaped thread conveys the generative relationship.

Step-by-Step Solution:
1) Fix module/DP and pressure angle for the pair.2) Use a rack-equivalent form to generate the worm gear teeth.3) Ensure the worm thread flank matches the rack form to maintain conjugacy.4) Verify center distance and lead for correct meshing.

Verification / Alternative check:
Gear-generation literature treats worm threads and hob cutters through rack equivalents; inspection of contact patterns confirms the match.

Why Other Options Are Wrong:
Fastener V-threads are not conjugate to involute gear teeth; they are not used for power worm drives.Claiming no relation to rack forms ignores the standard generative approach.

Common Pitfalls:
Mismatched pressure angles; neglecting lead errors; overlooking lubrication regimes in high sliding contact.

Final Answer:
Correct