Hammer crusher fundamentals: Which statement set best characterizes hammer crushers used for primary or secondary size reduction?

Introduction / Context:
Hammer crushers (or hammer mills) are widely used for brittle materials (limestone, shale, gypsum). Understanding their operating principle, feed limitations, and methods to control product size is a core mechanical operations topic.

Given Data / Assumptions:

• Brittle feed materials, moderate hardness.
• Industrial machines with breaker plates/cages and adjustable settings.
• Typical feed size in coarse service can be several tens of centimeters.

Concept / Approach:

Hammers rotating at high tip speed impart impact forces that fracture particles. Product size is controlled by grate bars, cage settings, or breaker plate clearances. Feed size limits depend on rotor diameter and design but often approach ~300 mm for primary units.

Step-by-Step Solution:

Verification / Alternative check:

Manufacturer data sheets show impact breakage, adjustable grate/clearance, and feed size ranges compatible with the values cited.

Why Other Options Are Wrong:

Choosing any single statement ignores the others which are also correct; the comprehensive answer is that all apply.

Common Pitfalls:

Confusing hammer crushers with roll or jaw crushers (compression-dominant); overlooking that exact feed size depends on equipment scale.

Final Answer:

All of the above