Jaw Crusher Capacity & Reduction Calculator
Calculate crushing reduction ratios (F80 to P80), Closed Side Setting (CSS), hourly throughput capacity (TPH), and Bond Work Index power.
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How Jaw Crusher Reduction & Tonnage Sizing Work
Primary jaw crushers fracture blasted rock under severe compressive force between a stationary and moving jaw die:
Reduction Ratio = Feed Size (F80) / Product Size (P80)
Product Size (P80) ≈ Closed Side Setting (CSS)
Throughput TPH ≈ Base Capacity Factor × Jaw Width × CSS Multiplier × Prescreen Factor
Max Feed Size = 0.80 × Gape Opening
Reduction Ratio Warning: Primary jaw crushers operate most efficiently between 4:1 and 6:1 reduction ratios. Exceeding 7:1 or 8:1 forces rocks to pack tightly in the crushing chamber (choke feed stalls), increasing jaw die wear and risking toggle plate breakage.
Frequently Asked Questions
What is the Closed Side Setting (CSS) on a jaw crusher?
The Closed Side Setting is the narrowest distance between the fixed jaw and the swinging jaw plate at the bottom discharge opening during the peak forward crushing stroke. The CSS determines the top size of the crushed aggregate product.
Why should maximum feed rock size not exceed 80% of the gape?
If a 30" × 42" crusher attempts to crush a 30-inch boulder, the rock cannot drop deep enough into the crushing chamber for the jaw teeth to obtain a firm bite. Instead, the boulder bridges across the mouth or bounces violently, halting production until a hydraulic rock breaker splits it.
What is the purpose of the safety toggle plate in a jaw crusher?
The toggle plate acts as a mechanical fuse. If an uncrushable piece of tramp iron (like an excavator tooth) enters the chamber, the cast iron toggle plate snaps cleanly in half, allowing the swing jaw to fall backward and preventing the heavy eccentric crankshaft from bending.