A jaw crusher compresses stone between a fixed jaw and a moving jaw, with a narrowing passage toward the outlet. Explore the mechanism in Blake's 1858 patent and compare two representative feed and product sizes using the calculator.
Feed-to-Product Size Comparison Calculator
Enter one declared representative feed size and one declared representative product size. The worksheet reports their arithmetic ratio and change only; it does not predict a crusher's product distribution, capacity, outlet setting, power, wear or suitability.
Equation Used
- Feed and product values are positive declared representative sizes in the same unit.
- Reduction ratio is the dimensionless arithmetic quotient F/P.
- Size change and percent reduction are signed, so a product value at or above the feed value is not described as a reduction.
- Particle distributions, shape, hardness, moisture, jaw dimensions, stroke, nip behavior, chamber profile, capacity, power, wear, clearances, stresses and safety are excluded.
The drive moves one jaw toward and away from the fixed jaw. The calculator compares the entered feed and product sizes; it does not derive those sizes from the animation or predict crusher performance.
A fixed jaw and a short-vibrating movable jaw
Blake's 1858 patent describes two nearly upright jaws converging downward. One jaw is fixed. The other receives a short, powerful vibration through a crank, connecting rod, lever and elbow-joint arrangement while its lower end is constrained in the frame.
Stone enters at the wider top opening, is crushed between the jaws, falls lower when the jaw retreats, and is crushed again. Fragments repeat that sequence until they can pass the narrower bottom opening.
A historical crushing principle, not an equipment selector
The patent describes crushing stone and ore with reciprocating jaws. Comparing representative feed and product sizes expresses a desired or measured size change, but does not establish which machine or operating conditions can achieve it.
Real crushing equipment requires manufacturer data, material testing, guarding, dust and noise controls, safe procedures and qualified engineering.
Representative size relationships
These are identities between two entered representative sizes. They do not calculate the historical jaw geometry, a size distribution, outlet setting, capacity, power or required number of stages.
Declared size example
For F=600 mm and P=150 mm, the declared size ratio is 4.000:1, the signed change is 450.0 mm, the product/feed fraction is 0.250 and the signed size reduction is 75.0%.
The example does not state that a particular crusher will transform every 600 mm particle into a 150 mm product.
Particle sizes and machine performance
Blake notes that proportions vary with the intended stone size and hardness. His example dimensions and motion are historical description, not universal design rules.
Actual output depends on the material and machine, including particle-size distribution, chamber shape, stroke and operating conditions. The entered representative product size is not a calculated outlet gap, and the ratio does not predict throughput or motor power.
Ore-crusher questions
Is the entered product size the jaw outlet gap?
No.
Does a 4:1 size ratio prove one machine can achieve that reduction?
No.
Does the animation determine stroke or nip angle?
No. It is a connected schematic of the patent topology.
Does this size a motor or predict capacity?
No.
Is this operating or maintenance guidance?
No.
Ore-crusher reference
- Eli Whitney Blake, US Patent 20,542, Machine for Crushing Stone, 1858: primary patent description and drawings for the fixed jaw, vibrating movable jaw, elbow joint, lever, connecting rod, crank and repeated downward crushing path.
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