How Does Jaw Crusher Realize Stone Crushing Process

How Does Jaw Crusher Realize Stone Crushing Process

Introduction

A jaw crusher breaks massive hard stones into small qualified aggregate through a continuous cycle of feeding, squeezing, fracturing and discharging. The whole crushing process relies on the periodic reciprocating swing of the movable jaw plate inside the V-shaped crushing cavity. Below is a step-by-step breakdown of the full stone crushing workflow.

Step 1: Feeding – Raw Stones Enter the Crushing Cavity

Large lumps of rock, ore or construction waste are evenly sent into the top feeding opening of the jaw crusher by a vibrating feeder or manual feeding.

All raw materials fall into the wedge-shaped V cavity formed by the fixed jaw and movable jaw. The cavity width shrinks gradually from top to bottom: the upper part holds oversized raw blocks, while the narrow bottom serves as the discharge outlet for finished small stones.

Step 2: Power Transmission Drives Movable Jaw to Swing

The motor outputs rotating power, which passes through V-belts to drive two flywheels mounted on the eccentric shaft.

As the eccentric shaft spins, its offset cam converts circular rotation into back-and-forth swinging motion of the movable jaw. A toggle plate under the movable jaw provides thrust support, and a tension spring pulls the movable jaw back after each crushing stroke. This forms a repeated forward-and-back swing loop.

Step 3: Compression Stroke – Stones Are Cracked by Multi-Force Extrusion

When the eccentric shaft pushes the movable jaw toward the fixed jaw, the internal space of the crushing cavity rapidly contracts. Trapped stones bear three combined destructive forces at the same time:
  1. Direct extrusion force: Two jaw plates squeeze the stone from opposite sides, compressing its internal structure;
  2. Bending force: Irregular rock shapes create uneven stress, bending the stone to produce internal cracks;
  3. Splitting shear force: Ridged tooth profiles on the jaw plates cut and split the rock from local contact points.
Hard brittle materials like granite, basalt and limestone have weak tensile resistance. Tiny internal cracks expand instantly under compound force until the rock splits into multiple fragments. Extra-large blocks in the upper cavity are crushed multiple times in layers.

Step 4: Release Stroke – Qualified Fragments Fall by Gravity

When the eccentric shaft rotates to the offset reverse position, the tension spring pulls the movable jaw away from the fixed jaw. The gap inside the crushing cavity widens suddenly.
  • Stone fragments smaller than the bottom discharge opening gap slide down along the jaw plates and exit the crusher as finished products;
  • Larger uncrushed rock chunks remain suspended in the middle and upper section of the V cavity, staying inside for the next round of extrusion crushing.

Step 5: Circulating Layered Crushing

The movable jaw repeats forward compression and backward release continuously. Raw stones go through layered crushing from top to bottom automatically:
  1. Oversized lumps are broken in the upper wide cavity;
  2. Medium-sized fragments are re-squeezed in the middle area;
  3. Small particles meeting size standards drop out from the bottom.

    No extra screening equipment is needed for primary rough crushing, forming an uninterrupted automatic crushing circulation.

Step 6: Discharge Size Regulation to Control Finished Stone

The width of the bottom discharge opening decides the particle size of final crushed stone. Operators adjust the rear wedge adjusting seat to move the toggle plate forward or backward:
  • Narrow the discharge gap to produce fine aggregate;
  • Widen the gap to output coarse large stones.

    All adjustments must be performed after shutting down the machine to avoid safety hazards.

Step 7: Overload Protection During Crushing Process

If uncrushable foreign objects (iron blocks, steel bars) accidentally fall into the cavity, the instantaneous pressure exceeds the machine’s load limit. The toggle plate, designed with weak breakage grooves, fractures automatically to cut off thrust on the movable jaw. The crushing process stops immediately to protect expensive core parts like the eccentric shaft, bearing and main frame from severe damage. After removing foreign matter and replacing a new toggle plate, crushing can resume.

Difference in Crushing Process: Single Toggle vs Double Toggle Jaw Crusher

  1. Single toggle jaw crusher (mainstream model)

    The movable jaw follows an elliptical swing track. Besides horizontal extrusion, slight vertical friction exists, accelerating crushing speed with high throughput. Suitable for most quarry and mine stone processing.

  2. Double toggle jaw crusher

    The movable jaw only makes pure horizontal reciprocating movement without vertical friction. Stone abrasion on jaw plates is milder, with stronger crushing force. It is used for ultra-hard rock crushing with strict wear requirements.

Full Crushing Process Summary

  1. Large stones are fed into the V-shaped crushing cavity from the top inlet;
  2. Motor and eccentric shaft drive the movable jaw to swing back and forth periodically;
  3. Movable jaw advances to squeeze and split rocks via extrusion, bending and shear force;
  4. Movable jaw retreats, small qualified stones drop out from the bottom outlet;
  5. Unbroken large chunks circulate for repeated layered crushing;
  6. Adjust the discharge gap to control finished stone particle size;
  7. Toggle plate breaks automatically to stop crushing and protect equipment under overload.