How to Measure the Jaw Crusher Gap (CSS)?

The jaw crusher gap, also known as the Closed Side Setting (CSS), is one of the most important settings on a jaw crusher. It determines the minimum distance between the fixed and moving jaw at the bottom and directly controls the size of the crushed output. Accurate measurement is critical—even a small miscalculation can ruin product quality or damage the crusher. Here’s how to do it:

Tools Needed:

● Feeler gauge (for small gaps, 0–50mm)
● Calipers or measuring rod (for larger gaps)
● Manufacturer-provided gauge (if available)

Step-by-Step Measurement:

● Shut Down the jaw Crusher: Ensure the machine is off, locked, and cool.
● Access the Discharge Opening: Clear any leftover material from the bottom of the jaws.
● Measure the Narrowest Point: The CSS is the smallest distance between the fixed and moving jaws at the bottom of the chamber. Insert your tool here.
● Check Uniformity: Measure at 2–3 points across the width of the jaws to ensure the gap is even (uneven gaps indicate worn jaw plates).
● Compare to Target: Cross-reference your measurement with the desired CSS (e.g., 50mm for road base). Adjust if needed.

Pro Tips for Jaw Crusher Gap Adjustment

● Follow Manufacturer Specs: Never exceed the maximum CSS for your crusher model—this can cause jams or break components.
● Adjust Gradually: Small increments (5–10mm) prevent sudden stress on the machine.
● Track Wear: Jaw plates wear unevenly. If measurements are inconsistent, replace the plates before adjusting the gap.
● Record Settings: Note the CSS and corresponding bolt positions for different materials (e.g., 30mm for concrete, 75mm for limestone) to save time later.
● Inspect Regularly: Check the CSS daily for high-volume operations—wear accelerates with heavy use.

Measuring CSS involves assessing the smallest gap between the fixed and moving jaws, either through the feed/discharge opening or via built-in indicators. Regular measurement ensures product size control and prevents equipment damage. Always prioritize safety and refer to the crusher’s operator manual for model-specific instructions. Clink this to know more about How to adjust jaw crusher gap.