How to Adjust the Discharge Opening of a Jaw Crusher
The discharge opening, often referred to as the “closed side setting” (CSS), is a critical parameter in jaw crusher operation. It directly determines the maximum size of the crushed product output and significantly impacts crusher capacity, power draw, and wear life. Knowing how to correctly and safely adjust this setting is essential for optimizing performance and achieving desired product specifications. There are two primary methods for adjusting the discharge opening on jaw crushers: mechanical adjustment using shims or wedges, and hydraulic adjustment.
1. Mechanical Adjustment (Shims or Wedges)
This traditional method is common on many older and smaller jaw crushers. It involves physically adding or removing components to alter the position of the toggle plate relative to the fixed jaw.
Preparation:
Safety First: Ensure the crusher is completely shut down following proper lockout/tagout (LOTO) procedures. Disconnect all energy sources.
Access: Open any necessary access doors or covers to reach the rear of the toggle seat or adjustment mechanism.
Cleanliness: Clean any accumulated dust or debris from around the adjustment area.
The Adjustment Process:
Locate Components: Identify the toggle seat block at the rear of the movable jaw frame and its counterpart on the crusher frame.
Shim Method: The gap between these blocks is filled with precisely manufactured steel shims (plates). To decrease the CSS (make a finer product), carefully add shims of equal thickness behind both toggle seat blocks, pushing them further apart. To increase the CSS (make a coarser product), remove an equal number of shims from both sides.
Wedge Method: Some designs use opposing wedge pairs driven by screws. Turning one screw clockwise typically pushes its wedge inward, forcing the blocks apart (decreasing CSS). Turning it counter-clockwise allows relaxation (potentially increasing CSS if tension is released, often requiring manipulation of both wedges). Always consult your specific machine’s manual for exact procedures.
Symmetry is Key: Crucially, adjustments must be made equally on both sides of the crusher simultaneously. Uneven adjustment will cause uneven wear on jaws and bearings, leading to premature failure and potentially dangerous imbalance.
Reassembly & Check: Once shims are added/removed or wedges positioned:
Re-tighten any locking
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