Jaw crusher overload shutdown fault troubleshooting

Jaw crusher overload shutdown fault troubleshooting

1. Overview

Overload shutdown is one of the frequent protective actions of jaw crushers. The equipment cuts off power automatically to avoid damage to the main motor, bearing, toggle plate and frame. It is divided into genuine overload and false overload alarm.

2. Step-by-step Troubleshooting Procedure

Step 1: Lockout & Tagout (LOTO) – Safety First

Cut off the main power supply, hang warning signs. Do not enter the crushing chamber before the flywheel stops completely. Confirm the reset state of thermal relay, current protector or PLC overload signal.

Step 2: Check Material Feeding & Cavity Blockage (Most Common Cause)

  • Symptom: High instantaneous current, shutdown soon after feeding; large amount of stock inside crushing cavity.
  • Root causes:
    1. Oversized raw ore enters the cavity, cannot be crushed and gets wedged.
    2. Continuous overfeeding, feeding rate exceeds crusher processing capacity.
    3. Wet, sticky ore mixes with mud, causing material bridging and clogging.
    4. Foreign objects (iron block, steel bar, shovel head) fall into the crushing chamber.
  • Solutions:
    • Clean blocked materials manually with professional tools; never pry blocked rock by starting the machine repeatedly.
    • Control feeding size strictly according to the crusher’s maximum feed opening.
    • Install iron remover before feeding hopper.
    • Reduce feeding speed for sticky wet materials.

Step 3: Check Discharge Opening Setting

  • Symptom: Even normal-size rock triggers overload; discharge gap is too small.
  • Root cause: Discharge opening adjusted too narrow, finished material cannot be discharged timely, material stacking inside cavity forms choked crushing.
  • Solution: Widen the discharge opening to the recommended value, test run and observe current.

Step 4: Mechanical Resistance & Friction Abnormity

  1. Jaw plate loose or offset: Loose liner causes uneven squeezing, extra load. Retighten wedge bolts, check jaw plate fit.
  2. Bearing failure: Bearing lack of lubrication, overheating, wear or roller damage. Rotate flywheel manually; if rotation is stiff or has abnormal noise, disassemble and replace bearing, recheck lubrication circuit.
  3. Toggle plate / toggle seat jam: Check toggle plate for crack, dislocation or stuck debris. The toggle plate is the safety part; it will break under severe overload.
  4. Flywheel, V-belt problem: Belt overtension increases motor load; slipping may also trigger current fluctuation alarm. Adjust belt tension evenly, inspect for cracks.

Step 5: Power & Electrical System Inspection (False Overload)

  • Symptom: No blockage, crusher turns freely by hand, but overload protection trips frequently.
  • Root causes:
    1. Unstable three-phase power supply, voltage drop under load.
    2. Thermal overload relay parameter set too low, aging or drift.
    3. Motor winding insulation aging, single-phase operation.
    4. Cable aging, loose terminal connection causing abnormal current.
  • Solutions:
    • Test three-phase voltage and current balance.
    • Recalibrate or replace the thermal relay according to motor rated current.
    • Inspect motor winding resistance and temperature.
    • Fasten all electric terminals.

Step 6: Lubrication System Inspection

Insufficient lubrication, blocked oil pipeline, deteriorated grease will sharply increase friction resistance and induce overload shutdown.

  • Check oil level, oil temperature and oil pressure.
  • Clean lubrication pipeline, replace expired lubricant.
  • Confirm automatic grease pump works normally.

3. Quick Judgment Table

表格

Phenomenon Suspected Fault
Trips immediately when feeding, cavity full of rock Cavity blockage / oversized feed
Trips after running a while, bearing housing hot Bearing poor lubrication or wear
No load idling also triggers overload trip Electrical fault, relay misoperation, mechanical jamming
Toggle plate broken after overload shutdown Severe mechanical overload, foreign iron mixed in

4. Prevention Measures

  1. Standardize feeding, equip vibrating feeder and metal detector.
  2. Regularly check jaw plate wear, bearing temperature and lubrication.
  3. Do not arbitrarily increase the setting value of overload protection.
  4. Set current real-time monitoring on the control cabinet.
  5. Operators should stop feeding immediately once hearing abnormal sound or seeing current surge.

5. Warning

Do not short-circuit or remove the overload protection device. This will lead to serious damage of the crusher body and major safety accidents.