Mobile Crushing Plant Problems

A mobile stone crusher plant works hard every day. Rocks, concrete, and asphalt go in. Crushed aggregate comes out. But no machine runs forever without problems.

Four faults happen more often than others. Crusher not feeding. Excessive vibration. Oversize discharge. Belt misalignment.

Learn to spot these mobile crushing plant problems early. Fix them fast. Get back to crushing.

Crusher Not Feeding – How to Fix No Feed to Crusher

The machine runs. The engine sounds normal. But no material goes into the crusher. This is a common mobile crusher machine problem.

What causes no feed to crusher:

Feeding too fast – Material piles up at the feed opening. The hopper fills. New material has nowhere to go.

Feeding too slow – The feeder does not get enough material. The crusher runs empty. This wastes fuel and wears parts faster.

Feeder jam – A large rock or piece of rebar blocks the feeder. Material stops moving.

Correct feeding method:

Keep the hopper about half full. Do not dump a whole load at once. Feed at a steady rate. Let the crusher process before adding more.

Crusher jammed solution:

Stop the machine. Clear the jam by hand or with tools. Never reach into the crusher while it is running. Check the material size. Oversize rocks cause jams.

Mobile crusher troubleshooting tip:

Watch the feeder for 5 minutes. If material builds up, slow down the feed. If the feeder runs empty, speed up. The correct feeding method keeps material moving steadily.

Excessive Vibration – How to Reduce Crusher Vibration

A crusher shakes. That is normal. But excessive vibration is different. The whole machine shakes. Bolts loosen. Parts crack. Operators feel it in their feet.

What causes crusher vibration problem:

Worn hammerheads or jaw plates – Crusher wear parts replacement is needed when hammerheads wear unevenly. One side heavier than the other causes imbalance. The machine vibrates.

Loose bolts – Daily shaking loosens bolts over time. A loose bolt on the crusher frame or motor mount causes extra movement.

Unstable base – A tracked crusher on soft ground sinks. A wheeled crusher on uneven ground rocks. The machine needs a solid base.

How to reduce crusher vibration:

Check hammerheads and jaw plates every week. Replace when worn. A set of worn hammerheads weighs less than new ones. Mixing old and new causes imbalance.

Tighten all bolts every month. Use a torque wrench. Mark bolts with a paint pen after tightening. You will see which ones move.

Move the machine to solid ground. For tracked crushers, soft ground is fine. For wheeled crushers, use blocks to level the machine.

When to call for help:

If vibration continues after checking these items, the main bearing or flywheel may be damaged. Stop using the machine. Contact a technician.

Oversize Discharge – How to Adjust Crusher Discharge Size

The finished material comes out too big. A road base job needs 20-40mm. You get 60mm pieces. A sand plant needs 0-5mm. You get pebbles.

What causes oversize discharge:

Worn hammerheads or jaw plates – Worn parts cannot crush to the correct size. The gap between the hammerhead and the screen gets larger.

Screen deck hole too large – The wrong screen mesh lets oversize material pass through.

Crusher discharge setting wrong – The gap setting on a jaw crusher or cone crusher controls output size.

How to adjust crusher discharge size:

Check hammerhead wear. If worn more than 50 percent, replace them. New hammerheads produce finer material.

Change the screen deck to a smaller hole size. For 0-5mm sand, use a 5mm screen. For 10-20mm aggregate, use a 20mm screen.

Adjust the crusher setting. On a jaw crusher, close the gap between the moving and fixed jaw. On a cone crusher, raise the mantle or lower the bowl.

Mobile crusher maintenance tip:

Keep a log of discharge size. Check a sample every hour. If the size changes, stop and inspect. Catching the problem early saves rework.

Belt Misalignment – How to Fix Conveyor Belt Tracking

The conveyor belt runs off center. It rubs against the frame. Material spills off the side. The belt wears out fast.

What causes belt misalignment:

Conveyor belt tracking issue – The belt tension is uneven. One side tighter than the other pulls the belt to the tight side.

Roller misalignment – A roller that is not square to the frame pushes the belt sideways.

Material loading off center – Material drops onto the belt from one side. The belt drifts to the opposite side.

How to fix conveyor belt tracking:

Adjust belt tension. Loosen the adjustment bolts on the tail roller. Tighten one side slightly. Run the belt for 30 seconds. See which way it moves. Adjust until the belt runs straight.

Check all rollers. Use a straight edge across the frame. Rollers should be square. Bend or replace bent rollers.

Center the material feed. Install a chute or guide to drop material in the middle of the belt. A centered load keeps the belt straight.

Fix conveyor belt tracking fast:

Most belts have a tracking roller near the head pulley. Turn the adjustment bolt one quarter turn at a time. Small changes work better than big ones.

Prevention – Mobile Crusher Maintenance Schedule

Most mobile crushing plant problems come from skipping basic maintenance.

Mobile crusher maintenance schedule:

1.Every day before starting:

Check hydraulic oil level
Inspect belts for cracks or fraying
Look for loose bolts on crusher frame
Check for material buildup around moving parts

2.Every week:

Check hammerheads or jaw plates for wear
Inspect conveyor belt tracking
Grease all bearings
Tighten motor mount bolts

3.Every month:

Change hydraulic oil if dirty
Check screen decks for holes or wear
Inspect electrical connections
Test emergency stop

Crusher wear parts replacement intervals:

Part	Normal life	Replace when
Hammerheads	200-300 hours	Worn more than 50%
Jaw plates	300-500 hours	Worn down to the mounting surface
Conveyor belt	1-2 years	Cracks or frayed edges
Hydraulic oil	500 hours	Dirty or smells burnt

Jaw plate wear happens faster on hard rock like granite. Softer rock like limestone wears plates slower. Adjust replacement intervals based on your material.

Common Operating Mistakes

These mistakes cause mobile crusher machine problems. Avoid them.

Feeding oversized material – A 300mm rock does not fit into a 200mm feed opening. It jams every time. Measure your material before feeding.

Crusher running empty – Running the crusher without material wears out bearings and wastes fuel. Stop the machine when not feeding.

Feeding too fast – The crusher cannot process material fast enough. Material piles up. Jams happen. Feed at a steady rate the machine can handle.

Ignoring belt tension adjustment – A loose belt slips. A tight belt wears bearings. Check belt tension every week.

Skipping regular lubrication – Bearings fail without grease. Hydraulic pumps fail without clean oil. Follow the schedule.

Quick Fault Diagnosis Table

Symptom	Likely Cause	What to Do
No material coming out	Feeder jam, crusher jam	Stop. Clear jam. Check feed size
Machine shakes badly	Worn hammerheads, loose bolts	Replace wear parts. Tighten bolts
Material too big	Worn hammerheads, wrong screen gap	Replace wear parts. Adjust gap
Belt runs off center	Uneven tension, material off center	Adjust tracking roller. Center feed
Low production	Worn parts, wrong feed rate	Replace wear parts. Adjust feed
Strange noise from crusher	Rock jam, broken part	Stop immediately. Inspect inside

When to Call a Technician?

Some mobile crusher troubleshooting is DIY. Some is not.

Fix yourself:

Adjust belt tracking
Replace worn hammerheads
Tighten loose bolts
Clean jams
Adjust discharge size

Call a technician:

Main bearing makes grinding noise
Hydraulic pump fails
Engine won’t start after basic checks
Frame has cracks
Electrical control problems

Do not run a mobile stone crusher plant with main bearing damage. The repair cost doubles if you keep running.

Need Help with Mobile Crushing Plant Problems?

YG Machinery provides spare parts and technical support for mobile crusher machines. Tell us your fault symptom. We will help you diagnose and find the right replacement part.

Get back to crushing faster.