Loader-fed ground hoppers — bridging, damaged grids and engulfment
Symptom
The ground hopper bridges with wet or frozen sand, grid bars are bent or missing, material spills at the tipping point, or the feeder belt is cut.
Likely causes
- Wet or frozen sand, a grid that is too fine, or a vibrator that does not work.
- Bucket impacts bending or breaking grid bars.
- Bucket wider than the hopper, no side plates, or tipping too fast.
- Large stones dropping from height onto a feeder belt with no impact support.
Most likely and cheapest to check first.
Checks
- Daily - grid intact, wheel stops and ramp edges in place, nobody walking on the ramp.
- Weekly - liners, dividing walls, gates, vibrators, tunnel lighting and drainage.
- Check that the grid openings are too small for a person to fall through.
Fix
- Repair damaged grid bars the same day.
- Cover stockpiles, improve drainage, heat in very cold climates; repair the vibrator.
- Fit side plates; train loader drivers to tip slowly.
- Fit an impact bed under the hopper.
Stop the equipment if
Anyone needs to enter the hopper. Lock out the feeder and belt, park the loader with keys removed, and clear from above first.
Parts you may need
Nobody enters a hopper in normal operation
Investigations show the same patterns again and again - people entering a hopper to free a hang-up, climbing on a loader bucket to reach it, or being in the hopper when the belt below starts. In one case a worker wearing a harness was still buried; the lifeline was buried too.
DANGERNever climb on a loader bucket or tyre, never prop a grizzly with timber, and keep people off the feed ramp. One person is in charge of starting belts, and radio messages are confirmed before any start.
FIELD TIPSet the grid size to the loader, not to the stone. It must stop a person falling in while letting aggregate through.
⚠ Every check inside a machine starts with full lockout. Safety disclaimer