After the drum, every ton of hot aggregate rides the elevator to the top of the tower and passes the vibrating screen. Both work at high temperature under constant load. Their condition affects output, gradation and safety.
Lock out the elevator and screen drives before inspection. Work at height needs fall protection.
Hot elevator
| Part | What to check | How often |
|---|---|---|
| Chain (or belt) | Elongation, tension, damaged links | Weekly; measure monthly |
| Buckets | Cracks, wear at lips, loose bolts | Weekly |
| Head and boot sprockets | Tooth wear, hooking | Monthly |
| Drive and backstop | Oil level, noise, backstop function | Weekly |
| Casing and inspection doors | Leaks, wear plates | Monthly |
| Boot | Spillage build-up | Daily |
Chain elongation is the key measurement. A stretched chain rides up the sprocket teeth, wears them, and can jump or break under load. Replace chain and sprockets together when both are worn.
Vibrating screen
| Part | What to check | How often |
|---|---|---|
| Screen meshes (each deck) | Holes, broken wires, blinding, tension | Weekly |
| Springs | Cracks, breakage, uneven height | Weekly |
| Exciter bearings | Temperature, noise, lubrication | Daily–weekly |
| Mounting bolts and frame | Tightness, cracks | Monthly |
| Dust cover and seals | Leaks to the baghouse duct | Monthly |
| Overflow chute | Clear path | Daily |
Holes in a mesh let oversize pass to a finer bin; blinded meshes push fines over into coarser bins. Either way, gradation drifts and hot bins overflow or run empty. Keep spare meshes for the deck that wears fastest.
Hot bins
- Check bin level indicators work
- Keep overflow chutes clear
- Look for wear at bin walls and gates
- Check gates for leakage into the aggregate scale
Signs that point to the elevator or screen
| Symptom | Possible cause |
|---|---|
| Hot bin overflowing | Screen deck worn or blinded; feed proportions off |
| Hot bin running empty | Screen blinding; feeder setting; elevator slipping |
| Gradation drifting | Mesh holes; blinding |
| Knocking from the tower | Loose bucket; chain jumping |
| Excessive vibration | Spring or bearing failure; loose bolts |
For how screening controls gradation, see vibrating screen and hot bins. Back to the maintenance checklist or order meshes and buckets.
