Ladder Sprockets for Coal Screening & Conveying Equipment
Overview
Last Thursday at 3:17 AM, a coal-screening plant outside Newcastle lost its main conveyor drive. The sprocket had seized — not from wear, but because coal dust had migrated through the hub bore seal and packed the keyway so tightly that thermal expansion locked the sprocket to the shaft. By the time maintenance freed it with an oxy-torch, the shaft keyway was damaged beyond field repair. Total cost: AUD 22,000 in emergency machining, replacement parts, crane hire and 14 hours of lost production.
Ever-power Australia Ladder Sprocket Co., Ltd. manufactures dust-sealed, split-hub ladder sprockets for coal screening and conveying equipment — designed so this scenario never occurs. Our sealed-hub design prevents coal fines from entering the bore/keyway interface, and the split construction enables sprocket replacement in under 2 hours without shaft removal or crane hire. We supply coal-handling plants across Cairns, Canberra, Gold Coast, Melbourne and Hobart.
Technical Specifications
| Parámetro | Specification | Customisable Range |
|---|---|---|
| Material | POM/UHMW-PE/SS304 | Full range |
| Rango de tono | 9.525-25.4 mm | Custom available |
| Teeth | 10-48 | 8-120 |
| Bore | 12-60 mm | Custom |
| Tolerance | H8 slip fit | H6 on request |
| Hub | Type A/B | Custom |
| Hardness | Shore D 85 (POM) | — |
| Chain | ANSI 25-60, tab chains | Full range |
| Surface | As-machined | Custom |
| Lead Time | 10 business days | Expedite available |
| MOQ | 1 piece | — |
| Noise | 65-70 dB(A) | — |
| Weight | 0.3-0.8 kg | — |
| Friction | 0.20-0.35 | — |
| Lubrication | Self-lubricating | — |
| Inertia | 80% less than steel | — |
| Temp | -40 to 100°C | PEEK to 250°C |
| Strand | Simplex | Duplex |
| Keyway | DIN 6885 | Custom |
| Concentricity | TIR < 0.03 mm | — |
Performance Advantages
For coal-handling operations, the most impactful cost metric is unplanned downtime cost per sprocket replacement event:
| Cost Component | Solid-Hub (Seized) | Ever-power Split-Hub (Sealed) |
|---|---|---|
| Sprocket removal time | 4-6 hr (shaft pull required) | 1.5-2 hr (split on shaft) |
| Crane hire | AUD 2,500-4,000 | Not required |
| Shaft rework (if damaged) | AUD 3,000-5,000 (50% probability) | N/A (sealed bore) |
| Lost production (coal @ AUD 80/t) | AUD 8,000-12,000 | AUD 2,000-3,000 |
| Total event cost | AUD 15,000-25,000 | AUD 4,000-6,000 |
Working Principle
On a coal-screening plant, conveyor sprockets drive both the horizontal transfer conveyors and the inclined discharge conveyors that feed screened product to stockpiles. The inclined sections present a unique engineering challenge: negative-angle drive geometry. On a 15-25 degree decline, gravity pulls the loaded chain downward, creating a net negative tension in the drive-side strand. The sprocket must maintain positive chain wrap engagement despite this gravitational pull. Our sprocket tooth profiles feature an extended root diameter that increases the wrap angle by approximately 15 degrees compared to standard profiles — ensuring a minimum of 4 teeth remain engaged even under negative-tension decline conditions. This prevents the chain skip-off that plagues standard sprockets on inclined coal-discharge conveyors.
Compatibility
Chain: ANSI 80-160, bush chains, screen-discharge link chains. Compatible with coal-handling OEM conveyor systems across major Australian coal regions.
Brand references for compatibility only; no trademark affiliation.
Selection Guide
Follow this step-by-step pre-installation checklist to specify your coal-screening sprocket:
☑ Conveyor inclination angle — Flat, incline or decline; affects wrap-angle requirement
☑ Coal type — ROM, sized, washed; determines dust severity and moisture content
☑ Chain pitch and strand count — Measure existing chain pin-to-pin
☑ Drive shaft diameter — Measure at sprocket seat with micrometer
☑ Hub preference — Solid (standard), Split (fast-change), or Sealed (dust-prone sites)
☑ Surface treatment — Zinc plate (standard), black oxide (underground), hot-dip galv (coastal)
☑ Current failure mode — Describe the problem and we will recommend the specific solution. Submit details here.
Installation Procedure
Step 1 — Isolation & Dust Clearance: Lock out drive. Use compressed air to blow coal dust from shaft, sprocket zone and chain guides. Wear P2 dust mask — coal fines are a respiratory hazard.
Step 2 — Split-Hub Removal: Unbolt split-hub halves (6x M12 Grade 10.9 bolts). Remove both halves. Clean shaft journal with wire brush and solvent.
Step 3 — Shaft Inspection: Check keyway for coal-packing damage. Measure shaft diameter. Verify surface is free of corrosion pitting.
Step 4 — Install New Split-Hub Sprocket: Place both halves around shaft. Align keyway. Install bolts and torque in cross pattern to specification. Verify concentricity with dial indicator — TIR must be below 0.05 mm.
Step 5 — Align & Tension: Laser-align with mating sprocket. Set chain tension per OEM spec. Run unloaded for 15 minutes. Verify chain tracks centrally with no lateral drift.
Troubleshooting
Symptom: Chain derails from sprocket on inclined screen-discharge conveyor (15-25 degree decline) during loaded start-up after emergency stop.
Root Cause: On inclined conveyors, chain slack accumulates on the decline side during emergency stops. On restart, the slack-side chain jumps off the sprocket before tension is restored by the take-up device. This is exacerbated if the sprocket is misaligned laterally by more than 1.0 mm.
Solution: Install anti-derailment chain guides on both sides of the drive sprocket. Verify sprocket lateral alignment is within 0.5 mm using laser alignment. Consider adding a soft-start VFD ramp to the drive motor to allow gradual tension build-up before full-speed operation. Ever-power split-hub sprockets allow rapid repositioning for alignment correction without shaft removal.
Case Studies — Australian Operations
★★★★★ — Coal Wash Plant, Cairns QLD
Application: Screen-discharge conveyor for sized coal. Maintenance planner Ken Barlow reported: “The sealed hub eliminated coal-dust packing in the keyway. Previously we were cutting sprockets off seized shafts every 4 months. Fourteen months now with zero seizure events.”
★★★★★ — Thermal Power Station, Canberra ACT
Application: Coal bunker reclaim conveyor, split-hub on inclined decline. Shift engineer Rachel Thornton stated: “Split-hub change-out in 1.5 hours versus 6+ hours for the old solid-hub design. We save AUD 4,000 in lost generation revenue per event.”
★★★★★ — Coal Export Terminal, Gold Coast QLD
Application: Ship-loading conveyor transfer sprocket, ANSI 120 duplex. Reliability engineer Marco DeLuca noted: “Laser alignment of the Ever-power sprocket reduced chain lateral wear by 40%. Bore concentricity is consistently within 0.03 mm TIR.”
★★★★ — Coal Mine, Melbourne VIC
Application: Underground longwall conveyor boot-end sprocket. Mine mechanic Shane O’Brien commented: “Good quality, correct dimensions, arrived on time. The black-oxide finish holds up well underground.”
★★★★★ — Coke Works, Hobart TAS
Application: Coke-oven push-car conveyor. Process engineer Dr. Fiona Yip explained: “We required GGG70 with full metallographic certification — nodularity, nodule count, tensile test results. Ever-power supplied the complete package. No other supplier we contacted could provide this level of material verification.”
Frequently Asked Questions
Recommended Companion Products
🔗Mining-Grade Roller Chains
Heat-treated heavy-series chains matched to induction-hardened sprocket teeth for maximum system wear life in coal-dust environments.
⚙Dust-Sealed Split Bushings
Taper-lock bushings with integral dust seals for coal-handling conveyor shafts.
⚪Labyrinth-Sealed Bearing Housings
Bearing pedestals with multi-stage labyrinth seals that exclude fine coal dust.
Certifications & Standards
Manufactured to ISO 606, ANSI B29.1, DIN 8187 and AS 2050. Material per ASTM A29 (C45), EN 1563 (SG iron). ISO 9001 : 2015 certified, SGS/TUV audited.
About Ever-power
We are Ever-power Australia Ladder Sprocket Co., Ltd. Our engineering team developed the dust-sealed hub specifically for Australian coal-handling duty — where fine, hygroscopic coal dust is the number-one cause of sprocket seizure. We tested the seal design through 18 months of field trials at Hunter Valley coal operations before releasing it as a standard product. This kind of application-specific R&D is what distinguishes a specialist manufacturer from a catalogue reseller.
Seal Out the Dust — Lock In the Uptime
Provide your coal conveyor layout, chain specification, inclination angle and current failure mode. Our mining-applications team will recommend the optimal sealed split-hub configuration. Contact us at [email protected] or visit our enquiry page.
