Worm Gearbox for Belt Conveyor Systems
Belt conveyors are the circulatory system of Australia’s mining and bulk-materials industry, moving millions of tonnes of coal, iron ore, grain, and mineral aggregate every year. Behind every reliably running conveyor is a precisely selected drive unit — and the snäckväxel has earned its dominant position through a combination of self-locking geometry, compact right-angle output, and robust high-torque delivery.
The self-locking characteristic is particularly critical on inclined conveyors: when power is removed, the irreversible worm geometry prevents the loaded belt from reversing under gravity. This eliminates the need for a separate backstop or motorised brake on many installations, simplifying the mechanical design and reducing maintenance exposure.
Standard NMRV and NRV series aluminium or ductile-iron worm gearboxes are available in frames from 025 to 150, providing output torques from 2.6 N·m up to 4,200 N·m and reduction ratios from 5:1 to 100:1 in a single compact stage. Two-stage tandem configurations extend this to 3,600:1.
Branschapplikationer och användningsfall
In a typical belt conveyor drive arrangement, the snäckväxel sits between the electric motor and the conveyor head drum. Key application points include:
- Head-end drive units on horizontal conveyors — steady torque, self-lock on stop
- Inclined conveyor drives — self-locking prevents roll-back under loaded belt weight
- Take-up winch drives — precise low-speed tension control on counterweight systems
- Belt weigh feeder drives — accurate, vibration-free low-speed output
Materials: Worm shaft in surface-hardened alloy steel 20CrMnTi (HRC 58–62). Worm wheel in centrifugally cast phosphor bronze. Housing in ductile iron GGG40 with IP65 dust-and-jet-water sealing.
Working principle: The helical worm thread engages the bronze wheel teeth at 90°. Back-driving from the wheel side is geometrically prevented when the lead angle is below the friction angle — this is the self-locking mechanism at the heart of safe conveyor operation.
Tekniska specifikationer och urvalsguide
Använd tabellen nedan för att identifiera lämplig modell. Viktiga parametrar inkluderar utväxling, utgående vridmoment, axeldimensioner och husmaterial. Använd alltid rätt Servicefaktor (SF) för din arbetscykel.
| Parameter | Typiskt intervall/värde | Urvalsanteckningar |
|---|---|---|
| Förhållande | 5:1 – 100:1 (single-stage) | Two-stage tandem available up to 3,600:1 |
| Utgående vridmoment | 2.6 – 4,200 N·m | Dependent on frame size 025–150 |
| Input Shaft Diameter | 11 – 42 mm | IEC 60034 standard flange sizes B5/B14 |
| Output Shaft Diameter | 14 – 50 mm (solid) | Hollow bore available from frame 030 up |
| Höljets material | Aluminium alloy / Ductile iron GGG40 | Stainless steel 316 available on request |
| Mounting Type | Foot / Flange / Shaft-mounted | All standard orientations F1–F8 |
| Skyddsklass | IP65 standard; IP66 / IP69K optional | Specify at order for outdoor / washdown duty |
► Servicefaktor (SF): Uniform load SF=1.0 | Moderate shock SF=1.25–1.5 | Heavy shock / 24 h continuous SF=1.75–2.0
► Omgivningstemperatur: Standard units rated –10°C to +40°C. Australian high-ambient sites (>45°C) require high-temperature lubricant and 15% thermal derating.
NMRV/NRV-seriens snäckväxel
Available in frame sizes 025 through 150. Single-stage reduction ratios 5:1 to 100:1. Output torque up to 4,200 N·m. Aluminium or ductile iron housing. IEC B5/B14 motor flange. IP65 standard, IP66/IP67 optional. Synthetic or mineral oil lubrication.
Efterlevnad och kvalitetsstandarder
Certifierat kvalitetsledningssystem. Varje enhet tillverkas och inspekteras enligt ett dokumenterat kvalitetsledningssystem med fullständig spårbarhet.
CE-märkt enligt EU:s maskindirektiv. Brett accepterad i australiska och nyzeeländska ingenjörsprojekt.
IEC-standardfläns- och axeldimensioner. Direktmonterad kompatibilitet med alla större motormärken.
Dammtät och högtrycksvattenbeständig. Standarden för utomhusinstallationer i Australien.
Fallstudier
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Case Study 1 — Open-Cut Coal Mine, Hunter Valley NSW
Inclined Belt Conveyor
Kundens smärtpunkt: A coal mine was experiencing rollback on a 15° inclined conveyor each time the belt tripped under overload. The mechanical backstop failed twice in six months, causing 18 hours of downtime per incident.
Lösning: NMRV-110 worm gearboxes (ratio 60:1, ductile iron, IP65) were installed on both drive stations. The inherent self-locking eliminated the need for the external backstop entirely.
Resultat: Zero rollback incidents over 14 months. Annual maintenance cost reduced by 35%. The mine standardised the same model across three further inclined conveyors on site.
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Case Study 2 — Mineral Processing Plant, Western Australia
Horizontal Ore Conveyor
Kundens smärtpunkt: A WA iron ore processor needed to replace an ageing helical gearbox generating 74 dB(A) of gear noise, with oil changes every 1,500 hours due to worn lip seals.
Lösning: NRV series worm gearbox (ratio 40:1, 1,800 N·m) with upgraded FKM double-lip seals and synthetic PAO gear oil.
Resultat: Operating noise reduced to 61 dB(A). Oil change interval extended to 5,000 hours. Zero seal leaks during two 12-month inspection cycles.
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Case Study 3 — Grain Handling Terminal, Port of Geraldton WA
Belt Weigh Feeder
Kundens smärtpunkt: A grain terminal’s weigh feeder was overspeeding by up to 8%, causing inaccurate throughput measurement and regulatory compliance issues.
Lösning: NMRV-063 worm gearboxes (ratio 80:1) replaced the helical-bevel units. Smooth, low-backlash output eliminated speed hunting corrupting the load cell signal.
Resultat: Throughput accuracy improved to within 0.3% of certified scale. Port authority compliance reinstated within one week.
NMRV / NRV series worm gearboxes — frame sizes 025 to 150, manufactured to ISO 9001:2015
Varför välja oss?
20+ års tillverkning
ISO-certifierad produktion sedan 2003. Snäckväxlar levereras till fler än 60 länder.
Teknisk fjärrsupport
Videosamtaldiagnostik över australiska tidszoner. Snabb respons utan besök på plats.
OEM/ODM-anpassning
Icke-standardiserade axlar, ihåligt hål, specialanpassade flänsar och utväxlingar. Fullständig ritning tillgänglig.
Fabriksdirektvärde
Ingen distributörsmarginal. Transparent volymprissättning med betydande besparingar på återkommande beställningar.
Lager och snabb leverans
Standard NMRV/NRV-ramar finns i lager. Brådskande beställningar hanteras för expressfrakt.
Vanliga frågor
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