CONVEYOR 01

GENERAL INDUSTRIAL
BELT CONVEYOR

Planetary gear specification: 2-stage, 20CrMnTi carburized, DIN 6–7, ratio 15:1–80:1, power 22–500 kW, matched planet pitch ±5 μm, floating sun, ISO 6336 rated life 20,000 hours. General industrial belt conveyors (manufacturing plant material transport, assembly line conveyors, warehouse sortation systems, aggregate quarry conveyors) represent the broadest category of conveyor planetary gear application by installed unit count. The 2-stage planetary gearbox in the 22–200 kW range is the workhorse product — compact, high-efficiency, and available in either shaft-mounted or foot-mounted configurations for the two standard conveyor drive head arrangements. The shaft-mounted configuration (a hollow-bore gearbox that slides directly onto the conveyor head drum shaft and is torque-arm restrained against rotation) is the most popular for new conveyor installations because it eliminates the flexible coupling, motor base, and alignment procedure required for foot-mounted installations. Korea Ever-Power 2-stage planetary gear sets for general industrial conveyors are supplied as matched complete stage kits — sun gear, 3 planet gears (pitch-matched), ring gear (internal), and planet carrier — for installation into new or refurbished conveyor drive gearbox housings. Gear oil: ISO VG 220 synthetic gear oil standard for conveyor drive planetary gearboxes at ambient temperatures above −15°C.

CONVEYOR 02

UNDERGROUND MINE
BELT CONVEYOR

Planetary gear specification: 2–3 stage, 20CrMnTi carburized, DIN 6 (profile ground), ratio 25:1–200:1, power 200 kW–2 MW, matched planet pitch ±3 μm, floating sun with load sharing measurement certificate, ISO 6336 rated life 40,000 hours, high-shock service factor KA = 1.5. Underground mine belt conveyors (coal, hard rock mining) operate in the most severe environment of any conveyor application — high humidity (90–100% RH), temperature variation from surface ambient to 30–40°C underground, coal dust or rock dust contamination, and the consequenceof an unplanned conveyor stop shutting down production from an entire mine section. The planetary gear set in an underground mine conveyor drive must sustain the conveyor’s starting torque (which can be 2–3× rated for long belt conveyors loaded with material at start) and the belt tension shock loads from splices passing the drive drum, while operating in the sealed housing of the conveyor drive unit for 40,000+ hours between planned maintenance overhauls. Korea Ever-Power mine conveyor planetary gear sets are designed with an additional shock service factor KA = 1.5 applied above the ISO 6336 working service factor to account for the non-quantifiable impact loads from belt splices and the full-load starting torque cycles accumulated over 40,000 hours of mine operation.

CONVEYOR 03

OVERLAND MINING
CONVEYOR

Planetary gear specification: 3-stage planetary (or 2-stage planetary + 1-stage helical), 20CrMnTi carburized, DIN 5–6, ratio 50:1–200:1, power 2–5 MW per drive head, 3–4 planet gears per stage for enhanced load sharing, ISO 6336 fatigue-based design life 60,000 hours, hydraulic soft start or CST (fluid coupling with soft start) to limit starting torque at the planetary gearbox. Overland mining belt conveyors — the multi-kilometre conveyor systems that transport iron ore, coal, copper, or aggregate from the mine to the port or processing plant — represent the highest-power, longest-running conveyor application for planetary gearboxes. The planetary drive on an overland mine conveyor is subject to constraints that drive unique engineering requirements: the gearbox must fit within the physical envelope of the conveyor drive head structure (often constrained to 3–4 metres width to maintain structural headroom requirements); the starting torque must be controlled to prevent belt slip and belt damage, which requires soft-start devices (fluid couplings, CST, or controlled starting devices) between the motor and the gearbox; and the load sharing among 3–4 planets per stage must be tightly controlled to prevent the catastrophic planet gear fatigue failures that have shut down entire mine operations for weeks while replacement gearboxes were manufactured and installed. Korea Ever-Power overland conveyor planetary gear sets use 4 planets per stage (not 3) for the highest-power applications — the 4-planet arrangement reduces the tooth load per planet by 25% compared to 3-planet, extending the gear fatigue life proportionally and providing a significant reserve against the load sharing inequality that inevitably exists in multi-planet designs.

Our 315 kW quarry conveyor planetary gearbox failed — one planet gear has a fractured tooth at the root. The gearbox is only 3 years old. What caused this and how do we prevent recurrence?

Planet gear tooth root fracture at 3 years in a 315 kW quarry conveyor drive is a bending fatigue failure — the tooth root has been loaded beyond its endurance limit for the number of cycles accumulated (315 kW × 3 years × 6,000 hours/year at typical quarry operation gives approximately 10⁸ planet gear tooth load cycles — at the edge of the endurance limit range for many carburized gear designs). Root causes in order of probability: (1) Overload from quarry conveyor starting: quarry belt conveyors are often started loaded (material on the belt from the previous production shift), which produces a starting torque of 2.5–3.5× rated. If the original gearbox was sized for an unloaded start (KS = 1.5) but is regularly started loaded (KS = 2.5–3.0), the planet gear tooth root has been experiencing 2–3× its designed stress at each start — accumulating fatigue damage at a rate 8–27× faster than designed. (2) Planet gear load sharing imbalance: if the fractured planet was consistently carrying more than its share of the total tangential force (due to pitch error or planet pin hole position error), its root stress was higher than the average planet stress assumed in the design. Inspection: after removing all three planet gears, measure the tooth thickness of each on a calibrated gear tooth vernier caliper and compare — if the fractured planet’s tooth is measurably thinner than the other two (from wear), it was carrying more load. Correction: specify Korea Ever-Power replacement planet gears with matched pitch (±3 μm batch selection) and confirm the conveyor soft-start device is correctly rated for loaded belt starting. (3) Insufficient carburized case depth: if the planet gear was manufactured with effective case depth below the minimum for the applied tooth root stress, the subsurface transition zone hardness is too low to sustain the cyclic bending stress — the fatigue crack initiates below the case-core interface rather than at the surface. Korea Ever-Power can analyse the fracture surface of the failed planet gear (request the returned part for metallurgical examination) to confirm which failure mechanism occurred and provide a root cause analysis report.

How do we identify the correct replacement planetary gear set for a conveyor gearbox when the gearbox nameplate has been damaged and the OEM model number is unknown?

Identifying a conveyor planetary gearbox model without the nameplate requires a systematic approach using the available physical measurements: (1) Measure the gearbox external dimensions: the overall length (input to output shaft), the housing flange OD or mounting bolt circle diameter, and the output shaft bore diameter. Korea Ever-Power maintains a database of external dimensions for all major conveyor gearbox OEM models (Sumitomo, Brevini/Rexnord, SEW, Flender, Dodge/Rexnord) — cross-referencing the external dimensions alone narrows the model to 3–5 candidates in most cases. (2) Count the ring gear teeth through the gearbox inspection port (or by rotation counting): rotate the output shaft by hand and count the input shaft revolutions for each full output revolution — this gives the exact overall ratio. From the ratio and the likely number of stages (a 2-stage box for ratios 15:1–100:1), Korea Ever-Power can calculate the possible sun/planet/ring tooth count combinations and identify the most likely stage ratios. (3) Measure the gearbox oil fill volume: the oil capacity (stamped on the name plate or stated in the manual) is closely linked to the internal housing volume, which is determined by the gear size and stage arrangement. This provides an independent cross-check. (4) Photograph the gear internals through the inspection port or after partial disassembly: module, tooth count, and quality can be estimated from close-up photos of the sun and planet gear surfaces. Korea Ever-Power’s application engineering team provides a free model identification service — submit the external dimensions, ratio measurement, oil volume, and any photographs, and Korea Ever-Power will identify the most likely OEM model and quote the matched replacement gear set within 48 hours.

What is the recommended oil change interval for conveyor planetary gearboxes, and how do oil analysis results indicate that an early oil change is needed?

Conveyor planetary gearbox oil change intervals depend on the oil type and the operating conditions: Standard intervals per ISO/TR 14179-2: mineral gear oil: 3,000–5,000 hours or 12–18 months (whichever is sooner) for ambient temperatures below 50°C. PAO synthetic gear oil: 8,000–12,000 hours or 24–36 months. For mine conveyor applications where ambient temperatures may exceed 40°C at the gearbox surface: reduce intervals by 30–40% (mineral oil: 2,000–3,000 hours; PAO: 5,000–8,000 hours). Oil analysis triggers for early change: Korea Ever-Power recommends oil analysis at 50% of the scheduled change interval to confirm the oil condition before the full interval has elapsed. Parameters indicating early oil change needed: (a) Viscosity deviation above ±15% from the original ISO VG grade — viscosity reduction indicates shear thinning of VI improver additives; viscosity increase indicates oxidation or contamination. (b) Water content above 0.1% by weight (Karl Fischer method) — water in planetary gear oil causes severe corrosion of the precision planet bearing elements within weeks. (c) Particle count above ISO 4406 cleanliness class 18/16/13 for the oil system — ferrous particle content (measured by the ICP atomic emission spectrum, Fe concentration above 50 ppm per 8,000 hours) indicates abnormal wear in the planetary stage gears or bearings. (d) TAN (Total Acid Number) above 2 mg KOH/g from the new oil baseline — indicates oil oxidation leading to additive depletion and acidic attack of copper-containing bearing alloys. Korea Ever-Power provides an oil analysis recommendation protocol for conveyor planetary gearboxes as part of the gear set supply documentation — giving the maintenance team the specific parameter limits and sampling intervals for the planetary gearbox model and operating conditions.

Spur Gears

M5–M16 · conveyor drum · heavy duty

Helical Gears

Conveyor gearbox · double-helical · mill

ベベルギア

Right-angle takeoff · conveyor branch

Worm Gears

Self-locking · slow conveyor · low power

Ring Gears

Planetary internal ring · conveyor drive

Planetary Gears

2–3 stage · 5 kW–5 MW · conveyor kit

Plastic Gears

Sensor · limit switch · light conveyor