Always Specify Helical

• ✓ Noise spec below 72 dB(A) at 1 m from gearbox
• ✓ PLV above 6 m/s at any gear stage
• ✓ Indoor logistics centre with operator noise regulations
• ✓ Food factory conveyor with staff noise exposure limit
• ✓ Hospital / pharmaceutical distribution conveyor
• ✓ Gearbox volume constraint requiring higher load density

Spur Gear Is Correct Choice

• ✓ Outdoor, mining, or aggregate conveyor (ambient >80 dB(A))
• ✓ PLV below 5 m/s throughout all stages
• ✓ Open-gear large-diameter conveyor head drive
• ✓ Budget-constrained replacement with no noise spec
• ✓ Existing spur gearbox housing (re-use housing)
• ✓ No axial thrust bearing capacity available in conveyor shaft

Additional Design Consideration

Helical gear conveyor drives require angular contact or tapered roller bearings on the conveyor head shaft to absorb the axial thrust generated by the helix angle. Before specifying helical gears for a conveyor that currently uses spur gears, confirm the conveyor head shaft bearings are rated for the combined radial and axial load. At helix angle 20°, axial thrust = tangential force × tan(20°) = 0.36 × F_t — significant on large high-load conveyors.

APP 01

INDOOR LOGISTICS
CONVEYOR

Helical gear specification: M4–M8, 20CrMnTi or 42CrMo4, helix angle 15°–20°, DIN 7–8, enclosed gearbox with angular contact bearings. Automated warehouse sortation conveyors, e-commerce fulfilment centre belt drives, and postal facility conveyor lines must operate below the noise limit set by local occupational health regulations (typically 80–85 dB(A) at operator workstations). Helical gear conveyor gearboxes achieving 72–75 dB(A) are routinely specified for these applications, where equivalent spur gear gearboxes would measure 80–83 dB(A). Service factor 1.25 for smooth continuous belt conveyor in climate-controlled warehouse environment.

APP 02

FOOD PROCESSING
CONVEYOR

Helical gear specification: M3–M6, 316L stainless or 20CrMnTi sealed behind stainless housing, helix 15°–18°, NSF H1 lubricant, IP67 sealed for CIP washdown. Food processing conveyor helical gear drives carry the additional requirement of corrosion resistance to daily CIP cleaning with NaOH and hypochlorite solutions. Enclosed helical gearboxes in 316L stainless housing with EPDM shaft seals and NSF H1 food-grade PAO lubricant are standard for meat processing, dairy, and beverage conveyor drives. The helical gear noise reduction is particularly important in food processing environments where operating personnel spend entire shifts within 2–3 m of conveyor gearboxes. Noise reduction from 82 dB(A) spur to 74 dB(A) helical reduces daily noise exposure dose by approximately 40% at the operator position.

APP 03

HIGH-SPEED
CONVEYOR DRIVE

Helical gear specification: M4–M8, 20CrMnTi case carburized, helix 18°–22°, DIN 5–6 ground, PLV 6–18 m/s. Airport baggage handling system (BHS) conveyors, package sorting conveyors, and high-speed parcel conveyors operate belt speeds of 2–5 m/s — producing PLV of 6–15 m/s in the conveyor gearbox input stage pinion at 1,450 RPM motor speed. At these PLVs, the dynamic factor K_v in the gear load calculation rises significantly unless the gear quality class is DIN 6 or better. Ground DIN 6 helical gears are mandatory for high-speed conveyor gearboxes above 8 m/s PLV to maintain bearing life and control dynamic mesh forces within the gearbox housing fatigue limit.

APP 04

POWER CONVEYOR
ABOVE 75 kW

Helical gear specification: M8–M12, 20CrMnTi or 18CrNiMo7, helix 15°–20°, DIN 6, two or three stage. For enclosed conveyor gearboxes above 75 kW where the gearbox housing size is constrained by the installation envelope, the 15–30% higher power density of helical gears vs spur gears allows the required power to be transmitted in a smaller housing. Cement plant raw meal conveyor gearboxes, steel mill scale conveyor drives, and mining plant concentrate conveyor gearboxes above 75 kW commonly use helical gear stages to achieve the compact housing dimensions that the plant layout requires. Korea Ever-Power supplies both replacement helical gear sets and complete helical gearbox stages for conveyor OEM and service applications above 75 kW.

I need to replace a spur gear conveyor drive with a quieter option. Can I simply substitute helical gears into the existing housing?

A direct spur-to-helical substitution in an existing housing requires three checks: (1) Bearing axial thrust capacity: helical gears generate axial thrust that the original spur gear housing bearings were not designed to carry. The shaft bearings must be upgraded from deep-groove ball bearings (radial only) to angular contact or tapered roller bearings capable of carrying the thrust F_a = F_t × tan(ψ). (2) Centre distance compatibility: helical gears in the same module as the replaced spur gears can be used at the same centre distance — the normal module equals the transverse module ÷ cos(ψ), but the standard centre distance formula still applies to the transverse plane, so helical and spur gears of the same transverse module and tooth count have the same pitch diameter. (3) Axial tooth width: helical gears need face width b ≥ (π × module) ÷ sin(ψ) to achieve overlap ratio >1.0 — ensure the available housing face width allows this. If bearing replacement is not practical, the alternative is a double-helical (herringbone) gear replacement that cancels axial thrust — Korea Ever-Power supplies double-helical replacement sets for large conveyor head gearboxes on request.

What helix angle should I specify for a conveyor helical gearbox to best balance noise reduction and axial thrust?

The standard industrial conveyor helical gearbox uses a helix angle of 15°–20° — this achieves 6–8 dB(A) noise reduction vs spur gears while limiting axial thrust to 0.27–0.36 × the tangential force, manageable with angular contact ball bearings in the standard IEC frame size range. For applications where maximum noise reduction is required and the bearing arrangement can accommodate higher thrust (or where double-helical design is used): specify 22°–28° helix angle for an additional 1–2 dB(A) noise reduction. For applications where the existing conveyor shaft bearings are deep-groove ball bearings that cannot be upgraded: limit helix angle to 8°–12° — this gives 3–4 dB(A) noise reduction with minimal axial thrust (tan(10°) = 0.18 × F_t), manageable by standard deep-groove bearings with adequate axial capacity. Korea Ever-Power can calculate the axial thrust, bearing selection, and noise reduction estimate for your specific conveyor power and helix angle — contact with motor kW, speed, and the bearing type currently installed on the conveyor head shaft.

What is the lead time for replacement helical gears for a standard brand-name enclosed conveyor gearbox?

Korea Ever-Power supplies replacement helical gear sets for standard enclosed conveyor gearboxes from all major brands (SEW-Eurodrive, Flender, Nord Drivesystems, Rossi, Bonfiglioli, Siemens, and Chinese standard reduction gear series). Lead time varies by gear size and material: Small conveyor helical gears (M4–M6, OD below 150 mm, 20CrMnTi or 42CrMo4, DIN 7–8, hobbed): 10–18 days from drawing confirmation. Medium conveyor helical gears (M6–M10, OD 150–350 mm, 20CrMnTi case carburized, DIN 6–7, ground): 20–32 days. Large conveyor helical gears (M10–M12, OD above 350 mm): 30–45 days. For emergency conveyor breakdown orders, contact Korea Ever-Power directly with the gearbox model number or the gear measurements (module, tooth count, helix angle, OD, bore, face width, helix hand) and the production restart deadline — priority processing can be assessed.

Spur Gears

M1–M20 · C45, 20CrMnTi, 316L

Helical Gears

Low noise · high contact ratio · gearbox

Engrenages coniques

Right-angle drives · straight & spiral

Worm Gears

High ratio · self-locking · valve, hoist

Ring Gears

Internal · planetary · wind, excavator

Planetary Gears

Compact · high torque density · servo, EV

Plastic Gears

POM · MC Nylon · FDA · self-lubricating