Double Helical Gears For Agricultural Machinery – 40Cr, HRC

Double helical gears for agricultural machinery combine two helical gear sets of opposite hand side by side on a common gear body, so their individual axial thrust forces cancel each other. The result is a gear that delivers the smooth, quiet, high-load-capacity engagement of a helical gear without generating any net axial force on the shaft bearings. In agricultural power trains — combine harvester drives, tractor PTO gearboxes, grain auger drives, and crop processing power trains — the elimination of axial thrust simplifies bearing selection and reduces housing stress at the locations where agricultural equipment is most vulnerable to damage from field vibration and shock.

Korea Ever-Power produces these gears in 42CrMo alloy steel — the chromium-molybdenum grade that provides the combination of through-hardenability and toughness needed for the induction hardening process used to achieve 40–45 HRC surface hardness on agricultural gear teeth. 42CrMo corresponds to ISO 42CrMo4, ASTM 4140, JIS SCM440, and DIN 42CrMo4 — an internationally recognised grade with well-understood heat treatment response and wide procurement availability. Custom-made to customer drawings or samples using AutoCAD and SolidWorks-based gear design, to gear accuracy grades 8–10.

Combine Harvester Drives

Header drive gearboxes, threshing drum drives, and straw walker drives in combine harvesters. These drives encounter shock loads each time the machine enters a new section of crop, and vibration from uneven field surfaces — conditions that favour double helical gears for their thrust-free operation and smooth load transfer.

Tractor PTO Gearboxes

Power take-off (PTO) gearboxes and reduction stages in large agricultural tractors where the shaft space is constrained and axial thrust from single helical gears would require additional thrust bearing provision. Double helical gears allow the PTO gearbox to be more compact at the same output torque rating.

Grain Auger and Conveyor Drives

Grain auger drives, grain elevator boot drives, and crop conveyor reduction gearboxes in grain handling equipment. These drives run continuously during harvest season and must be reliable with minimal maintenance — the sealed, thrust-free operation of double helical gears suits this duty.

Motor and Electric Vehicle Drives

Electric motor reduction stages, electric car transmission gears, and motorcycle gearbox stages where the compact design and zero-thrust advantage of double helical gears is combined with the high efficiency required in electrified drivetrains. 42CrMo induction-hardened to 40–45 HRC at grades 8–10 is the standard specification for these drives.

Marine Auxiliary Drives

Small marine gearbox stages and auxiliary equipment drives on workboats, fishing vessels, and small commercial vessels where the zero-thrust property simplifies housing design in space-constrained engine room arrangements and where 42CrMo's corrosion resistance with appropriate surface treatment is adequate for sealed marine applications.

Ball Mill Drives

Custom transmission double helical gear sets for ball mill main drives as shown in the Custom Transmission configuration above. Ball mill drives require forged 42CrMo with gear milling — the same material and process sequence as the agricultural series, scaled to the larger module sizes used in mineral processing ball mills.

What quality certifications do these gears carry?

Korea Ever-Power holds CE, ISO, SGS, TUV, and SONCAP certifications for these products. These certifications cover the quality management system, product testing, and export compliance requirements for the primary export markets for agricultural machinery gears — Europe (CE), international quality standard (ISO), general product safety testing (SGS), German technical inspection (TUV), and West African conformity assessment (SONCAP). If your market or OEM programme requires a specific certification not listed, contact our team to discuss the available options.

What is the standard delivery time and can products be customised?

Standard delivery is approximately 30 days. Customised products are delivered per negotiation with the client — lead time depends on the gear size, module, and whether new tooling is required for non-standard configurations. Logo customisation and OEM branding are available. Products can be made to customer drawings or samples; Korea Ever-Power will verify the geometry using AutoCAD and SolidWorks before production begins to confirm correct meshing with the mating gear.

How is the product protected during long-distance sea freight?

Products are film-wrapped to protect against moisture and surface contamination. For sea freight shipments, steel wire is used to fix the gear to the container structure, preventing the gear from moving during transit vibration and ship motion. This prevents the impact damage that can occur when heavy gears are not fixed in a container. For precision-ground gears, additional protective packaging is applied to protect tooth flanks from fretting during transit.

What payment terms are accepted?

Two payment arrangements are available: 100% T/T (telegraphic transfer) before shipment, or 30% deposit by T/T with the balance paid by L/C (letter of credit). For new customers, the 100% T/T arrangement is standard. L/C arrangements are available for established customers with confirmed order programmes. Contact our team to discuss the appropriate payment arrangement for your purchasing process.

Can these gears be produced in other materials besides 42CrMo?

Yes — all materials in the steel grade cross-reference table above are available, plus other alloy steels per customer specification. The standard agricultural machinery configuration uses 42CrMo with induction hardening for 40–45 HRC. If a higher surface hardness is required (for example, 58–62 HRC for higher-load ball mill applications), carburising in 20CrMnTi, 20CrNiMo, or 17CrNiMo6 is available. If a softer, more field-repairable specification is preferred, 45# or 40Cr with through-hardening is available. Contact our team with your hardness requirement and the application's duty cycle and we will recommend the appropriate material and heat treatment combination.

"We manufacture combine harvester header drives and replaced single helical gears with double helical gears from Korea Ever-Power in 42CrMo at grade 9. The bearing temperature in the header gearbox dropped by 8°C after eliminating the axial thrust load on the shaft bearing. We are now specifying double helical gears as the standard configuration on all new header drive designs."

Kim Byeong-jun  |  Drivetrain Engineer, Jeonbuk Agricultural Machinery Manufacturing  ·  Q2 2026

"We supply grain auger drives for large-scale grain handling facilities and order 42CrMo double helical gears at grade 9 from Korea Ever-Power. Delivery was within 30 days on both initial and repeat orders. CE and ISO certificates were provided with the first order and are accepted by our downstream customers without further audit."

Park Jeong-min  |  Procurement Manager, Gyeonggi Grain Handling Systems  ·  Q4 2025

"We needed a custom double helical gear to replace an obsolete OEM part in a ball mill gearbox — no drawing available. Korea Ever-Power measured the worn gear, calculated the geometry using SolidWorks, verified against the mating gear, and produced the replacement in 42CrMo with gear milling. The replacement gear meshed correctly at first installation and the ball mill has operated without interruption since."

Lee Cheol-su  |  Maintenance Manager, Daejeon Mineral Processing Plant  ·  Q1 2026

"We design electric vehicle reduction units for agricultural electric transport vehicles and specified 42CrMo induction-hardened double helical gears at grade 9 from Korea Ever-Power. The SGS test certificate meets our downstream OEM customer's incoming inspection requirement. Three production batches delivered within the 30-day standard lead time; dimensional consistency across all batches confirmed at incoming inspection."

Choi Min-seok  |  Product Development Engineer, Incheon Electric Vehicle Drives  ·  Q3 2025

"We export agricultural gearboxes to West Africa and require SONCAP certification for all gear components. Korea Ever-Power's agricultural double helical gears are supplied with SONCAP certification that meets the Nigerian Standards Organisation requirement without any additional paperwork from our side. The L/C payment arrangement was straightforward to set up for our annual purchasing programme."

Yoon Tae-sik  |  Export Manager, Busan Agricultural Equipment Export Co.  ·  Q2 2025