{"id":2048,"date":"2026-04-10T09:07:01","date_gmt":"2026-04-10T09:07:01","guid":{"rendered":"https:\/\/helicalcutgears.top\/?post_type=product&p=2048"},"modified":"2026-04-10T09:07:01","modified_gmt":"2026-04-10T09:07:01","slug":"heavy-machinery-double-helical-gear-cast-steel-soft-tooth-flank-qt-iso-grade-8-9","status":"publish","type":"product","link":"https:\/\/helicalcutgears.top\/th\/product\/heavy-machinery-double-helical-gear-cast-steel-soft-tooth-flank-qt-iso-grade-8-9\/","title":{"rendered":"\u0e40\u0e1f\u0e37\u0e2d\u0e07\u0e40\u0e01\u0e25\u0e35\u0e22\u0e27\u0e04\u0e39\u0e48\u0e2a\u0e33\u0e2b\u0e23\u0e31\u0e1a\u0e40\u0e04\u0e23\u0e37\u0e48\u0e2d\u0e07\u0e08\u0e31\u0e01\u0e23\u0e2b\u0e19\u0e31\u0e01 \u2014 \u0e40\u0e2b\u0e25\u0e47\u0e01\u0e2b\u0e25\u0e48\u0e2d\u0e41\u0e1a\u0e1a\u0e1f\u0e31\u0e19\u0e2d\u0e48\u0e2d\u0e19 QT \u0e40\u0e01\u0e23\u0e14 ISO 8\u20139"},"content":{"rendered":"
\n

Heavy Machinery Double Helical Gear \u2014 Overview<\/h2>\n

When a gear is large enough that the blank weight approaches or exceeds five tonnes, the forging route that is standard for small and medium industrial gears becomes impractical or prohibitively expensive. The largest gears in the world \u2014 ball mill ring gears three metres in diameter, cement mill main pinions with face widths of 700mm, ship propulsion gears transmitting 20,000+ kW \u2014 are manufactured from cast steel blanks, where the complexity of the part’s final shape can be incorporated into the mold rather than laboriously machined from a forged cylinder. Korea Ever-Power Worm Gear Co.,Ltd supplies heavy machinery double helical gears<\/strong> in custom cast steel grades, quenched and tempered to a soft tooth flank condition, hobbed to ISO grade 8\u20139 accuracy, for the most demanding large-scale industrial drive applications.<\/p>\n

\"\u0e40\u0e1f\u0e37\u0e2d\u0e07\u0e40\u0e01\u0e25\u0e35\u0e22\u0e27\u0e04\u0e39\u0e48\"<\/p>\n

The double helical (herringbone) tooth form is particularly well-suited to heavy machinery applications because it eliminates the axial thrust force that a single helical gear of equivalent size and helix angle would transmit to the shaft and bearings. For a large mill drive gear transmitting several megawatts, this axial force would be substantial \u2014 requiring large, expensive thrust bearings or roller-type spherical bearings at both ends of the gear shaft. The double helical configuration removes this requirement entirely, allowing simpler bearing arrangements in very large gearbox housings where bearing accessibility and replacement cost are significant lifecycle concerns. Korea Ever-Power’s heavy machinery double helical gears<\/strong> are custom-manufactured to each client’s drawing \u2014 module, tooth count, helical angle, pressure angle, face width, bore, and keyway dimensions are all specified by the customer. International steel grade cross-reference is supported for customers specifying materials in ASTM, DIN, JIS, or ISO standards.<\/p>\n

\u0e02\u0e49\u0e2d\u0e01\u0e33\u0e2b\u0e19\u0e14\u0e17\u0e32\u0e07\u0e40\u0e17\u0e04\u0e19\u0e34\u0e04<\/h2>\n

Product Specifications \u2014 Heavy Machinery Double Helical Gear<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\u0e1e\u0e32\u0e23\u0e32\u0e21\u0e34\u0e40\u0e15\u0e2d\u0e23\u0e4c<\/th>\n\u0e04\u0e48\u0e32<\/th>\n<\/tr>\n
\u0e1b\u0e23\u0e30\u0e40\u0e20\u0e17\u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c<\/td>\n\u0e40\u0e1f\u0e37\u0e2d\u0e07\u0e40\u0e01\u0e25\u0e35\u0e22\u0e27\u0e04\u0e39\u0e48 (\u0e40\u0e1f\u0e37\u0e2d\u0e07\u0e01\u0e49\u0e32\u0e07\u0e1b\u0e25\u0e32)<\/td>\n<\/tr>\n
\u0e27\u0e31\u0e2a\u0e14\u0e38<\/td>\nCast Steel (custom grade per drawing \u2014 ZG35CrMo, ZG42CrMo, ZG310-570, or equivalent)<\/td>\n<\/tr>\n
\u0e04\u0e27\u0e32\u0e21\u0e41\u0e02\u0e47\u0e07<\/td>\nSoft Tooth Surface (QT to specified HB range)<\/td>\n<\/tr>\n
\u0e01\u0e32\u0e23\u0e2d\u0e1a\u0e0a\u0e38\u0e1a\u0e14\u0e49\u0e27\u0e22\u0e04\u0e27\u0e32\u0e21\u0e23\u0e49\u0e2d\u0e19<\/td>\nQuenching and Tempering (through-hardened); surface hardness options available<\/td>\n<\/tr>\n
Gear Manufacturing<\/td>\nGear Hobbing (no grinding \u2014 as-hobbed finish)<\/td>\n<\/tr>\n
\u0e21\u0e38\u0e21\u0e41\u0e23\u0e07\u0e14\u0e31\u0e19<\/td>\n20\u00b0 (standard); custom angles available<\/td>\n<\/tr>\n
Helical Angle<\/td>\nCustom Made (specified per drawing)<\/td>\n<\/tr>\n
\u0e23\u0e30\u0e14\u0e31\u0e1a\u0e04\u0e27\u0e32\u0e21\u0e41\u0e21\u0e48\u0e19\u0e22\u0e33\u0e02\u0e2d\u0e07\u0e40\u0e01\u0e35\u0e22\u0e23\u0e4c<\/td>\nGrade 8\u20139 (ISO 1328)<\/td>\n<\/tr>\n
\u0e02\u0e2d\u0e1a\u0e40\u0e02\u0e15\u0e01\u0e32\u0e23\u0e43\u0e0a\u0e49\u0e07\u0e32\u0e19<\/td>\nBall mills, cement mills, ore processing mills, ship propulsion, offshore winches, large industrial gearboxes<\/td>\n<\/tr>\n
MOQ<\/td>\n1 set (fully custom per order)<\/td>\n<\/tr>\n
\u0e23\u0e30\u0e22\u0e30\u0e40\u0e27\u0e25\u0e32\u0e19\u0e33\u0e2a\u0e48\u0e07<\/td>\n15\u201320 working days for mass production; single-piece custom per negotiation<\/td>\n<\/tr>\n
\u0e40\u0e07\u0e37\u0e48\u0e2d\u0e19\u0e44\u0e02\u0e01\u0e32\u0e23\u0e0a\u0e33\u0e23\u0e30\u0e40\u0e07\u0e34\u0e19<\/td>\nEXW, FOB, CIF; T\/T and L\/C accepted<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Common Cast Steel Alloy Grade Equivalents<\/p>\n

\n\n\n\n\n\n\n\n
\u0e2a\u0e2b\u0e23\u0e32\u0e0a\u0e2d\u0e32\u0e13\u0e32\u0e08\u0e31\u0e01\u0e23 (\u0e08\u0e35\u0e19)<\/th>\n\u0e44\u0e2d\u0e42\u0e2d\u0e40\u0e2d\u0e2a<\/th>\n\u0e40\u0e2d\u0e2a\u0e40\u0e2d\u0e40\u0e2d\u0e2a\u0e17\u0e35<\/th>\n\u0e08\u0e35\u0e44\u0e2d\u0e40\u0e2d\u0e2a<\/th>\n\u0e14\u0e35\u0e40\u0e2d\u0e47\u0e19<\/th>\n<\/tr>\n
42CrMo<\/td>\n42CrMo4<\/td>\n4140<\/td>\n\u0e40\u0e2d\u0e2a\u0e0b\u0e35\u0e40\u0e2d\u0e47\u0e21440<\/td>\n42CrMo4<\/td>\n<\/tr>\n
40CrNiMoA<\/td>\n\u2014<\/td>\n4340<\/td>\nSNCM439<\/td>\n40NiCrMo6<\/td>\n<\/tr>\n
20CrNiMo<\/td>\n20CrNiMo2<\/td>\n8720<\/td>\nSNCM220<\/td>\n21NiCrMo2<\/td>\n<\/tr>\n
20CrNi2Mo<\/td>\n20NiCrMo7<\/td>\n4320<\/td>\nSNCM420<\/td>\n\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Why Cast Steel for Very Large Double Helical Gears<\/h2>\n

\"large<\/p>\n

The threshold above which cast steel becomes more practical than forged steel for gear blanks is approximately 2\u20135 tonnes finished weight, depending on the gear body geometry. Below this threshold, forging produces superior grain alignment and fatigue resistance and is preferred for all high-cycle, safety-critical applications (railway, aerospace, offshore). Above this threshold, forging press capacity, handling, and economics favor casting \u2014 particularly for double helical gears, where the herringbone tooth geometry adds complexity to an already large blank.<\/p>\n

Cast Steel Advantages for Large-Scale Gear Production<\/h3>\n