{"id":1852,"date":"2026-07-20T05:25:04","date_gmt":"2026-07-20T05:25:04","guid":{"rendered":"https:\/\/gearrack.top\/?p=1852"},"modified":"2026-07-20T05:25:04","modified_gmt":"2026-07-20T05:25:04","slug":"spur-gears-for-electric-motor-drives","status":"publish","type":"post","link":"https:\/\/gearrack.top\/ko\/spur-gears-for-electric-motor-drives\/","title":{"rendered":"Spur Gears for Electric Motor Drives"},"content":{"rendered":"
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GEAR APPLICATION GUIDE \u00b7 SPUR GEAR \u00b7 S01<\/span><\/p>\n

Spur Gears for Electric Motor Drives:
\nSpeed Reduction and Torque Multiplication<\/span><\/h1>\n

Electric motors deliver peak torque at operating speed but most driven machinery requires lower shaft speed and higher output torque than the motor alone provides. Spur gear reducers bridge this gap \u2014 converting motor speed and torque through fixed ratio stages with efficiency above 98% per mesh. This guide covers spur gear ratio selection, stage configuration, efficiency calculation, and motor coupling design for AC and DC electric motor drive systems from 0.12 kW to 315 kW.<\/p>\n

C45 \u00b7 20CrMnTi \u00b7 316L \u00b7 Nylon<\/span>
\nM2 \u2013 M12 \u00b7 Ratio 2:1 \u2013 50:1<\/span>
\nIEC B3 \/ B5 \/ B14 Motor Mounting<\/span><\/div>\n<\/div>\n<\/div>\n
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MESH EFFICIENCY<\/p>\n

98 \u2013 99.5%<\/p>\n

Per spur gear mesh pair at rated load and correct lubrication \u2014 highest efficiency of any gear type. Two-stage drive: 96\u201399%; three-stage: 94\u201398.5%<\/p>\n<\/div>\n

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RATIO PER STAGE<\/p>\n

2:1 \u2013 8:1<\/p>\n

Practical single spur gear stage ratio range for enclosed motor gearboxes. Two stages: up to 25:1; three stages: up to 50:1. Higher ratios use planetary or worm stages<\/p>\n<\/div>\n

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TORQUE MULTIPLIED<\/p>\n

\u00d7 ratio \u00d7 \u03b7<\/p>\n

Output torque = motor torque \u00d7 gear ratio \u00d7 efficiency. A 5 Nm motor through 10:1 spur gear reducer at 98.5% efficiency: 5 \u00d7 10 \u00d7 0.985 = 49.25 Nm output<\/p>\n<\/div>\n

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MOTOR FRAME RANGE<\/p>\n

IEC 56 \u2013 315<\/p>\n

Korea Ever-Power spur gear reducers flanged to IEC 56\u2013315 motor frames via B5 or B14 face mount. Foot-mount B3 also available for base-plate motor arrangements<\/p>\n<\/div>\n<\/div>\n

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Why Electric Motor Drives Need Spur Gear Reduction<\/h2>\n

The AC induction motor and the BLDC motor share a fundamental characteristic: their rated torque output is achieved at rated speed, and that speed is almost always higher than the driven machinery requires. A standard 4-pole AC induction motor operates at 1,450\u20131,480 RPM on 50 Hz supply; a 2-pole motor runs at 2,860\u20132,900 RPM. The majority of driven applications \u2014 conveyor belts at 0.5\u20132 m\/s, mixer agitators at 40\u2013200 RPM, pump impellers at 300\u2013900 RPM \u2014 operate far below these speeds and require proportionally higher torques than the motor shaft delivers directly.<\/p>\n

Korea Ever-Power’s spur gears for electric motor drives<\/a> are specified and manufactured for direct coupling to IEC-frame AC motors from 0.12 kW (IEC 56 frame) to 315 kW (IEC 315 frame). The spur gear reducer is the most efficient gear type available for this speed reduction function \u2014 per-mesh efficiency of 98\u201399.5% means minimal heat generation and minimal additional motor loading vs the worm gear alternative that loses 10\u201350% of motor power to friction at high reduction ratios.<\/p>\n

Beyond efficiency, the spur gear drive for electric motor applications offers a second advantage: predictable backlash. For servo motor and stepper motor drives where positioning accuracy is a requirement, the known and measurable backlash of a spur gear reducer \u2014 set by the centre distance and tooth thickness at manufacture \u2014 allows the control system to compensate for gear lash in the positioning algorithm. Worm gear reducers have less predictable backlash that changes with wear, making spur gear reducers the preferred choice for servo-driven positioning axes at ratios below 20:1.<\/p>\n

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MOTOR DRIVE REDUCTION \u2014 KEY DESIGN EQUATIONS<\/p>\n

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Required Ratio<\/p>\n

i = nmotor<\/sub> \u00f7 noutput<\/sub>. Example: motor 1,450 RPM, required output 145 RPM: i = 10:1. If a single stage is limited to 8:1, use two stages: i1<\/sub> = 3.16, i2<\/sub> = 3.16, total = 10:1 (equal stages minimise gearbox size).<\/p>\n<\/div>\n

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Output Torque<\/p>\n

Tout<\/sub> = Tmotor<\/sub> \u00d7 i \u00d7 \u03b7n<\/sup> where n = number of stages. Motor 9.55 Nm at 1,450 RPM, 2-stage i = 10, \u03b7 = 0.985 per stage: Tout<\/sub> = 9.55 \u00d7 10 \u00d7 0.985\u00b2 = 92.7 Nm.<\/p>\n<\/div>\n

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Motor Power from Load<\/p>\n

Pmotor<\/sub> = (Tload<\/sub> \u00d7 noutput<\/sub>) \u00f7 (9,550 \u00d7 \u03b7n<\/sup>). Load 200 Nm at 80 RPM, 2 spur stages, \u03b72<\/sup> = 0.97: Pmotor<\/sub> = (200 \u00d7 80) \u00f7 (9,550 \u00d7 0.97) = 1.73 kW \u2192 select 2.2 kW motor.<\/p>\n<\/div>\n

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Service Factor<\/p>\n

Design power = Pmotor<\/sub> \u00d7 Ks<\/sub> where Ks<\/sub> = 1.0\u20131.25 for smooth electric motor drives; 1.25\u20131.5 for motors with frequent starts\/stops; 1.5\u20132.0 for motors with severe shock loading. Spur gear module selected for design power, not nameplate motor power.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Stage Configuration and Ratio Splitting<\/h2>\n
\"steel
Korea Ever-Power C45 induction-hardened spur gear for AC electric motor reducer application \u2014 M5, 24T pinion and 96T wheel (4:1 ratio), face width 60 mm, HRC 50\u201354 tooth surface. Centre distance 300 mm, pitch line velocity 2.3 m\/s at 1,450 RPM motor input. Transmission efficiency 98.7% measured at rated torque. Matched set supplied with individual measurement report confirming module, tooth count, pitch diameter, and DIN quality class.<\/figcaption><\/figure>\n
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CONFIG 01<\/p>\n

SINGLE STAGE
\n2:1 \u2013 8:1<\/p>\n<\/div>\n

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Design:<\/strong> One pinion-and-wheel pair. Minimum pinion 17 teeth to avoid undercutting at 20\u00b0 pressure angle; maximum practical wheel teeth 120\u2013130T before gear OD becomes incompatible with IEC motor frame dimensions. Single-stage ratio ceiling 8:1 (17T pinion \/ 136T wheel) for standard proportions. Applications: pump drives, fan drives, mixer agitators, and roller table drives where the required output speed is above 200 RPM. Most compact arrangement; highest efficiency (>99% per mesh at correct lubrication).<\/p>\n<\/div>\n<\/div>\n

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CONFIG 02<\/p>\n

TWO STAGE
\n8:1 \u2013 25:1<\/p>\n<\/div>\n

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Design:<\/strong> Two spur gear pairs in a common housing on three parallel shafts. Equal ratio split between stages minimises total gearbox size for a given overall ratio: for i = 16:1, use i1<\/sub> = 4:1 and i2<\/sub> = 4:1 rather than 8:1 and 2:1 (equal stages produce the smallest gearbox footprint for the given ratio). Two-stage overall efficiency 96\u201399%. Applications: conveyor head drives, crane hoist drives, mixer drives requiring output speeds of 50\u2013200 RPM from a 1,450 RPM 4-pole motor.<\/p>\n<\/div>\n<\/div>\n

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CONFIG 03<\/p>\n

THREE STAGE
\n25:1 \u2013 50:1<\/p>\n<\/div>\n

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Design:<\/strong> Three spur gear pairs in line. Practical for up to 50:1 overall ratio with manageable gearbox dimensions. Above 50:1, a planetary first stage or worm gear stage is usually more compact. Three-stage efficiency 94\u201398.5%. Applications: slow-speed conveyor drives below 50 RPM output, gate and sluice valve drives, kiln slow-speed turning drives, and lifting winch drives where the low output speed requires extended gear trains from a standard motor speed.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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C45 Induction Hardened<\/p>\n

The standard for enclosed motor gearbox spur gears in the 2.2\u201355 kW range. HRC 48\u201354 tooth flank and root, \u03c3H<\/sub> = 900\u20131,050 MPa. Motor gearbox loads are smooth and continuous \u2014 no shock service factor premium needed. Cost-effective for standard IEC motor frame gearboxes at PLV below 5 m\/s. Fastest lead time of all steel spur gear options \u2014 Korea Ever-Power stocks C45 induction-hardened blanks in M4, M5, M6, M8 for fast turnaround motor gearbox orders.<\/p>\n

\u2713 2.2\u201355 kW motor drive standard<\/p>\n<\/div>\n

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20CrMnTi Case Carburized<\/p>\n

For electric motor drives above 55 kW, high duty cycle (24\/7 operation), or motor drives with frequent starts\/stops imposing cyclic loading. Case depth 0.8\u20131.5 mm, HRC 58\u201362, \u03c3F<\/sub> = 380\u2013430 MPa \u2014 provides 2.5\u20133\u00d7 the fatigue life of C45 induction hardened at the same module and face width. Ground to DIN 6 for motor gearboxes at PLV above 5 m\/s or where gear noise is a specification requirement (indoor industrial, HVAC motor drives).<\/p>\n

\u2713 Above 55 kW, 24\/7 or servo motor drives<\/p>\n<\/div>\n

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316L Stainless<\/p>\n

For electric motor drives in corrosive environments \u2014 marine deck motor drives, chemical plant motor-driven pumps, food processing motor gearboxes. HB 160\u2013200, lower load rating than carbon steel \u2014 increase module by one size vs C45 calculation. NSF H1 lubricant compatible. CIP washdown-proof for food processing motor drive applications. Korea Ever-Power supplies 316L spur gear motor drive sets with FDA documentation on request.<\/p>\n

\u2713 Marine, food, chemical motor drive<\/p>\n<\/div>\n

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Nylon \/ POM Plastic<\/p>\n

Plastic spur gears<\/a> for low-power motor drives to 0.75 kW \u2014 servo motor final stage, stepper motor output, BLDC motor drives in office equipment and consumer products. Self-lubricating, low inertia, low noise, zero corrosion. MC Nylon oil-grade preferred for enclosed plastic spur gear motor drives above 0.37 kW for its higher fatigue strength and oil absorption lubrication property.<\/p>\n

\u2713 Low-power servo, stepper, BLDC drives<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Motor Coupling, Mounting and Thermal Rating<\/h2>\n
\"spur
Korea Ever-Power DIN 867 and EN ISO 54 standard spur gears for European motor drive applications \u2014 module series M2 to M12, pressure angle 20\u00b0, quality DIN 6\u20138, addendum 1.0\u00d7m, dedendum 1.25\u00d7m. Interchangeable with all DIN\/ISO standard motor gearbox spur gears from European gearbox manufacturers. Available as standard catalogue items in C45 normalised, C45 induction hardened, and 20CrMnTi case carburized for all IEC motor frame gearbox replacement applications.<\/figcaption><\/figure>\n
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MOTOR COUPLING<\/h3>\n