Full Gear Coupling Manufacturer in India
A full gear coupling is a flexible shaft coupling with two crowned-tooth gear hubs in a bolted, flanged sleeve, so each end takes angular misalignment and together they take parallel offset. Super Mech Industries makes them in Ahmedabad in 20 sizes, FG-100 to FG-119, rated 559 to 1,666,744 Nm, with bores up to 710 mm.
Flexible gear couplings designed to transmit torque while accommodating shaft misalignment in heavy industrial applications.
Key Features
- High torque capacity
- Misalignment compensation
- Torsionally rigid
- Low maintenance
Detailed Description
A full gear coupling (also called a full flexible gear coupling) consists of two inner hubs — each with externally crowned gear teeth — and an outer sleeve with internal straight teeth that meshes over both hubs simultaneously. The crown profile on the hub teeth allows each hub to rock inside the sleeve independently, accommodating angular and parallel misalignment on both the drive side and the driven side.
This "both ends flexible" design is what distinguishes a full gear coupling from a half gear coupling, where only one hub has gear teeth. In a full gear coupling, neither shaft end is rigidly constrained — both can misalign within the rated tolerance.
On the SMI FG series the sleeve is made in two flanged halves, bolted together through a gasket at the centre, and the gear teeth run in grease sealed inside the sleeve. From FG-111 onwards the sleeve ends use the cover-plate construction shown as Detail X on the spec sheet. The two gear meshes sit a distance apart, and that span turns the angle at each mesh into parallel offset — so the offset a coupling can take depends on its size. Ask SMI for the figure for your size.
- Best for: both shaft ends misaligned. Use a full gear coupling when the motor/gearbox output shaft and the driven machine shaft both have some degree of misalignment — e.g., between a gearbox and a rolling mill stand where thermal growth and foundation settlement cause both shafts to drift.
- Two gear meshes, two kinds of misalignment. With a gear mesh at each end, a full gear coupling takes angular misalignment at both ends and parallel offset between them — which a half gear coupling cannot do on its own.
Technical Specifications
- Construction: Two crowned-tooth gear hubs in a sleeve made of two flanged halves, bolted together
- Sizes: FG-100 to FG-119 (20 sizes)
- Rated torque: 559 to 1,666,744 Nm (57 to 169,961 Kg.M)
- Max bore D1: 35 mm (FG-100) to 710 mm (FG-119)
- Max speed: 7,600 rpm (FG-100) to 500 rpm (FG-119)
- Angular misalignment: Up to 1.5° per gear mesh
- FG-111 and larger: Cover-plate construction (Detail X on the spec sheet)
- Lubrication: EP2 grease packed inside the sleeve
Common Applications
- Steel rolling mills
- Cement kiln drives
- Ball mill drives
- Mining conveyor drives
- Crusher drives
- Multi-cylinder compressors
- Paper mill refiners
- Calender roll drives
- Gearbox-to-roll neck
- Power plant fan drives
- Sugar mill drives
- Slurry pump drives
Size chart, ratings and dimensions
Every size SMI manufactures, with its rated torque, speed limit, bore range and mounting dimensions as published on the spec sheet. Bores are finished to your shaft within the listed maximum; ask for the dimension drawing if a letter is unclear.
FG series full & half gear couplings — ratings and dimensions
Sizes FG-100 to FG-119. Power is at 100 rpm; rated torque in Nm; dimensions in mm; weight of solid-hub coupling in kg; WR² in kg·m².
| Size | kW at 100 rpm | Rated torqueNm | Max speedrpm | Pilot bore PBmm | Max bore D1mm | Max bore D2mm | ØAmm | Cmm | C1mm | ØBmm | ØB1mm | ØFmm | Mmm | Gmm | Jmm | Lmm | Weightkg | WR²kg·m² |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FG-100 | 5.9 | 559 | 7600 | 13 | 35 | 45 | 120 | 45 | 45 | 50 | 65 | 75 | 54 | 3 | 39 | 93 | 5 | 0.01 |
| FG-101 | 11.8 | 1127 | 6300 | 21 | 50 | 60 | 170 | 55 | 55 | 65 | 85 | 110 | 67 | 5 | 49 | 115 | 11 | 0.04 |
| FG-102 | 29.4 | 2804 | 5000 | 30 | 60 | 75 | 185 | 70 | 70 | 85 | 110 | 125 | 83 | 5 | 62 | 145 | 15 | 0.05 |
| FG-103 | 52.9 | 5047 | 4000 | 40 | 75 | 90 | 220 | 85 | 85 | 105 | 130 | 150 | 103 | 5 | 78 | 175 | 26 | 0.12 |
| FG-104 | 100 | 9557 | 3350 | 50 | 90 | 110 | 250 | 105 | 105 | 130 | 160 | 175 | 124 | 5 | 96 | 215 | 40 | 0.24 |
| FG-105 | 153 | 14605 | 2800 | 60 | 110 | 130 | 290 | 110 | 110 | 155 | 185 | 200 | 136 | 10 | 106 | 230 | 63 | 0.49 |
| FG-106 | 235 | 22444 | 2500 | 75 | 125 | 150 | 320 | 125 | 125 | 175 | 215 | 230 | 152 | 10 | 117 | 260 | 85 | 0.75 |
| FG-107 | 412 | 39303 | 2100 | 90 | 140 | 170 | 350 | 140 | 140 | 205 | 240 | 260 | 174 | 10 | 134 | 290 | 110 | 1.31 |
| FG-108 | 529 | 50472 | 1900 | 105 | 160 | 200 | 380 | 155 | 155 | 230 | 285 | 290 | 187 | 10 | 147 | 320 | 160 | 2.13 |
| FG-109 | 658 | 62821 | 1700 | 125 | 180 | 220 | 430 | 165 | 165 | 250 | 315 | 330 | 196 | 10 | 156 | 340 | 210 | 3.75 |
| FG-110 | 963 | 91923 | 1400 | 140 | 220 | 260 | 490 | 180 | 180 | 310 | 370 | 390 | 216 | 10 | 171 | 370 | 277 | 7.63 |
| FG-111 | 1289 | 123065 | 1250 | 160 | 260 | — | 545 | 200 | — | 350 | — | 445 | 245 | 10 | 191 | 410 | 550 | 14.5 |
| FG-112 | 1723 | 164516 | 1120 | 180 | 300 | — | 590 | 240 | — | 400 | — | 490 | 289 | 10 | 230 | 490 | 710 | 22 |
| FG-113 | 2344 | 223793 | 1000 | 200 | 330 | — | 680 | 260 | — | 440 | — | 555 | 312 | 15 | 241 | 535 | 980 | 34.5 |
| FG-114 | 3351 | 320012 | 900 | 220 | 370 | — | 730 | 280 | — | 500 | — | 610 | 341 | 15 | 265 | 575 | 1320 | 72.75 |
| FG-115 | 4071 | 388738 | 800 | 250 | 410 | — | 780 | 320 | — | 540 | — | 660 | 385 | 15 | 303 | 655 | 1700 | 88.25 |
| FG-116 | 7028 | 671165 | 710 | 300 | 455 | — | 900 | 350 | — | 625 | — | 755 | 423 | 20 | 333 | 720 | 2550 | 172 |
| FG-117 | 9997 | 954665 | 630 | 375 | 520 | — | 1000 | 400 | — | 720 | — | 855 | 489 | 20 | 384 | 820 | 3620 | 309 |
| FG-118 | 13236 | 1263938 | 560 | 450 | 610 | — | 1100 | 450 | — | 810 | — | 950 | 533 | 20 | 428 | 920 | 4860 | 491 |
| FG-119 | 17453 | 1666744 | 500 | 520 | 710 | — | 1250 | 485 | — | 910 | — | 1050 | 559 | 30 | 444 | 1000 | 6380 | 753 |
- Dimension letters (ØA, C, C1, ØB, ØB1, ØF, M, G, J, L) refer to the drawing on the SMI spec sheet.
- From FG-111 onwards the coupling uses the cover-plate construction shown as Detail X on the spec sheet; D2, C1 and ØB1 do not apply.
- FG-119: catalogue prints 174554 kW at 100 rpm; from the rated torque (T × n ÷ 9550) it is 17,453 kW, which is what is shown.
Source: SMI spec sheet full-gear-coupling.pdf
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Frequently Asked Questions
What is a full gear coupling?
A full gear coupling is a flexible shaft coupling with two gear hubs, each with crowned external teeth, meshing with the internal teeth of a sleeve. On the SMI FG series the sleeve is made in two flanged halves bolted together. With a flexible gear mesh at each end, it takes angular misalignment at both ends, parallel offset between the shafts, and axial float.
What is the difference between a full and a half gear coupling?
A full gear coupling has a flexible gear mesh at both ends, so it takes angular and parallel misalignment plus axial float. A half gear coupling has one gear mesh and one rigid flanged hub, so it takes angular misalignment at the gear end only and cannot take parallel offset on its own. SMI makes both on the same FG-100 to FG-119 sizes and torque ratings.
What sizes of full gear coupling does SMI make?
SMI makes 20 sizes, FG-100 to FG-119. Rated torque runs from 559 Nm at FG-100 to 1,666,744 Nm at FG-119, the maximum bore D1 from 35 mm to 710 mm, and the maximum speed from 7,600 rpm down to 500 rpm. The size chart on this page lists every dimension, weight and WR² value from the SMI spec sheet.
How do I choose the right full gear coupling size?
Work out the motor torque as T (Nm) = 9550 × kW ÷ rpm, multiply it by the service factor for the driven machine to get the design torque, then pick the smallest FG size rated above that figure whose maximum bore D1 fits your shaft. For example, 90 kW at 1,480 rpm is 581 Nm; with a service factor of 2.0 that is 1,162 Nm, so FG-101 (1,127 Nm) is too small and FG-102 (2,804 Nm, maximum bore 60 mm) is the size to check against the shaft. Heavy shock drives such as rolling-mill stands are usually sized with a service factor of 2.0 to 2.5.
Where are full gear couplings used?
Full gear couplings are used on high-torque drives where both shaft ends can move out of line: steel rolling mills, cement kiln and ball-mill drives, mining conveyors and crushers, paper mills, power generation, and pumps and compressors.
Can SMI machine a custom bore on a full gear coupling?
Yes. SMI finishes the bore and keyway to your shaft within the maximum bore D1 of each FG size, typically in 3–5 working days at its Odhav, Ahmedabad factory. Send the shaft diameter, keyway width and depth, and the tolerance class, usually H7.
Is Super Mech Industries ISO certified?
Yes. Super Mech Industries is ISO 9001:2015 certified (certificate no. 09114716A) and ZED certified. It makes its full gear couplings at Odhav, Ahmedabad, Gujarat, and exports to 29 countries.
Need a custom size or bore specification?
Our engineers will match the right coupling to your drawing — any bore size, material, or design.
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Super Mech Industries exports from Ahmedabad, India to 29 countries, shipping from Mundra Port (Gujarat) or JNPT (Nhava Sheva, Mumbai).
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Super Mech Industries — Odhav, Ahmedabad, Gujarat 382415, India. Phone: +91 63510 70577. Email: smigvs@gmail.com. ISO 9001:2015 certified.