Gear Coupling Size Chart — FG, HRC, Tyre & Jaw Sizes (2026)
Gear coupling size chart for India — FG-100 to FG-119 full and half gear couplings with kW, torque, speed and bore per size from the SMI spec sheet, plus SHRC 70–280, tyre and jaw sizes. Full dimension tables on each product page.
SMI gear couplings come in 20 sizes, FG-100 to FG-119, rated from 559 Nm to 1,666,744 Nm, with finished bores up to 710 mm and maximum speeds from 7,600 rpm (FG-100) down to 500 rpm (FG-119). Full and half gear couplings share this one size series.
Looking for an FGC size, such as FGC 7? Some catalogues label full gear couplings "FGC" with their own size numbers, and those numbers do not carry across makers. SMI sizes its gear couplings FG-100 to FG-119. Send the FGC number from the old coupling with both shaft bores and the motor kW and rpm, and we will match the FG size from the ratings in the tables below.
The two size charts below give the rated torque, speed limit, bores and every dimension for each size, taken from SMI's spec sheet; SHRC, tyre and jaw coupling sizes follow further down.
Other makers' size codes and dimensions differ; the charts below are SMI's. When replacing another make, confirm against your drawing or the existing coupling before ordering.
Full gear coupling size chart (FG-100 to FG-119)
A full gear coupling has two gear hubs meshing in one sleeve, so both shaft ends can flex. This chart lists all 20 sizes with rated torque, maximum speed, pilot bore PB, maximum finished bore D1 and the mounting dimensions from the spec-sheet drawing.
| Size | kW at 100 rpm | Rated torque (Nm) | Max speed (rpm) | Pilot bore PB (mm) | Max bore D1 (mm) | ØA (mm) | C (mm) | ØB (mm) | ØF (mm) | M (mm) | G (mm) | J (mm) | L (mm) | Weight (kg) | WR² (kg·m²) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FG-100 | 5.9 | 559 | 7,600 | 13 | 35 | 120 | 45 | 50 | 75 | 54 | 3 | 39 | 93 | 5 | 0.01 |
| FG-101 | 11.8 | 1,127 | 6,300 | 21 | 50 | 170 | 55 | 65 | 110 | 67 | 5 | 49 | 115 | 11 | 0.04 |
| FG-102 | 29.4 | 2,804 | 5,000 | 30 | 60 | 185 | 70 | 85 | 125 | 83 | 5 | 62 | 145 | 15 | 0.05 |
| FG-103 | 52.9 | 5,047 | 4,000 | 40 | 75 | 220 | 85 | 105 | 150 | 103 | 5 | 78 | 175 | 26 | 0.12 |
| FG-104 | 100 | 9,557 | 3,350 | 50 | 90 | 250 | 105 | 130 | 175 | 124 | 5 | 96 | 215 | 40 | 0.24 |
| FG-105 | 153 | 14,605 | 2,800 | 60 | 110 | 290 | 110 | 155 | 200 | 136 | 10 | 106 | 230 | 63 | 0.49 |
| FG-106 | 235 | 22,444 | 2,500 | 75 | 125 | 320 | 125 | 175 | 230 | 152 | 10 | 117 | 260 | 85 | 0.75 |
| FG-107 | 412 | 39,303 | 2,100 | 90 | 140 | 350 | 140 | 205 | 260 | 174 | 10 | 134 | 290 | 110 | 1.31 |
| FG-108 | 529 | 50,472 | 1,900 | 105 | 160 | 380 | 155 | 230 | 290 | 187 | 10 | 147 | 320 | 160 | 2.13 |
| FG-109 | 658 | 62,821 | 1,700 | 125 | 180 | 430 | 165 | 250 | 330 | 196 | 10 | 156 | 340 | 210 | 3.75 |
| FG-110 | 963 | 91,923 | 1,400 | 140 | 220 | 490 | 180 | 310 | 390 | 216 | 10 | 171 | 370 | 277 | 7.63 |
| FG-111 | 1,289 | 123,065 | 1,250 | 160 | 260 | 545 | 200 | 350 | 445 | 245 | 10 | 191 | 410 | 550 | 14.5 |
| FG-112 | 1,723 | 164,516 | 1,120 | 180 | 300 | 590 | 240 | 400 | 490 | 289 | 10 | 230 | 490 | 710 | 22 |
| FG-113 | 2,344 | 223,793 | 1,000 | 200 | 330 | 680 | 260 | 440 | 555 | 312 | 15 | 241 | 535 | 980 | 34.5 |
| FG-114 | 3,351 | 320,012 | 900 | 220 | 370 | 730 | 280 | 500 | 610 | 341 | 15 | 265 | 575 | 1,320 | 72.75 |
| FG-115 | 4,071 | 388,738 | 800 | 250 | 410 | 780 | 320 | 540 | 660 | 385 | 15 | 303 | 655 | 1,700 | 88.25 |
| FG-116 | 7,028 | 671,165 | 710 | 300 | 455 | 900 | 350 | 625 | 755 | 423 | 20 | 333 | 720 | 2,550 | 172 |
| FG-117 | 9,997 | 954,665 | 630 | 375 | 520 | 1,000 | 400 | 720 | 855 | 489 | 20 | 384 | 820 | 3,620 | 309 |
| FG-118 | 13,236 | 1,263,938 | 560 | 450 | 610 | 1,100 | 450 | 810 | 950 | 533 | 20 | 428 | 920 | 4,860 | 491 |
| FG-119 | 17,453 | 1,666,744 | 500 | 520 | 710 | 1,250 | 485 | 910 | 1,050 | 559 | 30 | 444 | 1,000 | 6,380 | 753 |
Source: SMI spec sheet full-gear-coupling.pdf (PDF).
Rated power at 100 rpm is torque × 100 ÷ 9,550; at any other speed it scales in proportion (kW = torque × rpm ÷ 9,550). The sheet prints 174,554 kW for FG-119; the correct figure from its torque is 17,453 kW, which is what the table shows. Dimension letters (ØA, C, ØB, ØF, M, G, J, L) refer to the full gear coupling drawing on the spec sheet; weight and WR² are the sheet's solid-hub values. From FG-111 onwards the coupling uses the cover-plate construction shown as Detail X on the sheet.
Half gear coupling size chart (FG-100 to FG-119)
Half gear couplings use the same 20 sizes, FG-100 to FG-119, with the same torque ratings and speed limits as the full gear type. The difference is the second hub: a rigid flange hub replaces one gear hub, so a half gear coupling has two bore limits — D1 for the flexible gear hub (35 mm at FG-100 up to 710 mm at FG-119) and D2 for the rigid flange hub (45 mm at FG-100 up to 260 mm at FG-110).
| Size | kW at 100 rpm | Rated torque (Nm) | Max speed (rpm) | Pilot bore PB (mm) | Max bore D1 (mm) | Max bore D2 (mm) | ØA (mm) | C (mm) | C1 (mm) | ØB (mm) | ØB1 (mm) | ØF (mm) | M (mm) | G (mm) | J (mm) | L (mm) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FG-100 | 5.9 | 559 | 7,600 | 13 | 35 | 45 | 120 | 45 | 45 | 50 | 65 | 75 | 54 | 3 | 39 | 93 |
| FG-101 | 11.8 | 1,127 | 6,300 | 21 | 50 | 60 | 170 | 55 | 55 | 65 | 85 | 110 | 67 | 5 | 49 | 115 |
| FG-102 | 29.4 | 2,804 | 5,000 | 30 | 60 | 75 | 185 | 70 | 70 | 85 | 110 | 125 | 83 | 5 | 62 | 145 |
| FG-103 | 52.9 | 5,047 | 4,000 | 40 | 75 | 90 | 220 | 85 | 85 | 105 | 130 | 150 | 103 | 5 | 78 | 175 |
| FG-104 | 100 | 9,557 | 3,350 | 50 | 90 | 110 | 250 | 105 | 105 | 130 | 160 | 175 | 124 | 5 | 96 | 215 |
| FG-105 | 153 | 14,605 | 2,800 | 60 | 110 | 130 | 290 | 110 | 110 | 155 | 185 | 200 | 136 | 10 | 106 | 230 |
| FG-106 | 235 | 22,444 | 2,500 | 75 | 125 | 150 | 320 | 125 | 125 | 175 | 215 | 230 | 152 | 10 | 117 | 260 |
| FG-107 | 412 | 39,303 | 2,100 | 90 | 140 | 170 | 350 | 140 | 140 | 205 | 240 | 260 | 174 | 10 | 134 | 290 |
| FG-108 | 529 | 50,472 | 1,900 | 105 | 160 | 200 | 380 | 155 | 155 | 230 | 285 | 290 | 187 | 10 | 147 | 320 |
| FG-109 | 658 | 62,821 | 1,700 | 125 | 180 | 220 | 430 | 165 | 165 | 250 | 315 | 330 | 196 | 10 | 156 | 340 |
| FG-110 | 963 | 91,923 | 1,400 | 140 | 220 | 260 | 490 | 180 | 180 | 310 | 370 | 390 | 216 | 10 | 171 | 370 |
| FG-111 | 1,289 | 123,065 | 1,250 | 160 | 260 | — | 545 | 200 | — | 350 | — | 445 | 245 | 10 | 191 | 410 |
| FG-112 | 1,723 | 164,516 | 1,120 | 180 | 300 | — | 590 | 240 | — | 400 | — | 490 | 289 | 10 | 230 | 490 |
| FG-113 | 2,344 | 223,793 | 1,000 | 200 | 330 | — | 680 | 260 | — | 440 | — | 555 | 312 | 15 | 241 | 535 |
| FG-114 | 3,351 | 320,012 | 900 | 220 | 370 | — | 730 | 280 | — | 500 | — | 610 | 341 | 15 | 265 | 575 |
| FG-115 | 4,071 | 388,738 | 800 | 250 | 410 | — | 780 | 320 | — | 540 | — | 660 | 385 | 15 | 303 | 655 |
| FG-116 | 7,028 | 671,165 | 710 | 300 | 455 | — | 900 | 350 | — | 625 | — | 755 | 423 | 20 | 333 | 720 |
| FG-117 | 9,997 | 954,665 | 630 | 375 | 520 | — | 1,000 | 400 | — | 720 | — | 855 | 489 | 20 | 384 | 820 |
| FG-118 | 13,236 | 1,263,938 | 560 | 450 | 610 | — | 1,100 | 450 | — | 810 | — | 950 | 533 | 20 | 428 | 920 |
| FG-119 | 17,453 | 1,666,744 | 500 | 520 | 710 | — | 1,250 | 485 | — | 910 | — | 1,050 | 559 | 30 | 444 | 1,000 |
Source: SMI spec sheet half-gear-coupling.pdf (PDF).
On the half gear coupling drawing, D1, C and ØB belong to the gear hub and D2, C1 and ØB1 to the rigid flange hub. The spec sheet lists D2, C1 and ØB1 only up to FG-110; for FG-111 to FG-119, send a drawing of the mating flange with your enquiry.
For the half gear coupling, the flexible half takes the angular misalignment and the rigid flange bolts to the machine, so parallel offset must be absorbed elsewhere in the train. Selection is otherwise identical: design torque = motor torque × service factor, then the first FG size whose rated torque exceeds it. The full vs half gear coupling guide covers when each type is the right one.
SHRC coupling sizes
SMI's HRC couplings are the SHRC series: SHRC 70, 90, 110, 130, 150, 180, 230 and 280, taper-bush or pilot-bore mounted. Ratings and dimensions for each size are on the product page.
Tyre Coupling sizes (F-series)
Tyre couplings: F40, F50, F60, F70, F80, F90, F100, F110, F120, F140, in pilot bore (A) or taper bush (TC).
Jaw / star coupling sizes (SJC series)
SMI's jaw (star) couplings are the SJC series: SJC 75, 90, 95, 99, 100, 110, 150, 190, 225, 226, 276, 280 and 295, with elastomer spider. Ratings and dimensions for each size are on the product page.
How to use this chart
- Identify the family (gear, tyre, HRC, jaw) by your application and misalignment needs.
- Match required torque and shaft bore to the size step.
- Read the dimensions for your size from the tables above, then confirm them against your drawing or existing coupling — or send your shaft size and a photo of the existing coupling.
Identifying a coupling when the markings are gone
Most enquiries that start "I need a replacement, I do not know the size" can be answered from measurements alone. Take these and we can identify the family and size without you stripping the drive twice.
| Coupling family | Measure these |
|---|---|
| Gear coupling (FG series) | Sleeve outside diameter, overall length, flange bolt circle and bolt count, both bores with keyways, hub tooth outside diameter if the sleeve is off |
| Tyre coupling (F-series) | Rubber element outside diameter and width, flange outside diameter, bolt circle, number of clamping bolts |
| HRC coupling | Hub outside diameter, overall assembled length, element outside diameter, taper bush number if visible |
| Jaw / star coupling (SJC series) | Hub outside diameter, hub length, number of jaws, spider outside diameter |
Always measure the bore and keyway yourself rather than trusting an old drawing. Shafts get reworked, keyways get widened by a worn key, and a "50 mm" shaft that has been running loose may measure 49.6 mm. We machine to what is actually there.
What a size code does and does not tell you
Every series on this page is a size designation, not a specification. Two couplings marked the same size from different makers can differ in outside diameter, length, bolt circle and exact torque rating. What the code reliably tells you is the approximate torque class and bore range. What it does not tell you is whether the part will physically drop into your machine.
That is why the practical sequence is always: identify the family, narrow to the size step by torque and bore, then confirm the actual dimensions against your existing part or drawing before manufacture. On a replacement job we would rather see one photograph and four measurements than a size code alone.
Bore and keyway: the details that hold up orders
- Give the measured shaft diameter, not the nominal one, and say whether the shaft is worn.
- Give keyway width and depth, and say whether it is a single or double keyway. Parallel keys to IS 2048 are standard on most Indian equipment; if yours is a different standard or a non-standard key, say so.
- State the fit you want — interference, transition or clearance with a grub screw. Different machines want different answers and "standard" is not one.
- Tapered shafts need the taper ratio and the shaft end dimensions. Send a sketch.
- Say if the coupling will be fitted with heat. An interference fit intended to be shrunk on is machined differently from one meant to be pressed.
Getting from a size to a purchase order
The size chart narrows the field. These four items close the order:
- Service-factored torque. Calculate T = 9,550 × kW ÷ RPM at the coupling, then multiply by the duty factor for the driven machine. Size on that number, not on motor kW.
- Both bores and keyways, measured.
- Distance between shaft ends, plus any axial float the machine needs.
- Duty and environment — continuous or start-stop, reversing, ambient temperature, dust, oil exposure.
Our torque calculator does the first step, and the selection guide gives the service factor for each type of driven machine, with a worked example.
Cross-family quick reference
| Family | Series | Reach for it when |
|---|---|---|
| Full gear coupling | FG-100 – FG-119 | Highest torque, significant misalignment, heavy industry |
| Half gear coupling | FG-100 – FG-119 (half) | One flexible end is enough — floating shaft and similar arrangements |
| Grid coupling | By torque and bore | Shock loads, reversals, compressors and crushers |
| Tyre coupling | F40 – F140 | Large misalignment, shock, no lubrication wanted |
| HRC coupling | SHRC 70 – 280 | General-purpose pumps, fans and light drives |
| Jaw / star coupling | SJC 75 – 295 | Small to medium general drives, vibration damping |
| Chain coupling | By torque and bore | High torque, low speed, dirty conditions |
Detailed comparisons for the flexible families are in the coupling selection guide, and for grid couplings specifically in the grid coupling guide.
What to send us to get a spec sheet or a quote
- The size marking if it is legible, plus a photograph of the coupling in place.
- The measurements for your family from the identification table above.
- Both shaft diameters and keyway sizes, measured.
- Motor kW, RPM and the driven machine.
- Distance between shaft ends.
- Quantity and delivery location.
Frequently asked questions
What sizes do gear couplings come in?
SMI full gear couplings come in 20 sizes, FG-100 to FG-119, rated 559 to 1,666,744 Nm with finished bores up to 710 mm and maximum speeds from 7,600 rpm (FG-100) down to 500 rpm (FG-119). Half gear couplings share the same FG-100 to FG-119 series and ratings, with one flexible hub and one rigid flange.
Is there a separate half gear coupling size chart?
Half gear couplings use the same FG-100 to FG-119 sizes, torque ratings and speed limits as full gear couplings. Their chart adds the rigid flange hub: maximum bore D2 (45 mm at FG-100 up to 260 mm at FG-110) and the hub dimensions C1 and ØB1, which the spec sheet lists up to FG-110.
What bore sizes are available for gear couplings?
The pilot bore runs from 13 mm at FG-100 to 520 mm at FG-119, and bores are finished to your shaft up to the maximum bore D1: 35 mm at FG-100 to 710 mm at FG-119. On a half gear coupling the rigid flange hub has its own limit, D2, from 45 mm at FG-100 to 260 mm at FG-110.
How do I choose the right gear coupling size?
Calculate the design torque as 9,550 × kW ÷ rpm × service factor, then pick the first FG size whose rated torque is at least that. Check that your shaft fits within that size's maximum bore D1 and that your speed is within its maximum rpm; if either fails, move up a size. The selection guide has the service factor table and a worked example.
How do I identify a coupling with no visible markings?
Measure the family-specific dimensions — for a gear coupling that is sleeve outside diameter, overall length, flange bolt circle and bolt count, plus both bores and keyways. Send those with a photograph of the coupling in place and we can identify the size.
Does the same size code mean the same dimensions from every manufacturer?
No. A size code reliably indicates a torque class and bore range, but outside diameter, length, bolt circle and exact torque rating vary between makers. Always confirm actual dimensions against your existing part or drawing before manufacture.
Should I give you the nominal shaft size or the measured one?
The measured one, always. Shafts get reworked and worn, and keyways widen under a loose key. We machine to what is actually on your machine, so a measured diameter and keyway prevent a coupling that will not fit or will not grip.
Can you supply a coupling for a tapered or non-standard shaft?
Yes. Send the taper ratio and shaft end dimensions, or a sketch with measurements, along with the fit you need and whether the coupling will be heated on.
Need help sizing? See our selection guide or contact SMI's engineers for a recommendation and quote. SMI makes the FG-100 to FG-119 sizes above in Ahmedabad and dispatches them across India; for certification, dispatch and export details, see our page for buyers comparing gear coupling manufacturers in India.
Super Mech Industries — Odhav, Ahmedabad, Gujarat 382415, India. Phone: +91 63510 70577. Email: smigvs@gmail.com. ISO 9001:2015 certified.