AG Series vs EA Series Gear Couplings: Choosing the Right Range
Most coupling enquiries we get start the same way. Someone has a motor, a gearbox and a shaft of a particular size, and they want to know whether they need an AG or an EA. The honest answer is that four or five numbers decide it, and the series name is the last thing to settle.
Both ranges are geared couplings with crowned hub teeth, and both handle angular, parallel and axial misalignment. Where they differ is size range, how torque is rated, weight, and the room they need. This page compares the published data for the AG Series gear couplings and the EA Series gear couplings, then runs one selection from start to finish.
AG Series vs EA Series at a Glance
Every figure below comes from the published product pages.
| Parameter | AG Series | EA Series |
|---|---|---|
| Sizes | 19 sizes, AG-101 to AG-119 | 12 sizes, EA130 to EA17400 |
| Published torque | 1,100 to 1,470,000 Nm (one figure per size) | 1,300 to 174,000 Nm nominal; 2,600 to 348,000 Nm maximum |
| Bore range | 14 mm minimum bore up to 710 mm (flex) | 10 mm pilot bore up to 275 mm |
| Maximum speed | Published per size: 6,700 rpm (AG-101) down to 825 rpm (AG-119) | Not listed on the product page |
| Misalignment | Angular, parallel and axial capability stated; numeric limits not listed | 2 x 0.75 degrees angular; parallel from ±0.35 mm to ±1.7 mm by size |
| Approx. weight | 11 kg (AG-101) to 5,590 kg (AG-119) | 4 kg (EA130) to 414 kg (EA17400) |
| Tooth and flex options | ST and LT; full-flex and half-flex | ST and LT |
| Material and finish | EN9 / C45 steel hubs, CED coated | EN9 steel, CED coated |
| Lubrication | EP2 grease, 75% cavity fill | EP2 grease, 75% cavity fill |
Two things in that table deserve a second look. Torque is presented differently in each range, and each page leaves out something the other one publishes. Both come up below.
What the AG Series Is, From a Selection Point of View
AG is the broad range. Nineteen sizes cover everything from a 1,100 Nm drive to one near 1.5 million Nm, in full-flex and half-flex versions and in both ST and LT tooth profiles. That spread is why AG is usually where you land when the shaft is large, the torque is very high, or the layout needs a half-flex arrangement. The full dimension table, installation steps and maintenance notes sit on the AG Series page, so we won't repeat them here.
What the EA Series Is, From a Selection Point of View
EA is the narrower and more compact range: twelve sizes from EA130 to EA17400, each with a nominal torque and a maximum rating at double that. It is designed for a high power-to-weight ratio, which matters where space and shaft load are tight. Unlike the AG page, the EA Series page gives numeric misalignment limits for every size, so early design checks are easier.
Six Checks That Separate AG From EA
1. Torque
Work out the torque the drive puts through the coupling: 9,550 × kW ÷ rpm gives Nm. A 250 kW motor at 1,000 rpm is about 2,390 Nm. Multiply by the service factor for the driven machine, then check starting and peak loads separately. A jammed crusher doesn’t care what the motor nameplate says.
Be careful when you compare tables. EA lists a nominal torque and a maximum that is exactly double. The AG table shows one figure per size, and it tracks the power-at-100-rpm rating (AG-103 is rated 51.5 kW at 100 rpm, which works out to about 4,918 Nm, and the table says 4,920). That suggests a continuous rating, so the fair comparison is AG’s figure against EA’s nominal torque, not EA’s maximum. Ask us to confirm the basis for your size before you shortlist.
2. Shaft diameter and bore
Torque gives you a shortlist. The shafts usually cut it. Measure both shaft ends, note the keyways, and check them against the maximum bore of the size you picked. EA stops at 275 mm. If either shaft is bigger, you are choosing within AG, which reaches 710 mm. In the middle the ranges overlap: EA500 and AG-103 both take shafts up to 75 mm. Either range can be bored and keyed to your drawing, so send the drawing early.
3. Misalignment
Don’t assume every size gives the same movement. EA lists 2 x 0.75 degrees angular, and parallel offset from ±0.35 mm on EA130 to ±1.7 mm on EA17400. The AG page states the capability in words without numbers, so ask us for the limit on your size. If your machines have soft foot, thermal growth or a base that moves, set these figures against your measured misalignment. The word “flexible” tells you very little.
4. Installation space
A coupling can have plenty of torque and still not fit. Check outside diameter, overall length, the gap between shaft ends, and the room you need to slide a sleeve back for inspection. On the published tables EA comes out smaller and lighter at comparable ratings. EA17400 lists 174,000 Nm nominal at 414 kg with an A dimension of 506 mm. AG-112 lists 152,800 Nm at 630 kg with 590 mm. Dimension letters can mean different things between tables, so check the drawings before you trust the comparison.
5. Speed
AG publishes a maximum speed for every size, and it falls as the coupling grows. A big size picked purely for torque can fail the speed check. Above 3,000 rpm, both pages call for balance grade G6.3 or better. The EA page doesn’t list a maximum speed, so for a fast drive ask us for the figure for your size. Check rpm against the exact model, never against the series name.
6. ST or LT teeth
Both ranges come in either tooth version. Short teeth allow more angular movement. Long teeth spread the load over more contact area and allow slightly less movement. It comes down to alignment against load, and the AG Series page explains the difference in full.
Which Range Should You Start With?
Treat this as a starting point, not a verdict.
| If your situation is | Start with |
|---|---|
| Either shaft needs a bore above 275 mm | AG. EA stops at 275 mm and AG goes to 710 mm. |
| Continuous torque beyond 174,000 Nm | AG, from AG-113 upwards. |
| Mid-range torque with tight space or a weight limit | Compare EA first. It is smaller and lighter at similar ratings on the published tables. |
| You need numeric misalignment limits at design stage | EA publishes them. Ask us for the AG figures. |
| Fast drive, above 3,000 rpm | Check the exact size's speed limit. AG publishes it; ask us for EA. |
| Replacing an existing coupling | Match bore, keyway, shaft gap and overall length first. Series comes second. |
| Half-flex layout | AG. It is the range that lists half-flex. |
How the Plant Changes the Question
Steel plants
Rolling drives reverse and take shock, so peak torque matters more than running torque. Ask what happens at a stalled roll, and how much alignment shifts once the stand heats up.
Cement plants
Kiln and mill drives run for months in dust, with high torque and big shafts. Bore is often the first filter. Plan grease checks around planned shutdowns.
Sugar mills
A mill works hard for a season and then sits idle. Torque spikes when cane feed is uneven. Regrease before the season starts and look at the seals after a long standstill.
Power plants
Speed and balance come first, and torque is rarely the problem. Check the maximum rpm of the exact size, the balance grade, and alignment after thermal growth.
Conveyors and material handling
A loaded belt restarts harder than it runs, so find the starting torque under load. On retrofits, the space and shaft gap usually pick the size.
A Selection From Start to Finish
This is the order we work in when an enquiry arrives.
- 1. Calculate operating torque from kW and rpm.
- 2. Apply the service factor for the driven machine.
- 3. Check start-up and peak torque against the maximum rating.
- 4. Measure both shafts and keyways against the bore range.
- 5. Check operating speed against the size’s limit.
- 6. Compare real misalignment with the permitted movement.
- 7. Compare outside diameter, length and shaft gap with the space you have.
- 8. Choose ST or LT teeth.
- 9. Confirm EP2 grease, the fill and a service interval.
- 10. Have our engineers verify the final selection.
Worked example: 250 kW at 1,000 rpm on 70 mm shafts
Torque. 9,550 × 250 ÷ 1,000 is about 2,390 Nm. With a service factor of 1.5, which we are assuming for this example, design torque is about 3,580 Nm.
Shortlist. EA280 (2,800 Nm nominal) and AG-102 (2,720 Nm) fall short, so we go one size up in each range. EA500 is rated 5,000 Nm nominal with a 25 mm pilot bore and a 75 mm maximum. AG-103 is rated 4,920 Nm, takes 30 to 75 mm bores, and is limited to 5,200 rpm. Both take a 70 mm shaft and clear the torque.
Tie-break. EA500 weighs 14 kg with an A dimension of 171 mm. AG-103 weighs 26 kg with 220 mm. EA500 also lists ±0.5 mm parallel and 2 x 0.75 degrees angular movement; for AG-103 we would supply the figures on request. If the foundation is light or the gap is tight, EA500 looks better. If the layout needs half-flex, AG-103 is the one. Either way, check EA500’s 10,000 Nm maximum against your actual start-up torque before ordering.
Mistakes We See Most Often
- 1. Sizing from motor kW and skipping the service factor.
- 2. Looking at running torque and ignoring peak torque.
- 3. Comparing one range’s maximum torque with the other’s nominal torque.
- 4. Discovering the bore doesn’t fit after the coupling arrives.
- 5. Reading “flexible” as unlimited misalignment.
- 6. Choosing a large size for torque and missing the rpm limit.
- 7. Treating ST and LT as interchangeable.
- 8. Running the coupling short of grease, or with the wrong grease. Both ranges use EP2.
When a Gear Coupling Isn’t the Answer
Gear couplings are torsionally rigid and need lubrication. If the drive needs shock damping, or you want a coupling with nothing to grease, look at pin bush couplings or tyre couplings instead.
What to Send Us for a Recommendation
The more of this you send, the faster we can answer: motor kW and rpm, the driven machine and its duty, both shaft diameters and keyways, the shaft gap, any measured misalignment, space limits, the operating environment, and a photo or nameplate of the existing coupling if you are replacing one.
Send it through our enquiry form, call +91 81002 25530, or write to works@anigears.com. We have made gear couplings since 2007 (more about us), and we bore and key every coupling to your drawing. If you would rather read first, the AniGears Engineering Solutions catalogue has the full tables.