Reuland / Trilex RC Flexible Shaft Couplings
Aluminum jaw-type flexible shaft couplings in sizes RC1 to RC8, bores 3/8" to 3-7/8", with a black L9 or blue H5 Hytrel® insert. Original Reuland stock and new Trilex couplings to the same design; many sizes ship from stock, others are made to order.
RC1 to RC8
Eight sizes, 180 standard bore and keyway combinations from 0.375" to 3.875".
Two Hytrel inserts
Black L9 for standard duty, blue H5 for severe duty and higher torque.
Up to 47,269 lb-in
Rated torque of an RC8 with the H5 insert.
Stock and to order
Original Reuland stock plus new Trilex production.
Sizes, bores and ratings
Dimensions in inches. The shaft must not exceed the coupling's maximum bore (the top of the bore range).
| Size | Bore range (in) | Keyway range (in) | OD × length (in) | Rated torque, lb-in L9 / H5 |
Insert |
|---|---|---|---|---|---|
| RC1 | 0.375 – 1.125 | 0.093 – 0.250 | 2.62 × 2.56 | 473 / 630 | RG1-L9 or H5 |
| RC2 | 0.375 – 1.375 | 0.093 – 0.375 | 2.91 × 3.17 | 630 / 1,103 | RG2-L9 or H5 |
| RC3 | 0.500 – 1.625 | 0.125 – 0.375 | 3.44 × 3.60 | 1,261 / 2,206 | RG3-L9 or H5 |
| RC4 | 0.625 – 1.875 | 0.125 – 0.500 | 4.00 × 4.24 | 1,576 / 3,309 | RG4-L9 or H5 |
| RC5 | 0.750 – 2.375 | 0.187 – 0.625 | 4.81 × 4.68 | 3,466 / 6,933 | RG5-L9 or H5 |
| RC6 | 0.750 – 2.625 | 0.187 – 0.625 | 5.97 × 6.04 | 7,563 / 15,756 | RG6-L9 or H5 |
| RC7 | 1.125 – 2.875 | 0.250 – 0.750 | 6.91 × 7.01 | 12,605 / 28,361 | RG7-L9 or H5 |
| RC8 | 1.250 – 3.875 | 0.250 – 1.000 | 8.62 × 7.92 | 31,513 / 47,269 | RG8-L9 or H5 |
OD = coupling outside diameter; length = overall length of the assembled coupling. Ratings are for the complete coupling. Bore tolerance: +0.0008/+0.0003" up to 1"; +0.0013/+0.0005" to 2"; +0.0018/+0.0008" to 3"; +0.0020/+0.0010" to 3.875". Per Reuland and Trilex RC coupling data.
How to select an RC coupling
1. Service factor
Find your load and prime mover in the table below. With an electric motor: 1.0 for light, steady loads, 1.5 for moderate shock, 2.0 for heavy shock.
2. Rated torque
Rated torque (lb-in) = (HP × 63,000 ÷ RPM) × service factor.
Example: 10 HP at 1,750 RPM with a 1.5 service factor: 10 × 63,000 ÷ 1,750 = 360 lb-in; × 1.5 = 540 lb-in.
3. Shaft size
Check both shafts. Neither may exceed the coupling's maximum bore; the two hubs can have different bores.
4. Select the size
Choose the smallest size whose rated torque covers yours and whose bore range takes both shafts, then the insert. Not sure? Send the numbers and we will size it.
Service factors
| Load | Electric motor or turbine | Engine, 6 or more cylinders | Engine, under 6 cylinders |
|---|---|---|---|
| Light: even, steady, non-reversing (blowers, centrifugal pumps, agitators, conveyors, fans) | 1.0 | 1.5 | 2.0 |
| Moderate: moderate shock, uneven, infrequent reversing (elevators, mixers, machine tools, reciprocating pumps) | 1.5 | 2.0* | 2.5* |
| Heavy: heavy shock, uneven, frequent reversing (shaker conveyors, crushers, winches, presses) | 2.0* | 2.5* | 3.0* |
* Use the blue H5 Hytrel insert. Per the Reuland coupling selection guide.
L9 or H5 insert?
| Insert | Material | Service factor | Temperature |
|---|---|---|---|
| L9 (black) | Hytrel®, 34D | Up to 1.5 | −30 to 175 °F |
| H5 (blue) | Hytrel®, 50D | Above 1.5; severe duty | −60 to 250 °F |
The H5 gives the higher torque rating in the size table. Reuland's catalog rates parallel misalignment at 0.015", and angular misalignment at up to 1° with its standard insert and 0.5° with Hytrel. Trilex may mark the blue insert H9. Per Reuland / Trilex RC coupling literature.
Related: Reuland motors and pump adapters, chain, sprockets and sheaves, gearboxes.
Reuland / Trilex coupling FAQ
What is the difference between a Reuland and a Trilex coupling?
In 2025 Reuland Electric sold its flexible coupling inventory to a small group of distributors, including Jealco, and transferred the drawings and manufacturing rights to Trilex Fluid Power, which now makes the RC line. We still have original Reuland stock and also supply Trilex couplings to the same design and specifications. Fit and performance are the same; only the name on the part may differ.
If I order a Reuland coupling, could I receive a Trilex one?
It is possible, depending on stock. The Trilex coupling is made to the same design, and we have had no fit or performance issues with it. If you need original Reuland-marked stock, tell us when you order and we will confirm availability.
What makes up a complete coupling?
Two coupling halves of the same RC size and one grommet (insert) for that size: an RC3 coupling takes two RC3 halves and one RG3 grommet. The two halves can have different bores to join two different shafts.
How do I select the right coupling size?
Pick the service factor for your load and prime mover (1.0 to 3.0), calculate rated torque as HP times 63,000 divided by RPM, times the service factor, check that neither shaft exceeds the coupling's maximum bore, and choose the smallest RC size whose rated torque covers it. Send us the numbers if you would like us to size it.
Which insert should I choose, L9 or H5?
Both are Hytrel. The black L9 (34D) suits service factors up to 1.5 and temperatures from -30 to 175 F. The blue H5 (50D) is for severe duty and service factors above 1.5, from -60 to 250 F, and gives the higher torque rating. Trilex may mark the blue insert H9.
Which sizes and bores are available?
Sizes RC1 through RC8, with 180 standard bore and keyway combinations from 3/8 inch (RC1 and RC2) up to 3-7/8 inch (RC8). Many ship from stock; others are made to order. Metric bores, splined hubs and special keyways are quoted to order.
Can I buy couplings online?
Yes. Every standard coupling half, by size and bore, and both inserts for every size are in our online store. For other bores, splines, metric bores or quantity orders, contact us.
Send the size, both bores and the insert
Or send the motor HP and RPM, the load type and the shaft sizes, and we will size the coupling for you.