The RP-S Double Elastomer Jaw Flexible Coupling uses a three-part, double-section design that compensates for large installation misalignments while damping vibration and minimising stress on adjacent components. Maximum torque 2,400 N·m; maximum bore Φ100 mm; angular compensation 1.5°.
Where installation conditions make precise shaft alignment difficult or where thermal growth introduces significant misalignment during operation, the RP-S Double Elastomer Jaw Flexible Coupling provides a robust engineering answer. Its three-part, double-section architecture places two independent polyurethane elastomeric elements in series between the driving and driven hubs. This arrangement multiplies the angular and axial compensation capacity compared with a single-element coupling and dramatically reduces the reaction forces transmitted to shaft bearings and adjacent gearboxes.
The double elastomer design also provides improved vibration damping across a broader frequency band, since each elastomeric stage attenuates a different portion of the vibration spectrum. Operating noise is correspondingly lower than in equivalent single-element designs. Because the intermediate spacer body separates the two elastomeric zones, the RP-S can accommodate relatively large axial displacement without generating significant axial bearing loading. The marking convention is the same as for the RP-A, allowing direct size cross-reference between the two series. Standard elastomer hardness is 92 ShA; 98 ShA elements may also be fitted to the same hubs when higher torque capacity is required.
| Model | Torque (N·m) | Speed (rpm) | Bore d (mm) | D (mm) | E (mm) | Radial comp. (mm) | Axial comp. (mm) |
|---|---|---|---|---|---|---|---|
| RP19S | 10 | 19000 | 6–25 | 40 | 16 | 0.65 | 1.2 |
| RP24S | 35 | 14000 | 8–35 | 55 | 18 | 0.89 | 1.4 |
| RP28S | 95 | 11800 | 10–40 | 65 | 20 | 1.00 | 1.5 |
| RP38S | 190 | 9500 | 12–48 | 80 | 24 | 1.15 | 1.8 |
| RP42S | 265 | 8000 | 14–55 | 95 | 26 | 1.26 | 2.0 |
| RP48S | 310 | 7100 | 15–60 | 105 | 28 | 1.36 | 2.1 |
| RP55S | 410 | 6300 | 20–70 | 120 | 30 | 1.52 | 2.1 |
| RP65S | 625 | 5600 | 22–75 | 135 | 35 | 1.75 | 2.6 |
| RP75S | 1280 | 4750 | 30–60 | 160 | 40 | 2.00 | 3.0 |
| RP90S | 2400 | 3750 | 40–100 | 200 | 45 | 2.50 | 3.4 |
Angular compensation: 1.5° for all models. All values for 92 ShA elastomers.
The RP-S is the preferred coupling wherever shaft alignment cannot be held to tight tolerances, or where vibration isolation between the driver and driven machines is a key requirement. Representative applications include:
For flanged connections to heavy machinery, consider the RP-SF/RP-DF single and double flange jaw coupling. See the complete coupling portfolio for all options.
🇳🇱 Netherlands — Gas Engine Generator Set
A combined heat and power plant operator in Groningen replaced single-element couplings on four 450 kW gas engine-generator units with RP-S couplings. Measured vibration velocity at the generator bearing housing fell by 62 %, and generator bearing replacements have been eliminated entirely in two years of operation.
★★★★★
"The improvement in generator reliability paid back the coupling cost within three months." — Operations Manager
🇨🇿 Switzerland — Precision Pump OEM
A pump manufacturer near Zürich specified RP-S couplings across a chemical dosing pump range where motor-to-pump misalignment varied between installations. The double elastomer design eliminated seal failures that had been attributed to shaft radial loading from misaligned couplings.
★★★★★
"Seal replacement intervals extended from six months to well beyond two years." — Engineering Manager
🇸🇪 Sweden — Industrial Ventilation
An industrial ventilation contractor in Gothenburg installed RP-S couplings on large fan drives in a steel processing plant. The couplings absorbed the vibration and thermal expansion of the duct system, and acoustic measurements confirmed a reduction in transmitted structure-borne noise to adjacent offices.
★★★★☆
"Straightforward to install and the noise improvement was immediately noticeable." — Site Foreman
The double-section architecture of the RP-S approximately doubles the permitted radial and axial compensation values for a given size, while the angular limit of 1.5° applies to both types. The real advantage of the RP-S lies in its ability to accommodate radial offsets and axial displacements that would generate damaging bearing loads in a single-element coupling.
Yes. The intermediate spacer body sits between the two hub-and-spider assemblies. With the drive isolated, the spacer and both spiders can be removed radially or axially — depending on the space available — and new elements fitted without the need to move either hub axially along its shaft. Always verify there is adequate working clearance before starting the procedure.
Thermal expansion misalignment is one of the primary design targets of the RP-S. When the driver and driven machine operate at significantly different temperatures — for example a cold-start diesel engine coupled to a warm generator — differential expansion creates progressive radial offset during warm-up. The RP-S accommodates this without generating harmful bearing loads or elevated coupling wear.
The angular compensation limit is 1.5° for all RP-S models, consistent across the entire size range from RP19S to RP90S. Note that this limit applies to the total angular misalignment across the coupling; in a double-section design each elastomeric stage accommodates approximately half the total angle.
A single elastomeric coupling generates a radial restoring force proportional to the shaft offset. By placing two elastomeric stages in series through an intermediate body, the restoring force on each shaft bearing is approximately halved for the same total radial offset. This reduction in bearing radial load directly extends L10 bearing life — theoretically by a factor approaching eight if the bearing life equation is applied, because bearing life varies inversely with the cube of the applied radial load.
RP supplies the RP-S to drive system OEMs, engineering contractors, and industrial distributors. Custom bore specifications, special elastomers, and technical support for selection calculations are available. Visit the jaw coupling section for the full range or the coupling catalogue for a broader selection.
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