The SWP-D Long Non-Flexible Universal Joint Coupling delivers extended shaft span coverage (Lmin 430–1980 mm) with a fixed-length rigid intermediate body — no telescoping sleeve. With gyration diameters of 160–640 mm and nominal torques of 16–1 250 kN·m at ≤10° fold angle, SWP-D is the preferred solution for fan drives, mining hoists, and long-span pump station drivetrains where shaft positions are fixed and stiffer intermediate body performance is required.
The SWP-D Long Non-Flexible Universal Joint Coupling occupies a specific niche in the SWP family: it combines the extended shaft span of SWP-A with the fixed-length rigid body of SWP-C, delivering long-reach angular compensation without telescoping capability. The result is a coupling optimised for large fan drives, mining hoist drivetrains, and pump station shaft arrangements where shaft positions are permanently fixed, yet the motor-to-load distance exceeds the available range of the short non-flex SWP-C.
The coupling transmits torque via two Hooke's joint assemblies connected by a precision-aligned fixed-length tube. Fold angle compensation of ≤10° is maintained across the full torque range, identical to SWP-A and SWP-C.
Structural advantages of the fixed long tube: Unlike SWP-A, the SWP-D intermediate body carries no internal sliding components — this eliminates the stick-slip friction that occurs in telescoping splines under load, reduces the number of lubrication points, and produces a stiffer torsional characteristic that benefits speed-controlled and vibration-sensitive drives.
Mining hoist drivetrains with drum-to-gearbox distances exceeding SWP-C Lmin values also benefit from SWP-D's extended range, providing angular compensation for foundation settlement without the unwanted axial compliance of telescoping types.
D3 dimension: Like SWP-A and SWP-E, the SWP-D specification includes a D3 dimension (intermediate tube outer diameter), which is relevant for coupling guard and clearance calculations in plant design.
| Type | D (mm) | Tn (kN·m) | Tf (kN·m) | β | Lmin (mm) | D1 js11 | D2 H7 | D3 | E | E1 | b×h | h1 | L1 | n–d | I Lmin (kg·m²) | ΔI/100mm | G Lmin (kg) | ΔG/100mm |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SWP160D | 160 | 16 | 8 | ≤10 | 430 | 140 | 95 | 114 | 15 | 4 | 20×12 | 6 | 85 | 6–13 | 0.09 | 0.0059 | 35 | 2.1 |
| SWP180D | 180 | 20 | 10 | ≤10 | 474 | 155 | 105 | 121 | 15 | 4 | 24×14 | 7 | 95 | 6–15 | 0.16 | 0.0072 | 47 | 2.3 |
| SWP200D | 200 | 31.5 | 16 | ≤10 | 544 | 175 | 125 | 127 | 17 | 5 | 28×16 | 8 | 110 | 8–15 | 0.28 | 0.0114 | 67 | 3.4 |
| SWP225D | 225 | 40 | 20 | ≤10 | 636 | 196 | 135 | 152 | 20 | 5 | 32×18 | 9 | 130 | 8–17 | 0.53 | 0.029 | 94 | 6.6 |
| SWP250D | 250 | 63 | 31.5 | ≤10 | 690 | 218 | 150 | 168 | 25 | 5 | 40×25 | 12.5 | 135 | 8–19 | 0.91 | 0.0407 | 140 | 7.3 |
| SWP285D | 285 | 90 | 45 | ≤10 | 760 | 245 | 170 | 194 | 27 | 7 | 40×30 | 15 | 150 | 8–21 | 1.91 | 0.0702 | 206 | 9.4 |
| SWP315D | 315 | 140 | 63 | ≤10 | 860 | 280 | 185 | 219 | 32 | 7 | 40×30 | 15 | 170 | 10–23 | 3.39 | 0.1144 | 271 | 12.0 |
| SWP350D | 350 | 180 | 90 | ≤10 | 940 | 310 | 210 | 245 | 35 | 8 | 50×32 | 16 | 185 | 10–23 | 5.35 | 0.1663 | 355 | 13.6 |
| SWP390D | 390 | 250 | 112 | ≤10 | 1060 | 345 | 235 | 273 | 40 | 8 | 70×36 | 18 | 205 | 10–25 | 10.54 | 0.2695 | 501 | 18.0 |
| SWP435D | 435 | 355 | 160 | ≤10 | 1180 | 385 | 255 | 299 | 42 | 10 | 80×40 | 20 | 235 | 16–28 | 18.56 | 0.3645 | 825 | 20.0 |
| SWP480D | 480 | 450 | 224 | ≤10 | 1360 | 425 | 275 | 351 | 47 | 12 | 90×45 | 22.5 | 265 | 16–31 | 31.69 | 0.7028 | 1144 | 28.0 |
| SWP550D | 550 | 710 | 315 | ≤10 | 1460 | 492 | 320 | 402 | 50 | 12 | 100×45 | 22.5 | 290 | 16–31 | 51.45 | 1.1842 | 1589 | 35.7 |
| SWP600D | 600 | 1000 | 500 | ≤10 | 1840 | 544 | 380 | 450 | 55 | 15 | 90×55 | 27.5 | 360 | 22–34 | 83.53 | 1.7159 | 2243 | 40.5 |
| SWP640D | 640 | 1250 | 630 | ≤10 | 1980 | 575 | 385 | 480 | 60 | 15 | 100×60 | 30 | 385 | 18–38 | 135.6 | 2.308 | 3140 | 48.3 |
Note: D=315mm, L=900mm → SWP315D×900. All dimensions mm. SWP-D has no Ls column (fixed length). D3 = intermediate tube OD for guard clearance design. ΔI and ΔG are incremental values per 100 mm additional length above Lmin.
Large Industrial Fan Drives — Power & Process Plants
Working condition: High-speed operation (500–1000 rpm), continuous duty, critical service, precise shaft alignment over long spans. Fan shaft and motor shaft separated by gearbox with fixed shaft geometry.
Why SWP-D: The fixed long tube spans the motor-to-gearbox or gearbox-to-fan distance without the sliding friction of telescoping types. The stiffer intermediate body suppresses shaft whip in high-speed service and reduces vibration transmitted to fan bearings.
Customer benefit: Extended fan bearing MTBF versus rigid spacer couplings; measurably lower vibration levels compared to telescoping sleeve types in high-speed service.
⛏️ Mining Hoist Drivetrains — Fixed Drum Geometry
Working condition: Cyclic loading with high peak torques during acceleration, drum position axially fixed by thrust bearing arrangement, extended motor-to-drum shaft span on large winding gear installations.
Why SWP-D: Hoist drum axial position is governed by the drum shaft's dedicated thrust bearing — no axial compliance is desirable in the drivetrain. SWP-D provides angular compensation for foundation settlement across long shaft spans without introducing axial play that could affect drum position accuracy.
Customer benefit: Drum position integrity maintained; no coupling-induced axial loads on drum bearings; lower maintenance frequency compared to telescoping types.
Long-Span Pump Station Drives
Working condition: Remote location, minimal maintenance access, motor and pump separated by large reducer or gearbox with extended shaft spans.
Why SWP-D: Rural and remote pump station drivetrains often have motor-to-pump shaft spans beyond SWP-C Lmin capacity. SWP-D bridges this gap without requiring an intermediate bearing housing, reducing overall drivetrain complexity.
Customer benefit: Single-coupling solution for long spans without intermediate bearing housing; reduced maintenance obligations at remote sites.
⚙️ Rolling Mill Pinion Stands — Auxiliary Line Shafts
Working condition: Long auxiliary line shaft from main gearbox to pinion stand, moderate speed, fixed rolling mill frame geometry.
Why SWP-D: Where the SWP-A's telescoping feature is unnecessary (rolling mill line shaft positions are fixed by the mill housing), SWP-D provides the required long span more efficiently — with lower inertia and no spline maintenance between scheduled overhauls.
Customer benefit: Lower drivetrain inertia improves rolling mill speed response; no spline maintenance required between scheduled overhauls.
The SWP-D is the most frequently misspecified type in the SWP range, primarily because engineers default to SWP-A for any long-span application. The key discriminator is whether axial shaft movement occurs — if not, SWP-D delivers superior performance at lower ongoing maintenance cost.
| Feature | SWP-D (Long Non-Flex) | SWP-A (Long Flex) | SWP-C (Short Non-Flex) | SWP-F (Long Big Flex) |
|---|---|---|---|---|
| Body Length | Long (430–1980 mm) | Long (660–2685 mm) | Short (340–1540 mm) | Long (770–2920 mm) |
| Telescoping (Axial) | ❌ None | ✅ 50–230 mm | ❌ None | ✅ 150–380 mm (large) |
| Angular Capacity | ≤10° | ≤10° | ≤10° | ≤10° |
| Rotational Inertia vs A | Lower (no sleeve) | Reference | Lowest | Higher |
| Lubrication Points | 2 (spiders only) | 3 (spiders + sleeve) | 2 (spiders only) | 3 (spiders + sleeve) |
| Ideal For | Long fixed-span drives | Long spans with axial float | Short fixed-span drives | Long spans, large axial float |
Critical speed check: For SWP-D, the fixed tube acts as a rotating shaft — at long spans, the first critical speed must exceed maximum operating speed by at least a 30% safety factor. verify with our engineering team for spans above 1500 mm.
Foundation settlement allowance: Specify the maximum expected angular misalignment change over the equipment lifetime (foundation settlement, bearing wear, frame distortion). SWP-D accommodates up to ≤10° continuously — design for ≤5° steady state.
⚠️ Critical Mistakes to Avoid with SWP-D
Unsure whether SWP-D or SWP-A is appropriate for your drive? Contact Our Engineers for a detailed drivetrain review.
We manufacture SWP-D couplings to the same JB/T 3241-91 standard as the full SWP family. The long fixed-tube intermediate body receives particular attention in our production process, with additional quality verification steps not required for shorter types.
Tube Straightness & Weld Quality
Intermediate tubes are mandrel-straightened to ≤0.08 mm/m before yoke welding. Post-weld straightness is re-verified by dial indicator sweep. Weld zones undergo magnetic particle inspection to ASTM E709.
⚖️ Precision Dynamic Balancing
All SWP-D assemblies are dynamically balanced to ISO 1940 G6.3 as standard. For customer-specified high-speed applications (>1000 rpm for D160–D225), G2.5 precision balancing is available on request.
Alloy Steel Construction
Yokes: 42CrMo4 alloy steel, quench-tempered, tensile strength ≥900 MPa. Intermediate tube: seamless 45# steel, normalised. Cross-spider: carburised 20CrMnTi, 58–62 HRC case hardness.
Documentation & Compliance
Full material test reports (MTR) for yoke and tube steel provided with every order. Heat treatment charts for spider cross components are available on request. Dynamic balance report issued per ISO 1940.
We replaced a worn flexible disc coupling on our ID fan drive with SWP-D units. The long fixed tube matched our existing shaft-to-shaft distance precisely, and the angular compensation managed the minor misalignment from our fan foundation. Vibration readings dropped significantly after installation.
— Rotating Equipment Engineer, Power Generation Site
Russia — Mining Hoist Drivetrain, Siberian Mine ★★★★★
We installed SWP480D couplings on a modernised mine hoist drivetrain. The non-flex design was essential to maintain drum axial position integrity — our drum shaft thrust bearings are not designed to absorb coupling-induced axial loads. Excellent engineering and reliable supply.
— Chief Mechanical Engineer, Siberian Mining Operation
China — Rolling Mill Line Shaft, Jiangsu Province ★★★★☆
SWP315D used on auxiliary line shafts in a bar mill upgrade. The lower inertia compared to the previous SWP-A units improved our motor acceleration response, reducing roll gap engagement time. Good quality; would specify again.
— Mechanical Project Engineer, Jiangsu Rolling Mill Operator
Indonesia — Water Pump Station, Kalimantan ★★★★★
Remote pump station at a mine site. We needed a long-span coupling with minimal maintenance requirements. SWP-D was the right choice — two spider re-greases per year is all this coupling needs. Running 24 hours a day, no failures in two years.
— Operations Manager, Kalimantan Mining Pump Station
Both SWP-A and SWP-D are long-body types with the same angular compensation capacity (≤10°) and identical torque ratings at each diameter. The fundamental difference is the presence of a telescoping sleeve in SWP-A and its absence in SWP-D. Choose SWP-A when axial shaft movement must be accommodated; choose SWP-D when shaft positions are fixed and a stiffer, lower-maintenance drivetrain is preferred.
Yes, provided you verify two things: (1) no axial shaft movement occurs in the application — if the SWP-A was being used to absorb thermal growth or roll change extraction, replacing it with SWP-D will transmit axial forces directly to connected bearings; (2) the SWP-D Lmin for your selected size is achievable within your existing shaft-to-shaft distance.
Maximum permissible speed depends on gyration diameter and tube span. Approximate limits: D160–D200: ≤2000 rpm; D225–D285: ≤1500 rpm; D315–D390: ≤1000 rpm; D435–D480: ≤750 rpm; D550–D640: ≤500 rpm. For higher speeds or long spans, request a critical speed calculation from our engineering team.
SWP-D has fewer lubrication points than SWP-A — only the two cross-spider needle bearing assemblies require greasing; there is no telescoping spline to maintain. Recommended lubrication interval: every 800–1200 operating hours under normal conditions. Use NLGI #2 lithium-complex grease rated to the ambient temperature range of your application.
Yes. SWP-D carries the same fatigue torque (Tf) as equivalent SWP-A and SWP-B sizes — this is the governing parameter for reversing or shock-load applications. For hoist applications with full torque reversal during lowering cycles, verify that your peak torque does not exceed Tf for your selected size.
Fan drives, mining hoists, long-span pump stations — wherever extended shaft coverage without axial compliance is required, SWP-D delivers. Share your torque requirement, shaft span, and operating speed with our team for a sizing recommendation.
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ISO 9001:2015 · Industrial Fan & Mining Hoist Supply Experience
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