The SWP-G Super Short Flexible Universal Joint Coupling is the most compact variant in the SWP family (Lmin 435–715 mm), covering gyration diameters 225–350 mm and torques 18–71 kN·m at a reduced fold angle of ≤5°. It is engineered for food processing machinery, chemical reactor drives, compact conveyor drives, and industrial pump skids where available installation length excludes all other SWP types and shaft alignment can be maintained within the tighter angular limit.
The SWP-G Super Short Flexible Universal Joint Coupling is the most compact member of the SWP family — built for installations where even the short-body SWP-B or SWP-C is too long to fit. With an overall installed length (Lmin) of just 435–715 mm across the D225–D350 diameter range, SWP-G delivers the angular compensation and in-situ spider replacement capability of the SWP series in the smallest available envelope.
The compactness comes with two important constraints that set SWP-G apart from all other SWP types: fold angle is restricted to ≤5° (versus ≤10° for types A–F), and the available size range covers only five diameters (D225–D350, torques 18–71 kN·m). SWP-G is not a general-purpose replacement for other SWP types — it is specifically for applications where length is the binding constraint and alignment can be held to within 5°.
Structural distinction — D0 centre column: The SWP-G specification includes a D0 column (centre diameter) not present in other SWP types. This dimension defines the outside diameter of the compact centre body — critical for coupling guard design and installation clearance verification.
Telescoping stroke: SWP-G provides Ls of 40–55 mm (D225–D350), proportional to its compact dimensions. This moderate stroke is sufficient for the assembly tolerance and thermal compensation requirements typical of the close-coupled applications for which SWP-G is designed.
Critical design check — fold angle: Because SWP-G is limited to ≤5° fold angle, shaft alignment must be tighter than for SWP-A through SWP-F. Before specifying SWP-G, verify that your installation can achieve and maintain ≤5° angular misalignment under all operating conditions including thermal growth, foundation settlement, and bearing wear.
| Type | D (mm) | Tn (kN·m) | Tf (kN·m) | Ls (mm) | β | Lmin (mm) | D0 | D1 js11 | D2 H7 | E | E1 | b×h | h1 | L1 | n–d | I Lmin (kg·m²) | G Lmin (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SWP225G | 225 | 18 | 8 | 40 | ≤5 | 435 | 275 | 248 | 135 | 15 | 5 | 32×18 | 9 | 68 | 10–15 | 0.331 | 60 |
| SWP250G | 250 | 25 | 11.2 | 40 | ≤5 | 515 | 305 | 275 | 150 | 15 | 5 | 40×25 | 12.5 | 80 | 10–17 | 0.624 | 97 |
| SWP285G | 285 | 35.5 | 16 | 40 | ≤5 | 565 | 348 | 314 | 170 | 18 | 7 | 40×30 | 15 | 90 | 10–19 | 1.182 | 120 |
| SWP315G | 315 | 50 | 25 | 40 | ≤5 | 620 | 360 | 328 | 185 | 18 | 7 | 40×30 | 15 | 100 | 10–19 | 2.29 | 170 |
| SWP350G | 350 | 71 | 35.5 | 55 | ≤5 | 715 | 405 | 370 | 210 | 22 | 8 | 50×32 | 16 | 108 | 10–21 | 3.793 | 256 |
Note: D=315mm, L=620mm → SWP315Gx620. SWP-G is restricted to 5 sizes (D225–D350) and fold angle ≤5°. D0 = compact centre body OD (unique to SWP-G). Lmin values (435–715 mm) are the shortest in the SWP family.
Food Processing & Packaging Machinery Drives
Working condition: Compact machine footprint, moderate torque (18–71 kN·m covers most packaging and conveying drives), hygiene-sensitive environment requiring minimal lubricant leakage risk.
Why SWP-G: Food processing plant designers specify the smallest possible coupling envelope to maximise product flow clearance and simplify machine guarding. SWP-G's 435–715 mm overall length fits within machine frame dimensions that exclude all other SWP types.
Customer benefit: Compact drivetrain fits existing machine bay dimensions without frame modification; minimal lubricant exposure risk with correct sealing; angular compensation to ≤5° handles conveyor and drive frame flex.
Chemical & Pharmaceutical Reactor Drives
Working condition: Process equipment in confined plant areas, moderate shaft misalignment from reactor settlement, requirement for angular compensation without flexible elastomeric elements.
Why SWP-G: Reactor agitator and mixer drives in chemical plants often require angular compensation while excluding elastomeric coupling elements due to particle shedding risk. SWP-G's all-metal construction satisfies this requirement in a compact body.
Customer benefit: Compatible with elastomer-free process area requirements; compact body suits existing drive arrangements; spider replacement during turnarounds without frame disassembly.
Material Handling — Short Centre Distance Conveyor Drives
Working condition: Short motor-to-drive-shaft centre distances in compact conveyor frames, moderate torque, ambient dust exposure.
Why SWP-G: Compact conveyor frames in industrial settings. SWP-G's 435–715 mm Lmin covers these close-coupled arrangements without mechanical modification to the frame.
Customer benefit: Standard conveyor frame dimensions maintained; no shaft extension required; angular compensation accommodates conveyor frame flex under load.
⚙️ Light Industrial Pump & Compressor Drives
Working condition: Mid-range torque (18–71 kN·m), moderate speed, restricted installation space between prime mover and pump/compressor, well-controlled shaft alignment (≤5° achievable).
Why SWP-G: Pump and compressor skid designers in industrial settings. SWP-G enables spider-type universal joint coupling benefits in close-coupled skid layouts where longer types cannot fit.
Customer benefit: Universal joint angular compensation in a compact skid without the footprint penalty of longer SWP types; all-metal construction compatible with process plant temperature requirements.
SWP-G is a highly specialised type within the SWP family. Before specifying it, two absolute requirements must be confirmed: (1) installation length is truly insufficient for SWP-B or SWP-C; (2) shaft alignment can be held to ≤5° under all operating conditions.
| Parameter | SWP-G (Super Short) | SWP-B (Short Flex) | SWP-C (Short Non-Flex) |
|---|---|---|---|
| Min Overall Length (D225) | 435 mm | 830 mm | 520 mm |
| Min Overall Length (D315) | 620 mm | 1120 mm | 680 mm |
| Fold Angle Limit | ≤5° | ≤10° | ≤10° |
| Axial Telescoping | ✅ Yes (40–55 mm) | ✅ Yes (50–230 mm) | ❌ None |
| Size Range | D225–D350 only | D160–D640 | D160–D640 |
| Torque Range | 18–71 kN·m | 16–1250 kN·m | 16–1250 kN·m |
| Best Use Case | Ultra-compact, ≤5° offset | Compact with moderate offset | Compact, fixed shaft, ≤10° offset |
The 5° limit of SWP-G is a firm design constraint, not a conservative guideline. Exceeding 5° continuous operating angle causes accelerated spider bearing wear and introduces a cyclic velocity variation (Hooke's joint second-harmonic effect) that generates unacceptable vibration levels in close-coupled machinery.
⚠️ Critical Errors When Specifying SWP-G
Is SWP-G the right choice for your compact drive application? Contact Our Engineers — share your available installation length and angular misalignment data and we will verify whether SWP-G meets your requirements.
We manufacture SWP-G to the same JB/T 3241-91 standard as the full SWP family, with specific attention to the compact centre body geometry that defines this type's unique characteristics.
Compact Precision Engineering
The SWP-G centre body (D0) is machined to tighter straightness and runout tolerances than longer SWP types, because any body bow directly impacts the coupling's velocity transmission uniformity at the short spans involved.
⚖️ Balance to G6.3
All SWP-G assemblies are dynamically balanced to ISO 1940 G6.3 as standard — the same balance grade as larger SWP types, which is proportionally more demanding at the shorter body lengths of SWP-G.
Material Specifications
Yokes: 42CrMo4 alloy steel, quench-tempered. Spider crosses: 20CrMnTi, case-hardened 58–62 HRC. Centre body: seamless 45# steel tube, normalised. Flange faces: ground to Ra ≤1.6 μm.
Stock & Lead Time
SWP-G is available in all five standard sizes (D225–D350) with semi-finished yoke stock maintained for rapid assembly. Standard lead time: 10–15 business days. Given the limited size range, we recommend maintaining at least one spare assembly per size in critical applications.
We needed a compact coupling for a new conveyor drive in our food processing line. Our frame allowed a maximum coupling length of 580 mm — SWP-B was too long for our frame and we were about to fabricate a custom extension. SWP-G at 560 mm was the solution. Fitted perfectly, running 18 months without issue.
— Mechanical Engineer, Food Processing Facility
Germany — Chemical Reactor Agitator Drive, Rhine Valley ★★★★★
We replaced elastomeric jaw couplings on our reactor agitator drives with SWP285G units following recurring elastomer particle contamination events. The all-metal spider type eliminated the contamination issue and provided the angular compensation we needed. Running 22 months with no issues.
— Process Engineer, German Chemical Plant
Singapore — Compact Pump Skid Drive ★★★★☆
SWP315G specified for a close-coupled pump skid in a refinery unit. The 620 mm overall length fit our skid design with 8 mm clearance to the guard — very tight but it worked. Coupling performance has been excellent; no vibration issues at 1480 rpm operating speed.
— Skid Design Engineer, Singapore Industrial Equipment Supplier
Italy — Packaging Machinery Drive ★★★★★
We tested RP SWP-G against our incumbent coupling supplier for our new packaging machine line. RP quality was equivalent, dimensional accuracy identical, and price 18% lower. We will continue with RP for future machine builds.
— Purchasing Director, Italian Packaging Machinery Manufacturer
The SWP-G size range is restricted to D225–D350 in the JB/T 3241-91 standard because the super short body design is most commercially and technically viable in this mid-range torque band. Very small SWP types (D160–D200) have Lmin values already short enough that a separate super-short variant offers no significant length saving.
SWP-G can replace jaw or disc couplings in applications where: (1) shaft misalignment is within ≤5° angular; (2) torque is within 18–71 kN·m (SWP225G–SWP350G); (3) installation length is within 435–715 mm (corresponding SWP-G Lmin); and (4) operating speed is within the SWP-G dynamic balance rating.
SWP-G requires more precise shaft alignment than longer SWP types due to its ≤5° fold angle limit. Installation alignment target: angular misalignment ≤3° (to preserve margin below the ≤5° operating limit). Use laser alignment equipment for initial setup.
Both types use the Hooke's joint (universal joint) mechanism, which inherently produces a cyclic variation in output shaft angular velocity relative to input when operated at a fold angle. For SWP-G at ≤5° this variation is small and acceptable for most industrial applications. If constant velocity output is essential, a double-cardan or CV joint arrangement is required — which is outside the SWP standard range.
The standard SWP-G is dynamically balanced to ISO 1940 G6.3, which supports operating speeds up to approximately: D225G ≤2000 rpm; D250G ≤1800 rpm; D285G ≤1500 rpm; D315G ≤1200 rpm; D350G ≤1000 rpm. For higher speeds, upgraded G2.5 balancing is available on request.
When installation space is the primary design constraint and standard short-body couplings cannot fit, SWP-G delivers spider-type universal joint performance in the most compact envelope available in the SWP family. Send us your installation length limit and we will verify compatibility.
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