SWC-DH Short Flex Welding Type Universal Coupling

Buy SWC-DH Short Flex Welding Type Universal Coupling from a Chinese Manufacturer

Procurement engineers usually arrive here with three numbers already fixed: shaft bore, centre-to-centre distance and peak torque. SWC-DH was developed for exactly that situation. Where a standard SWC-BH standard flex welding type universal coupling needs extra axial room for its longer flex, the short-flex DH version removes that length while keeping the same torque capacity — so you can fit a heavy-duty cardan shaft into a mill stand, a hoist drum or a crane trolley without redesigning the surrounding frame.

Raydafon manufactures the complete SWC series, from this compact DH coupling up to the long-extension SWC-CH long flex welding type universal coupling, under an ISO 9001 quality system. One engineering contact follows your RFQ from drawing check to delivery, and the same team handles repeat orders, so specification drift between batches is not something you have to police.

What Is a Short Flex Welding Type Universal Coupling?

A short flex welding type universal coupling is a cardan-type joint whose two yokes are welded directly onto the driving and driven shafts, with the smallest possible flex length between the trunnions. The welding connection removes the need for flanges, keys or clamping hubs, which both shortens the assembly and eliminates a common source of backlash. Because the flex section is short, the coupling tolerates angular misalignment up to 25° and small axial and radial offsets, but it resists axial displacement — the design choice that makes rolling-mill and hoist drives so reliable.

In this DH series the gyration diameter runs from φ180 mm to φ390 mm and rated torque from 20 kN·m to 250 kN·m. If your duty cycle points beyond that, the SWC-WF flange type universal coupling covers the same series in a bolt-on variant, and the wider SWC family reaches 1000 kN·m — Raydafon can quote either from the same factory.

Technical Specifications and Size Selection

• Model rangeSWC180DH1 – SWC390DH2
• Gyration diameter Dφ180 / φ225 / φ250 / φ285 / φ315 / φ350 / φ390 mm
• Nominal torque Tn20 – 250 kN·m
• Fatigue (alternating) torque Tf≤25 kN·m (SWC180DH) to ≤15 kN·m (SWC390DH)
• Axis fold angle β10° / 15° / 20° / 31.5° / 45° / 63° / 90° / 125° per size
• Flex quantity Ls40 / 55 / 70 / 80 / 90 / 100 / 120 / 130 / 140 / 150 mm
• Cross shaftAlloy steel, chrome plated
• Yoke material35CrMo forged steel, integrated fork head
• Bearings4 × needle bearing sets per joint
• Bolted flange options (D1/D2)φ105 – φ235 mm (js11 / H7)
• Custom optionsBore, keyway, length, spline, stainless or painted finish

• Tf — the torque permitted under alternating load, calculated from fatigue strength.
• Lmin — the minimum length after the cut; the installed length L is made to your requirement.
• D1 (js11) / D2 (H7) — optional bolted flange bores. The welding-type yoke is supplied unbored for welding onto your shaft.
• Tolerances and dimensions follow the SWC series standard. Need a non-standard L, bore or spline? Send the drawing and we will confirm feasibility with the quotation.

Product Detail

The photographs below are our own production parts — forged fork head, machined flange face, welded yoke and the needle-bearing trunnion that carries the load.

How to Choose the Right SWC-DH Size

1. Fix the bore and connection first. Confirm shaft diameter and keyway, or the D1/D2 flange bore and bolt pattern from the table above. If the shaft is splined or tapered, tell us — it changes the yoke, not the torque rating.
2. Compare torque, not size. Select the model whose nominal torque Tn exceeds your peak running torque with your normal service factor. For reversing or shock-loaded drives, check Tf as well: it is the fatigue limit under alternating load.
3. Measure the space. The DH series exists to save length. Compare Lmin against the gap you actually have, and remember that Ls indicates how much of that length is flex.
4. Declare the working angle. Every model has its own β limit (see the β column). Operating continuously at a large angle raises the equivalent torque on the bearings, so a size up is often cheaper than a premature failure.
5. Send the RFQ. Include model or drawing, quantity, shaft material, working angle and delivery port. We reply with a firm price and lead time — usually within 24 hours.

Materials, Machining and Quality Control at Raydafon

The yoke is forged from 35CrMo and machined as an integrated fork head rather than a bolted assembly. That single change removes the bolted joints that typically loosen first on a cardan shaft, and it raises overall structural strength by roughly 30–50% compared with split designs. The cross shaft is alloy steel, hardened at the journal and chrome plated to resist corrosion and fretting in dusty or humid plant environments.

Each joint carries four needle bearing sets with controlled fit clearance, which is where the low noise and the 98.6% transmission efficiency come from. Before dispatch we check bore and keyway dimensions, run-out, hardness and assembled articulation; test reports and material certificates are issued with the shipping documents when your project requires them.

Why Buyers Choose This Coupling

• High torque in a short body
• Up to 25° misalignment compensation
• 98.6% transmission efficiency
• 30–40 dB(A) operating noise
• Chrome-plated cross shaft
• Integrated fork head, no loose bolts
• ISO 9001 factory
• OEM & custom bore available

Operator feedback on vibration and noise is consistently positive: with the bearings correctly fitted and greased, measured noise stays in the 30–40 dB(A) range, which keeps the coupling suitable for enclosed workshops and food or electronics plants as well as heavy industry.

Applications

SWC-DH couplings are specified wherever a short, high-torque shaft connection has to survive continuous duty:

• Rolling millsMain drive and roller table shafts
• Hoists and cranesDrum drives, trolley and slewing gear
• Metallurgical plantContinuous casters, shears, run-out tables
• Mining machineryConveyors, crushers, screening drives
• Construction equipmentMixers, piling rigs, heavy winches
• Marine & portWinch and berth machinery drives

If your machine is not on this list, tell us the application and duty cycle. Heavy-machinery drives are rarely identical, and a coupling that suits a steel mill may need a different bore, balance grade or grease specification for a crane duty.

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