Description
SL340 Heavy-Industrial Cross-Slider Oldham Coupling — 340 mm Cast-Iron Hub for Primary Mill and Heavy Steel-Plant Drives
The SL340 industrial Oldham coupling moves the SL family into the territory of true primary-process industrial duty. With 20 000 N·m rated torque, 340 mm hub OD, single-bore 150 mm specification, and 100 r/min permissible speed, the SL340 transmits approximately 210–260 kW of continuous mechanical power. This duty class includes primary mining-mill main drives, large cement-kiln main inputs, heavy steel-plant auxiliary lines, primary minerals-processing slurry-pump main drives, and the heaviest end of metallurgical-process mixer outputs. The SL340 is unambiguously a strategic asset — specified after multi-discipline engineering review, integrated into the plant’s risk-management and reliability-engineering documentation, and expected to remain in service for the entire installed life of the host equipment.
A detail worth noting at the SL340: the bore catalogue drops to a single value (150 mm) rather than offering a 5–10 mm range. This reflects the standardisation around the IEC IM B3 large-frame motor output shaft and the typical primary-mill reduction-input shaft, both of which converge on 150 mm at this duty class. For installations requiring non-standard bore dimensions (e.g., 145 mm or 155 mm), engineering can release custom-bore variants under standard custom-build protocols, but the catalogue-standard 150 mm covers the substantial majority of installations at this power level.
Specifications
| Parameter | Value |
|---|---|
| Model | SL340 |
| Nominal Torque (Tn) | 20 000 N·m |
| Permissible Speed (n) | 100 r/min |
| Bore (d) | 150 mm |
| Outside Diameter (D) | 340 mm |
| Hub Bore Diameter (D₁) | 210 mm |
| Overall Length (L) | 250 mm |
| Slider Plate Thickness (H) | 48 mm |
| Slider Clearance (S) | 1.0 mm |
| Moment of Inertia | 8.4 kg·m² |
| Mass | 162 kg |
| Radial Misalignment (Δy) | 6.0 mm |
| Angular Misalignment (Δα) | 0.5° |
| Axial Misalignment (Δx) | 5.0 mm |
| Shaft Engagement | Taper-bushed standard |
| Lubrication | Grease (re-pack 6-monthly) |
Materials
QT500-7 / QT600-3 Hub Options
Catalogue standard is QT500-7 ductile-iron with stress-relief annealing. For primary mining-mill and steel-plant applications, QT600-3 cast-steel hub variant is the engineering-preferred specification — its higher tensile strength (600 MPa) and superior fracture toughness deliver substantial margin against the routine shock-load events of primary-process duty. Each hub masses approximately 75 kg.
48 mm Heavy Hardened Slider
48 mm thick induction-hardened 45-steel cross-slider standard; 40Cr alloyed-steel slider for reversal-duty and high-abrasive deployments. Slider masses approximately 22 kg with pre-machined lifting-eyelet provisions standard. For severe abrasive-environment installations, a hardfaced slider variant with localised tungsten-carbide deposit on the wear faces is offered through engineering review.
Taper-Bushed Mounting Only
At the SL340 size, taper-bushed mounting via standard locking-assembly families (typically Trantorque GT, RINGFEDER 7012, or KTR-Clampex) is the only mounting option supported by engineering. The keyway-mount variant is no longer offered at this size class — the shock-load profile of primary-process duty unambiguously favours the locking-assembly architecture, and engineering does not recommend keyway mounting at 20 000 N·m and above.
Primary-Process Engineering Considerations
At the SL340’s size class, every aspect of the engineering specification matters more than at smaller sizes. The 162 kg coupling mass requires hoist support during installation. The 8.4 kg·m² moment of inertia contributes measurably to the host motor’s effective load profile. The 20 000 N·m torque rating, while comfortable for the cross-slider architecture, sits in the duty class where coupling failure has substantial downstream consequences — typically equipment damage, production-line stoppage, and a multi-shift restart sequence. The specification choice is therefore reviewed by multi-discipline engineering at substantial depth.
The SL340’s design addresses each of these concerns through specific architectural choices. The QT500/QT600 hub material is selected for shock-load endurance rather than minimum cost. The 48 mm slider thickness provides substantial fatigue margin against routine 1.5–2× rated-torque events. Taper-bushed mounting eliminates keyway shear as a failure mode. Pre-machined lifting eyelets simplify hoist-supported installation. And the FMEA documentation supports the reliability-engineering review that any major-equipment specification at this scale must pass. The cumulative effect is a coupling that has earned its place on primary-process equipment specifications across multiple decades — and that maintains that position against newer competing flexible-coupling architectures on lifecycle-cost economics.
For broader engineering background on primary-process coupling selection, see Ever-power’s primary-process engineering portal.
Industry Applications
⛰️ Primary Mining-Mill Main Drives
Main-drive input couplings on primary ball mills, SAG mills, and rod mills in major minerals-processing operations. Slow-speed envelope and substantial misalignment tolerance align with the engineering profile of primary mill duty.
Cement-Kiln Main Inputs
Drive coupling between motor and main reduction-input of large cement-kiln rotating-section drives. Misalignment tolerance absorbs kiln-shell thermal expansion across full burner-zone temperature gradients.
Steel-Plant Heavy Auxiliary
Heavy auxiliary drives in hot-strip mills, bar mills, and continuous-caster cooling-water pump trains. Cast-iron and steel material specification operates at full performance across the elevated-ambient temperatures of steel-plant operation.
Primary Slurry-Pump Main
Main drive coupling on primary slurry pumps in minerals-processing, tailings-management, and dredging applications. QT500/QT600 hubs and 40Cr alloy slider survive aggressive slurry ambient.
Marine Heavy-Cargo Cranes
Slewing and luffing drives on heavy-lift marine cranes and offshore-supply vessel deck equipment. QT500 hubs resist saltwater ambient; substantial section modulus absorbs crane-indexing shock events.
⚡ Power-Station Main Auxiliary
Main boiler-feed pump and condenser-cooling pump auxiliary drives on thermal-power-station and biomass-power-plant infrastructure. Long-cycle reliability across 30+ year design life of power infrastructure.
Why Choose Ever-power
Quality & Compliance
SL340 production runs under ISO 9001:2015 with full melt-traceability per cast-iron and cast-steel heat. Documentation pack covers RoHS, REACH, CE conformity, plus comprehensive FMEA documentation and 30-year fatigue-endurance analysis. For minerals-processing customers, supplementary shock-load profile compatibility documentation is available. For steel-plant customers, additional thermal-cycle endurance documentation supports high-temperature ambient deployment.
Customisation
Catalogue bore 150 mm; custom-bore variants from 140 mm to 160 mm produced under engineering review with 4-week lead time. QT500-7 ductile-iron hub is the standard; QT600-3 cast-steel variant is the engineering-preferred upgrade for primary mining-mill, steel-plant, and aggressive shock-load applications. Taper-bushed mounting via standard locking-assembly families is the only mounting option at this size.
Critical-Asset Aftermarket
SL340 slider plates and 40Cr alloy variants stocked for 2-business-day shipment. Mass per coupling 162 kg; sea-freight in heavy-duty reinforced crating with secondary shock-absorbing foam packaging. English-speaking engineering desk responds within 24 hours. For continuous-production critical-asset customers, pre-negotiated emergency-replacement protocols guarantee 5-working-day delivery.
Customer Reviews & Case Studies
★★★★★
Uruguay — Cement Plant Main Mill
Used in: Primary ball-mill main-drive coupling on a 1.2 Mt/y cement plant cement-grinding mill.
Feedback: “Specified the SL340 with QT600-3 cast-steel hubs and 40Cr alloy slider after detailed reliability-engineering review against gear-coupling alternatives. Seven years of three-shift continuous duty with one slider replacement during a major plant overhaul. The FMEA documentation supplied with the specification was material in our reliability-engineering qualification process. Excellent senior-engineered specification across the entire 7-year service window.”
★★★★★
Costa Rica — Integrated Pulp-and-Paper Mill
Used in: Pulp-stock primary refiner main-drive coupling on an integrated kraft pulp-and-paper mill.
Feedback: “Continuous-process duty with significant elevated-ambient and chemical-process exposure. The SL340 with QT500 hubs and synthetic-grease specification has handled 6 years of continuous duty with no unplanned events. Slider-wear inspection during the most recent planned shutdown indicated approximately 60 % service life consumed — clear margin against next major overhaul. Specification will be replicated across our planned plant expansion.”
★★★★☆
Panama — Container-Port Main Yard Cranes
Used in: Slewing-drive coupling on heavy ship-to-shore container cranes at a Pacific-coast container terminal.
Feedback: “Shock-load duty from container-indexing cycles plus salt-air ambient. The SL340 with QT500 hubs and IP54 sealed coupling guard has handled 5 years of three-shift duty with one slider replacement. Knock one star only because the heavy 162 kg coupling mass required pre-arranged hoist support during initial commissioning — added a half-shift to crane re-commissioning. Operational performance once installed has been excellent.”
Frequently Asked Questions
Why is keyway mounting no longer supported at the SL340 size?
At 20 000 N·m and above, the realistic shock-load profile of primary-process duty exceeds the keyway-shear endurance margin of a 150 mm parallel keyway under field-service conditions. Taper-bushed mounting via standard locking-assembly families eliminates this failure mode entirely. Engineering does not recommend keyway-only mounting at this rating regardless of the application class.
What is the QT600-3 cast-steel hub upgrade economics?
QT600-3 cast-steel hub variant carries approximately a 50 % cost premium over the standard QT500-7 ductile-iron specification, with a 4-week lead time premium beyond the standard 3-week SL340 delivery. For primary mining-mill, steel-plant, and routine 2× rated-torque shock-load duty, the QT600 upgrade typically pays back through extended slider-replacement intervals and reduced unplanned-failure probability within the first 3 years of service.
How is the SL340 handled during installation?
At 162 kg, the SL340 requires hoist or overhead-crane support during installation. Each hub masses ~75 kg, slider plate ~22 kg, and the assembled coupling 162 kg total. Pre-machined lifting-eyelet provisions on the hubs (M16 threaded holes on the outer face) are standard. Typical installation time is 90–120 minutes for a competent two-person crew with appropriate hoist support and pre-staged taper-bushed locking-assembly hardware.
Is hardfaced slider variant available?
Yes — for severe abrasive-environment installations (e.g., primary mining slurry pumps, severe-abrasive tailings handling), a hardfaced slider variant with localised tungsten-carbide deposit on the four wear faces is documented and available through engineering review. Lead time is approximately 8 weeks beyond the standard slider delivery; cost premium is approximately 3× standard slider.
What aftermarket support applies for primary-process customers?
For primary-process critical-asset customers, Ever-power offers comprehensive aftermarket support: pre-negotiated emergency-replacement protocols (5-working-day delivery from confirmed PO); buffer-stock programmes at customer-nominated 3PL warehouses; annual maintenance-review consultations; on-call engineering support during plant turnarounds; and 30-year part-availability commitment for slider plates and consumables. Programme terms are negotiated with the sales desk.
Quote SL340 for Primary-Process Heavy-Industrial Drives
For primary mining-mill main, cement-kiln main, steel-plant heavy auxiliary, and primary slurry-pump applications in the 210–260 kW slow-speed power class, the SL340 is Ever-power’s most senior-engineered specification for critical primary-process duty. Browse the wider SL series catalogue, read about Ever-power’s primary-process supply capability, or move directly to a B2B enquiry below.