Description
SL90 Industrial Cross-Slider Oldham Coupling — 90 mm Cast-Iron Hub Joint for Process Pumps and Conveyor Drives
The SL90 industrial Oldham coupling sits one step up from the entry-level SL70 in the heavy-industrial cross-slider family. With a 90 mm hub outside diameter, a 52 mm overall length, hub-bore options spanning 20 mm through 30 mm, and a 250 N·m continuous torque rating at 250 r/min, the SL90 is the natural fit for the small process pump, food-process auger, conveyor-head pulley, and feed-mill auxiliary drives that anchor light-industrial production. At this size the SL coupling becomes the default specification across an entire band of food, beverage, pulp-and-paper, and water-treatment OEM equipment — not because it is the cheapest option, but because its 20-year-plus service profile combined with its trivially simple maintenance routine makes it the lowest-total-cost option over equipment lifecycle.
The 250 N·m rating positions the SL90 specifically in the 1.5 kW to 5.5 kW continuous-power band. Within that band, the SL90 competes directly with elastomeric jaw couplings (cheaper to acquire, but with measurable backlash and elastomer fatigue), with grid couplings (longer service life, but requiring annual spring-pack inspection), and with flexible-disc couplings (precision parallel alignment required, complicating installation). The SL90’s combination of zero backlash, generous parallel-misalignment tolerance (0.7 mm), and 50 000-hour-class slider service life sits in a price-performance position that has kept it on OEM specifications across multiple equipment generations.
Specifications
| Parameter | Value |
|---|---|
| Model | SL90 |
| Nominal Torque (Tn) | 250 N·m |
| Permissible Speed (n) | 250 r/min |
| Bore Range (d) | 20 – 30 mm |
| Outside Diameter (D) | 90 mm |
| Hub Bore Diameter (D₁) | 45 mm |
| Overall Length (L) | 52 mm |
| Slider Plate Thickness (H) | 14 mm |
| Slider Clearance (S) | 0.5 mm |
| Moment of Inertia | 0.008 kg·m² |
| Mass | 2.6 kg |
| Radial Misalignment (Δy) | 0.7 mm |
| Angular Misalignment (Δα) | 0.5° |
| Axial Misalignment (Δx) | 1.4 mm |
| Shaft Engagement | Keyway + setscrew |
| Lubrication | Grease (re-pack annually) |
Materials
HT250 Cast-Iron Hubs
Sand-cast hubs from grey iron HT250 (GB 9439). At the SL90’s torque rating, the cast-iron section provides ample fatigue margin against the cyclic torsional loads of typical pump and conveyor service. Stress-relief annealing is performed prior to machining to prevent dimensional drift during the bore-and-keyway operations.
45-Steel Slider
The cross-slider is machined from medium-carbon 45-steel and surface-hardened to HRC 40–45 on the four sliding faces. For the 250 N·m duty class, this hardness specification delivers the wear life needed against the cast-iron hub slots under grease-lubricated industrial duty. 40Cr alloyed-steel slider is offered for high-cycle reversal applications.
Standard Keyway Mounting
Parallel keyway to GB/T 1096 (DIN 6885 / JIS B 1301), with bore tolerance H7 for precision sliding fit. M10 set-screw provides axial location. The keyway-mounting convention is universal across industrial plant maintenance and is supported by standard tooling at every machine shop globally.
Engineering Rationale for the SL90
For an integrator specifying a coupling between a 3 kW motor and a small process pump, the engineering question is rarely “which architecture offers the highest peak torque per millimetre of diameter”. It is, instead, “which architecture offers the most predictable 10-year ownership cost, the simplest installation, and the most field-serviceable wear parts”. The SL90 answers all three questions with the same straightforward design that has been in service for nearly a century: cast-iron hubs that outlast the host equipment, a slider plate that wears predictably and replaces in minutes, and a maintenance routine — annual grease repack — that is so simple it rarely gets skipped.
Compared to elastomeric jaw couplings, the SL90 eliminates the polymer spider that becomes the dominant failure mode after 3–5 years of service. Compared to grid couplings, the SL90 eliminates the spring-pack inspection that adds an annual maintenance touch point. Compared to flexible-disc couplings, the SL90 eliminates the precision laser-alignment requirement that adds time and skill to every install. The SL90 is, in many ways, the lowest-maintenance flexible-coupling architecture available at this torque class — which is exactly why it has remained on OEM specifications even as competing technologies have come and gone.
For broader selection guidance across the cross-slider family see our SL coupling selection resources.
Industry Applications
Dairy Process Pumps
Coupling between drive motor and centrifugal pump on milk-receiving, separator-feed, and CIP-circulation pump skids. Greased metallic interface meets dairy-plant maintenance familiarity.
Grain Mill Auxiliaries
Auger-conveyor and elevator-bucket drives on flour and feed mills. Cast-iron hubs absorb the shock loads of intermittent material loading without flexure fatigue.
Small Pulp & Paper
Stock-pump and stuff-box drives on small paper-recycling and tissue-converting lines. Misalignment tolerance forgives the cumulative misalignment of long shaft trains.
Sugar-Mill Auxiliaries
Cane-conveyor and bagasse-elevator drives on small-to-medium sugar mills. Long maintenance interval and slider field-replaceability suit seasonal mill operation.
Wastewater Treatment Pumps
Mid-sized centrifugal and progressive-cavity pump drives in municipal and industrial wastewater service. Greased interface tolerates the corrosive ambient of digester gas areas.
Salt & Mineral Processing
Crystalliser-rake and mineral-conveyor drives on solar-salt and small-mineral-processing operations. Dust-tolerant lubrication routine suits the local maintenance practice.
Why Choose Ever-power
Quality Documentation
SL90 production runs under ISO 9001:2015. Cast-iron raw material is sourced with documented melt traceability per heat. RoHS, REACH, and CE conformity documentation supplied as standard. For dairy and food customers, plant-suitability declarations covering food-contact distance and grease compatibility are available on request.
Customisation
Catalogue bore range 20–30 mm; oversized bores up to 35 mm produced on request. Imperial bores (3/4″, 7/8″, 1″, 1-1/8″) available for North American export markets. Ductile-iron QT500-7 hub upgrade is documented for chloride-rich and seawater-spray environments. Logo-cast hubs are an established OEM private-label option for resale.
Aftermarket
SL90 spare slider plates and replacement key sets stocked under part numbers SL90-SLIDER and SL90-KEY. 2-business-day shipping standard. English-speaking engineering desk responds within 24 hours on installation, troubleshooting, and de-rating queries.
Customer Reviews & Case Studies
★★★★★
United Arab Emirates — Solar-Salt Operation
Used in: Crystalliser-rake drives on a 200-hectare solar-salt operation.
Feedback: “Ambient salt exposure has been catastrophic for every other coupling architecture we tried — including supposed marine-grade jaw couplings that failed within 18 months. The QT500 ductile-iron hub variant has now passed 5 years of service with no measurable corrosion and only the scheduled annual grease repack. Lowest-maintenance coupling on this site by a clear margin.”
★★★★★
Kazakhstan — Sunflower-Seed Processing
Used in: Seed-elevator drive on a medium-scale sunflower processing plant.
Feedback: “Equipment runs continuous 24/6 during harvest season, then sits idle for several months. The SL90 has performed reliably across this duty cycle for 7 years. Slider plate has been replaced twice during that period — both times during planned shutdowns, with zero unplanned downtime attributable to the coupling.”
★★★★☆
Egypt — Wastewater Treatment Authority
Used in: Effluent-pump drive on a municipal wastewater plant outside Cairo.
Feedback: “Sewer-gas ambient is challenging for every coupling architecture. The SL90 holds up well with bi-annual grease repacks. Knock one star only because we wish the catalogue listed a hot-dip-galvanised hub option for our worst sour-gas zones — engineering supplied this as a custom finish, but at a 5-week lead time addition.”
Frequently Asked Questions
How frequently should the SL90 slider be inspected?
For typical industrial duty, a visual inspection at every annual grease-repack interval is sufficient. Look for evidence of bright-metal wear on the slider faces — a small amount of polishing is normal and indicates correct operation; visible step-wear of more than 0.5 mm depth is an indicator that slider replacement should be scheduled at the next planned shutdown.
Can the SL90 absorb hydraulic-pump pulsations?
The slider geometry provides a small amount of torsional damping under pulsation, which helps reduce vibration transmission from positive-displacement pumps. For dedicated pulsation-suppression applications, however, a dedicated elastic coupling is more appropriate than the SL90. We can recommend an appropriate alternative on enquiry.
What is the maximum continuous power the SL90 can transmit?
At 250 r/min and 250 N·m, the SL90 transmits 6.5 kW continuously. Power capacity scales linearly with operating speed: at 100 r/min the continuous rating is 2.6 kW, and at 50 r/min it is 1.3 kW. For sustained operation requiring higher power, the SL100 is the next step in the family.
Can the SL90 be installed in a wash-down environment?
Yes — for direct wash-down service we recommend the QT500 ductile-iron hub variant for corrosion resistance, plus a calcium-sulfonate grease specification that resists wash-out under pressure-wash exposure. With these specifications the SL90 has been validated in dairy and beverage plant wash-down service for over a decade.
Is OEM private-label production available at small volumes?
Yes — minimum order quantity for cast-logo private-label production is 100 pieces per pattern. Set-up cost is amortised across the first production lot. For smaller volumes, post-machining laser-etched OEM labels are available with no setup cost and MOQ of 25 pieces.
Specify the SL90 for Light-Industrial Drives
For dairy, food-process, grain-mill, and small wastewater OEM equipment, the SL90 has been the default flexible-coupling specification for generations. Browse the wider SL series catalogue, read about Ever-power’s cast-iron manufacturing capability, or proceed to a B2B enquiry below.