Description
WH8 Light-Industrial Cast-Iron Oldham Coupling — Heavy Reduction-Output and Mill-Feed Drives
The WH8 cast-iron Oldham coupling enters the heavy upper tier of the WH family. With 1 800 N·m rated torque, 50–70 mm bore range, 55 kg mass, and 2 400 rpm permissible speed, the WH8 is the coupling of choice for heavy gear-reducer output couplings, large agricultural machinery principal drives (large silage-harvester main drives, large bale-press primary outputs), heavy light-industrial mill-feed systems, and the higher-end small-plant crushing and screening auxiliary drives. At 55 kg, the WH8 requires hoist or two-person-plus-equipment handling, and the engineering specification at this mass class typically involves formal installation planning rather than field improvisation.
The WH8 occupies an interesting comparative position in the Ever-power catalogue. At 1 800 N·m torque, it overlaps with the entry-level SL series (SL70: 125 N·m — significantly lower; SL90: 250 N·m — still much lower) only in bore size, not in torque. The WH8’s torque at 2 400 rpm actually places it in the domain of industrial equipment that would conventionally be considered mid-weight rather than light-industrial — demonstrating how the WH family’s high-speed envelope enables relatively small and economical cast-iron couplings to transmit substantial mechanical power. The coupling’s 30–40 % mass advantage over SL-series members at comparable bore ranges makes the WH8 the preferred specification wherever 2 400 rpm operation is feasible and the additional torque reserve of the SL family is unnecessary.
Specifications
| Parameter | Value |
|---|---|
| Model | WH8 |
| Nominal Torque (Tn) | 1 800 N·m |
| Permissible Speed (n) | 2 400 rpm |
| Bore Range (d) | 50 – 70 mm |
| Mass | 55 kg |
| Radial Misalignment (Δy) | 1.0 mm |
| Angular Misalignment (Δα) | 0.5° |
| Axial Misalignment (Δx) | 1.0 mm |
| Hub Material | HT250 grey cast iron |
| Slider Material | Induction-hardened steel |
| Lubrication | Grease (6-monthly) |
| Shaft Engagement | Keyway + setscrew (M14) |
Materials
HT250 Cast-Iron Hubs (Standard WH8+)
HT250 grey cast iron with stress-relief annealing is the standard hub specification for WH8 and above. The higher tensile strength relative to HT200 (used in WH1–WH6) provides adequate section-modulus for the 1 800 N·m torque rating across the 50–70 mm bore range, with a documented 2× safety factor against peak-torque events. Each hub masses approximately 26 kg; hoist or two-person-with-support installation is required at this mass class.
Heavy Induction-Hardened Slider
Induction-hardened carbon steel cross-slider. At 55 kg coupling mass the slider component is approximately 5–6 kg — a manageable individual field-replacement item. The hardened-steel-on-HT250-cast-iron interface provides predictable linear wear characteristic, enabling accurate inspection-based service-life planning at annual or semi-annual maintenance intervals.
M14 Setscrew + Keyway (6-monthly grease)
H7-reamed bore with parallel keyway to GB/T 1096, M14 set-screw for axial location. At the WH8’s torque and bore class, grease-repack interval shortens from annual (WH1–WH7) to 6-monthly — the larger slider interface area requires more frequent lubrication replenishment to maintain optimum film thickness during the higher-power sliding-friction events. M14 Loctite 243 is recommended for shock-load applications.
The WH Family at Heavy Duty
The WH8 and above demonstrate that the WH family’s cast-iron architecture can deliver meaningful heavy-duty performance at substantially lower mass and cost than competing SL-family or industrial gear-coupling specifications, provided the application operating speed is compatible with the WH family’s rpm envelope. At 2 400 rpm and 1 800 N·m, the WH8 transmits approximately 452 kW of instantaneous power — an impressive figure for a 55 kg cast-iron coupling. The SL family members capable of similar torque (SL280: 10 000 N·m, SL260: 9 000 N·m) operate at far lower speeds and are substantially heavier.
For OEM equipment designers specifying gear-reducer output couplings, the WH8 fits a natural engineering niche: the gear-reducer output shaft is typically the highest-torque, lowest-speed shaft in the drive train, but at the WH8’s power class, the reducer output speed is still in the 1 000–2 000 rpm range — well within the WH8’s 2 400 rpm envelope. Specifying a WH8 at the reducer output rather than an SL family member saves 40–60 % of coupling mass and typically 30–40 % of acquisition cost, with no compromise in torque-transmission reliability. For system integrators and OEM designers, this mass-and-cost saving across a population of drive trains is a meaningful BOM optimisation. See the full Ever-power coupling guide for cross-family selection comparisons.
Industry Applications
⚙️ Heavy Gear-Reducer Outputs
Output-shaft to driven-machine coupling on heavy-duty gear-reducer installations in general industry, food-processing, and chemical-plant equipment. WH8 mass advantage over SL-family alternatives is most pronounced here.
Large Agricultural Machinery
Main-drive coupling on large silage-harvesters, large round-bale-press primary outputs, and large feed-wagons. High-speed WH8 envelope compatible with agricultural PTO-coupled machinery speed ranges.
Heavy Mill-Feed Systems
Feed-screw and apron-feeder principal drives on light industrial milling operations. Near-zero-backlash supports consistent feed-rate control for product-quality management.
⛏️ Small Screening-Plant Main
Principal drives on small aggregate-screening plants and light minerals-processing operations. Shock-load tolerance absorbs material-impact events at screen-deck loading points.
Heavy Industrial Pumps
Main-drive coupling on large centrifugal and gear-pump installations in the 15–22 kW motor class for industrial, municipal, and process-plant applications.
Legacy Heavy Retrofit
Drop-in replacement for legacy gear-reducer, large-compressor, and heavy-industrial coupling specifications where the original has underperformed or become commercially unavailable.
Why Choose Ever-power
Quality & Compliance
WH8 production under ISO 9001:2015. Documentation covers RoHS, REACH, CE. HT250 material certification standard. The 6-monthly grease-repack schedule documentation supports maintenance-plan integration for heavy equipment operators.
Mass-and-Cost Advantage
30–40 % mass and 30–40 % cost advantage versus SL-family alternatives at comparable bore ranges, provided the 2 400 rpm speed constraint is acceptable. Hub-only and slider-only supply options support retrofit economies.
Aftermarket
WH8 sliders and hubs stocked for 2-business-day shipment. 55 kg requires freight shipping. Engineering responds within 24 hours. Distributor-programme pricing supported.
Customer Reviews & Case Studies
★★★★★
DR Congo — Mining-Infrastructure Operator
Used in: Heavy gear-reducer output coupling on a mineral-concentrator feed-screw installation.
Feedback: “Specified WH8 instead of SL-family alternative primarily on mass advantage — site hoist capacity constrained to 60 kg for this installation position. WH8’s 55 kg was the critical enabler. Four years of three-shift operation without coupling-related downtime. The 6-monthly grease schedule has integrated cleanly into our site maintenance calendar. Excellent cost-optimised specification for our constraints.”
★★★★★
Angola — Cement-Plant Feeder
Used in: Apron-feeder principal drive coupling on a regional cement-production plant.
Feedback: “Cement-dust ambient with continuous 24/7 operation. WH8 in sealed coupling guard has performed without coupling-related incident for 5 years, with semi-annual grease repack at the only scheduled maintenance touchpoint. The combination of HT250 cast-iron hubs and hardened steel slider has proven durable in the cement-dust environment.”
★★★★☆
Mozambique — Agricultural Mechanisation Programme
Used in: Main-drive coupling on large silage-harvester principal output shafts for a commercial sorghum-silage programme.
Feedback: “High-throughput seasonal duty with aggressive organic-material ambient. WH8 has handled 4 harvesting seasons without coupling failure. Knock one star only because replacement slider stock for remote rural deployment was logistically challenging — we had to pre-position spares ahead of each season. Would benefit from regional distributor stocking. Otherwise outstanding seasonal-duty specification.”
Frequently Asked Questions
Why does grease-repack interval shorten to 6-monthly at WH8?
At 55 kg coupling mass and 1 800 N·m torque, the slider interface area is substantially larger than smaller WH members. The grease film across this larger area degrades more quickly under the sustained sliding-friction work of heavy-duty operation. The 6-monthly repack interval maintains adequate film thickness across the full service window; extending beyond 6 months at WH8 and above risks progressive film-starvation leading to accelerated slider wear.
What is the WH8’s advantage over SL-family alternatives at this bore range?
At 50–70 mm bore, SL family members with comparable bore range (SL series from SL170 upward) have much higher torque ratings (typically 2 000+ N·m) but operate only at 250 rpm or below. For applications requiring 1 000–2 400 rpm, the WH8’s higher-speed envelope at 1 800 N·m is the more appropriate specification — 55 kg vs. typically 90+ kg for comparable SL members, and substantially lower acquisition cost. For applications below 500 rpm requiring above 1 800 N·m, the SL family is the correct choice.
Can the WH8 be used in dusty industrial environments?
Yes, with appropriate dust exclusion through a sealed coupling guard. For cement-dust, grain-dust, and mineral-dust environments, specify an IP55-rated coupling guard and shorten grease-repack to quarterly (every 3 months) to flush any ingested particulate from the slider interface. The HT250 cast-iron hub surface develops a natural protective oxide layer that resists mild chemical and abrasive ambient well.
What M14 setscrew torque is recommended?
The standard M14 setscrew should be torqued to 55 N·m for class 10.9 hardware (standard supply). For shock-load applications (crushers, compactors, heavy agricultural equipment with foreign-object inclusion risk), apply Loctite 243 medium-strength thread-lock to the setscrew before final tightening to prevent vibration-induced backing-out. Re-check setscrew torque after the first 50 operating hours following initial installation or slider replacement.
What aftermarket logistics support is available for remote site operators?
For remote-site operators (mining sites, large agricultural operations, offshore platforms), Ever-power recommends pre-positioning seasonal buffer stock — typically 2 slider plates and 1 complete coupling per installed WH8 — at a local logistics hub ahead of planned intensive-use seasons. Ever-power supports pre-season purchase orders with firm delivery commitments, supporting operators to build their site safety-stock ahead of peak-demand periods. Sales desk coordinates appropriate logistics routes for remote delivery on request.
Quote WH8 for Heavy Gear-Reducer and Mill-Feed Applications
For heavy gear-reducer output, large agricultural machinery, heavy mill-feed, small screening-plant, and heavy industrial-pump applications in the 1 800 N·m mid-speed class, the WH8 offers a compelling mass-and-cost advantage over heavier SL-family alternatives. Browse the wider WH series catalogue, read about Ever-power’s industrial coupling supply, or enquire below.