RKS.21.1091 Slewing Bearings
• BDI USA / Motion Industries (mrosupply) — Top US distributors list this model: BDI describes "984MM Bore; 1198MM Outside Diameter; 56MM Width; Special Axial Seal" — proves the US/EU procurement link, and "listed in US distributor networks" is the strongest purchase-risk reductant for large-size segments.
- Product Description
RKS.21.1091 Slewing Bearings — Light Series External Gear Four-Point Contact Turntable Bearing for Heavy-Load Rotary Applications
Luoyang Heng Guan Bearing Technology Co., Ltd. is a modern enterprise specializing in high-precision bearing R&D, manufacturing, and sales. Located in Luoyang — China's bearing industry hub — our 50+ member team brings over 30 years of expertise. The RKS.21.1091 Slewing Bearings is the largest model in the SKF RKS.21 light series: 984 mm bore × 1198 mm OD × 56 mm height, 86 kg, with the highest static load rating in its family at C0 = 766 kN. ISO9001 certified, RoHS compliant, exported to 50+ countries. Diameter range: 50–10,000 mm; precision grades P0/P6/P5/P4 available.
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What Makes the RKS.21 1091 Stand Out?
This is the flagship model of the RKS.21 light series — and it shows in the numbers. You get a C0 static axial load rating of 766 kN, which is the highest in the entire RKS.21 family — 2.7× greater than the smallest model in the series.
The external gear runs module 8 with 148 teeth — the largest tooth count in the m8 group. Combined with a four-point contact ball design using 20 mm balls, it handles combined axial, radial, and moment loads efficiently in a compact, lightweight package.
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Full Technical Specifications
| Parameter | Value |
|---|---|
| Mean raceway diameter dm | 1091 mm |
| Outside diameter D (incl. gear tip) | 1198 mm |
| Inner diameter d | 984 mm (38.74 in) |
| Outer-ring centring diameter D2 | 1092.5 mm |
| Inner-ring centring diameter d1 | 1048 mm |
| Inner-ring inner diameter d2 | 1089.5 mm |
| Total height H | 56 mm ±1 mm (2.20 in) |
| Weight | 86 kg |
| Outer-ring bolt pattern | 22 × M12 on Je = 1135 mm circle |
| Inner-ring bolt pattern | 20 × Ø18 mm on Ji = 1012 mm circle |
| Gear pitch circle d0 | 1184 mm |
| Gear module × teeth | m8 × z148 (pressure angle 20°) |
| Permissible gear tooth force Tf | 21 kN normal / 72 kN max |
| Basic dynamic axial load rating C | 244 kN |
| Basic static axial load rating C0 | 766 kN (Light series highest) |
| Ball diameter | 20 mm (four-point contact) |
| Ring material | C45E / 42CrMo4 / 50Mn |
| Raceway hardness | HRC 55–62 (induction hardened) |
| Seal | NBR integral double-sealed / Special Axial Seal |
| Operating temperature | −40 ~ +110 °C |
| Lubrication | NLGI 2 lithium EP grease, 4 × AM8×1 fittings |
| Speed limit | 1.5 m/s continuous / 2.0 m/s short-time |
| Running accuracy | Radial ≤ 0.2 mm / Axial ≤ 0.3 mm |
> Dimension note: 1048 mm is the inner-ring centring diameter — not the width dimension. The correct catalogue specification is 984 × 1198 × 56 mm / 86 kg. Some market listings show 1198.1 mm OD or 84 kg — the catalogue values above are correct.
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Key Application Areas
This four-point contact ball slew ring is built for demanding, low-speed, high-load rotation. Here's where it performs best:
Excavators & Construction Machinery — The external gear and high C0 rating make it a proven choice for excavator swing bearings and mobile crane turntable bearings. It handles shock loads and debris ingress in tough site conditions.
Crane & Lifting Equipment — Large lifting platforms and crane turntable bearings benefit from the 766 kN static capacity and durable induction-hardened raceways.
Filling & Packaging Lines — The low-noise, double-sealed design suits high-speed rotary filling machines where cleanliness and smooth rotation matter.
Metallurgical Equipment — Blast furnace gas covers and similar heavy industrial rotary systems rely on the bearing's high load tolerance and wide temperature range.
Large OEM Rotary Mechanisms — Whether it's a custom slewing platform or a specialized machine, this light series slewing bearing supports OEM integration with flexible bolt patterns.
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Interchange & Cross-Reference Guide
If you're sourcing a replacement or equivalent, here's what you need to know:
- INA VLA201091-N / VLA201091 — inferred interchange in the same size family; verify bolt circle before installation
- Schaeffler 88.1144.00 — corresponding reference by series pattern
- RKS.061.20.1094 — similar outside diameter (1198.4 mm) but different bore (1022 mm vs. 984 mm); not a direct drop-in replacement — always confirm d1 and bolt circle before substituting
For US/EU engineers: 984 mm = 38.74 in, 1198 mm = 47.17 in, 56 mm = 2.20 in.
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Why Choose Heng Guan Bearing?
You're not just buying a bearing — you're choosing a manufacturing partner with depth.
Precision Manufacturing: Our facility runs CNC vertical lathes, CNC gear shapers, large gear hobbing machines, and grinding machines. Every bearing goes through coordinate measuring machines and vibration testers before it leaves the factory.
Verified Dimensions You Can Trust: We publish catalogue-correct specs — 1198 × 984 × 56 mm, 86 kg — so your engineering team doesn't have to second-guess misprint listings found elsewhere online.
Global Reach: Our products are shipped to 50+ countries including the USA, Germany, UK, Italy, Australia, and across the Middle East. We comply with DIN, ISO, and GB standards.
Flexible Service: OEM/ODM support, installation guidance, old product mapping, and non-standard customization are all available. MOQ starts at 1 pc.
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Frequently Asked Questions
What is RKS.21.1091?
It is the largest model in the SKF RKS.21 light series — a single-row, four-point contact ball slewing ring bearing with an external gear. Key specs: 984 mm bore, 1198 mm OD, 56 mm height, 86 kg, C0 = 766 kN.
What are the exact dimensions of RKS.21 1091?
Bore 984 mm (38.74 in), OD 1198 mm (47.17 in) including gear tips, height 56 mm (2.20 in). Gear pitch circle 1184 mm, module 8, 148 teeth. Note: 1048 mm is the inner-ring centring diameter, not the bearing width.
Is RKS.21.1091 equivalent to INA VLA201091-N?
INA VLA201091-N and Schaeffler 88.1144.00 are the corresponding interchange references. We recommend verifying bolt circle and centring diameter details before replacement. The medium-series RKS.061.20.1094 shares a similar OD but has a different bore (1022 mm) and is not a direct interchange.
What is the load capacity?
Dynamic axial load rating C = 244 kN; static axial load rating C0 = 766 kN — the highest in the RKS.21 family. Permissible gear tooth forces: 21 kN (normal) and 72 kN (maximum).
Is this bearing available in stock?
Stock models typically ship within 3–7 business days. Non-stock standard models are available in 25–30 days. Contact Us to confirm current availability and lead time.
What seal type does it use?
It uses an NBR integral double-sealed design, also referred to as a Special Axial Seal. Operating temperature range is −40 to +110 °C — suitable for both cold-climate and high-heat environments.
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Packaging & Shipping
Each bearing is packed in standard export-grade packaging — anti-rust film wrap, wooden crate, and moisture-absorbing desiccant. Custom labeling is available for OEM orders. We support sea freight, air freight, and express delivery to 50+ countries worldwide.
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Get a Quote for RKS.21.1091 Slewing Bearings Today
Ready to source factory-direct? Email us at mia@hgb-bearing.com — MOQ 1 pc, fast response guaranteed.
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