The BB20025 metric thin section ball bearing (open four-point Type X, 200 × 260 × 25 mm) from the BB series matches common crossed roller envelopes while running at lower friction torque. Dynamic radial 50.22 kN, moment 4333 N·m, clearance 0.060–0.090 mm. Order as LYDL-20025. Compare related sizes and request a drawing or quote from LYDL.
A 260 mm bearing is as much a logistics and metrology problem as a tribology one. The BB20025 carries the BB metric range into that territory: a 200 mm bore in a 30 × 25 mm cross section, 50.22 kN of dynamic radial capacity and a 4,333 N·m moment rating — in a ring that weighs 3.40 kg.
This page is written for the engineers who have to lift it, house it and sign off its runout: dimensions and ratings first, then the two problems that decide large thin-section projects — housing stiffness and handling — before applications and acceptance inspection.
| Parameter | Symbol | Millimeters | Inches |
|---|---|---|---|
| Bore diameter | d | 200 | 7.874 |
| Outside diameter | D | 260 | 10.236 |
| Width | B | 25 | 0.984 |
| Cross section (radial × width) | – | 30 × 25 | 1.181 × 0.984 |
| Max. fillet radius | r | 2.5 | 0.098 |
Bore 200 mm, outside diameter 260 mm, width 25 mm, with a 2.5 mm maximum shoulder fillet — the largest fillet in the five BB sizes covered here, sized for the heavier shafts a 200 mm bore implies. Inch equivalents are tabulated for legacy imperial drawings.
| Parameter | Symbol | Value | Notes |
|---|---|---|---|
| Dynamic radial load rating | Cr | 50.22 kN (5,121 kgf) | LYDL spec = SKF Kaydon catalog |
| Dynamic axial load rating | Ca | 76.70 kN (7,820 kg) | LYDL specification |
| Dynamic moment rating | M | 4,333 N·m | LYDL spec = SKF Kaydon catalog |
| Standard diametral clearance | – | 0.060–0.090 mm | standard band at this size |
| Inner / outer ring runout (max) | – | 0.030 mm | radial runout |
| Approximate mass | m | 3.40 kg | open execution |
The 50.22 kN (5,121 kgf) dynamic radial rating, 76.70 kN axial rating and 4,333 N·m moment rating for this size are cross-referenced between the LYDL specification table and the SKF Kaydon BB metric catalog (designation KDN.39336001). Static ratings are quoted on request; at this diameter and for slow, heavily loaded stages, the static figure frequently governs the selection.
The ring follows the housing — that is the design rule for every thin section, and at 260 mm it becomes the project risk. A 30 × 25 mm section will conform to its seat, so a housing that distorts under bolt load or applied moment passes that distortion straight into the raceway. Machined housings are strongly preferred over fabricated ones at this diameter; bolt patterns should be symmetric about the load path; and the housing bore should be verified round after final tightening, not just at machining. LYDL reviews housing drawings for BB large sizes on request — the review is cheaper than chasing a 0.030 mm runout that was never the bearing’s fault.
| Source | Designation | Notes |
|---|---|---|
| LYDL | LYDL-20025 | internal reference for this size |
| SKF / Kaydon | BB20025 (KDN.39336001) | BB metric thin section series |
| Envelope match | 200 × 260 × 25 mm | matches common RB-style crossed roller boundaries |
LYDL-20025 is the internal reference; BB20025 with the SKF designation KDN.39336001 identifies the same envelope and ratings in the Kaydon BB metric catalog chain.
At 3.40 kg the ring is one-hand-liftable — and still needs more care than a smaller size, because a thin section at 260 mm distorts under point loads that a smaller ring would shrug off. Support the ring on its full face, never on the bore edge; lift with webbing rather than hooks or points; keep it horizontal in transport; and open the packaging only at the installation point. The inspection and packaging routine shown here is standard for every large-size shipment.
Medical imaging equipment, where auxiliary rotation axes — detector and collimator supports, scanner peripheral stages — put a premium on runout, mass and a clear central bore. Radar and antenna pedestals, where slow, precise slewing under wind-induced moment is the duty cycle. Heavy camera turrets and robotic positioners, and large-diameter encoder mounts for telescope and industrial vision axes. The common requirement is a big central clearance — for optics, cable wrap or the payload itself — carried by a bearing light enough not to dominate the structure.
| Reference model | Bore d (mm) | Outside D (mm) | Width B (mm) | Dynamic radial |
|---|---|---|---|---|
| BB15025 | 150 | 210 | 25 | 43.82 kN |
| BB20030 | 200 | 280 | 30 | 71.47 kN |
| BB25025 | 250 | 310 | 25 | 56.07 kN |
The same 25 mm width continues at 250 mm bore (BB25025), while the wider BB20030 at 30 mm width carries 71.47 kN — the moment-capacity upgrade path at constant bore. The full large-size grid from BB15025 upward is tabulated on the BB series overview page; the BB10020 marks where the mid-range ends.
Radial runout on both rings is verified to a 0.030 mm maximum before shipment — a figure that is deliberately honest about what a 260 mm open ring holds in this class; whether it meets your axis requirement is a machine-level evaluation. On arrival, repeat the measurement with your own equipment on a clean, temperature-stable surface and record it as the baseline; large rings respond to temperature enough to matter at this tolerance level. The standard diametral clearance band of 0.060–0.090 mm is part of the same honesty: at 200 mm bore, tighter bands are possible but are quoted per application rather than promised as standard.
Support it on its full face — never on the bore edge or a single point — lift with webbing rather than hooks, keep it horizontal in transport, and open the packaging only at the installation point. A thin section at this diameter distorts under point loads that a smaller ring would ignore.
Stiff enough to stay round under the mounting bolts and the applied moment, because the ring follows the housing. Machined rather than fabricated housings, symmetric bolt patterns and a post-tightening roundness check are the practical rules; LYDL reviews housing drawings for large BB sizes on request.
Four-point contact carries moment inside the single row, and 4,333 N·m is the catalog dynamic moment rating — whether a continuous cantilever duty is acceptable must be assessed from the combined loads, speed, life target and support conditions. LYDL engineering runs that assessment from your load geometry before the order is placed.
0.030 mm maximum radial runout on both rings is the standard factory figure at this size, measured before shipment; records are available on request. Tighter classes are quoted case by case — at this diameter metrology and lead time both move with the class.
The 200 mm class is typically made to order rather than stocked; lead time, MOQ and current stock status are confirmed per size at quotation. Engage LYDL early in the design cycle.
Ask for the current lead time, MOQ and stock status when you request a quotation, or use the LYDL contact page. The drawing package — full dimension sheet, runout data and mounting guidance — is available before ordering so the housing design can freeze in parallel with production.
Values cross-check against the SKF Kaydon BB series catalog and LYDL’s manufacturing specification. For adjacent large-diameter precision technologies see the Schaeffler PRG catalog; the BB series overview and thin section category place this size in the family. All figures are reference inputs for sizing, not application approvals.
