VSI250855-N Slewing Bearings

VSI250855-N Slewing Bearings — INA VSI Standard 25 Internal Gear Four-Point Contact Ball Slewing Ring

VSI250855-N Slewing Bearings are a single-row, four-point contact ball slewing ring with an 855 mm raceway diameter, 137 kg weight, and a static axial load capacity of 3,050 kN. Designed as a direct OEM-compatible replacement for the INA VSI Standard 25 series, this bearing carries axial, radial, and tilting moment loads through one compact ring. Luoyang Heng Guan Bearing Technology Co., Ltd. manufactures and supplies this model with precision grades P0, P6, and P5 available to order.

What Is the VSI250855-N?

The VSI250855-N Slewing Bearings belongs to INA's VSI Standard 25 heavy-duty slewing ring family. A single row of GCr15 balls handles axial loads, radial loads, and tilting moment loads simultaneously, which reduces assembly height compared to two-row designs while maintaining the C0a 3,050 kN static axial capacity.

The "N" suffix indicates a normalized internal gear profile — the pinion meshes inside the ring bore, keeping the drive assembly compact and well-shielded from external debris. The gear specification is module m10 with 73 teeth and a pitch circle of 730 mm, the heaviest gear module in the INA four-point contact ball family. Permissible tooth force is 68 kN at tooth-root fatigue strength (shock factor 1.2), with a 98.9 kN fracture limit at shock factor 1.35.

This series shares mounting compatibility across the full VSI Standard 25 family in the 755–1055 mm raceway range, so replacement or upgrading does not require redesigning the existing bolt pattern.

Full Technical Specifications

Source: Schaeffler medias official catalogue (retrieved 2026-08-17)

Key Design Features

Four-point contact ball structure — one ball row handles axial, radial, and tilting moment loads at once, reducing assembly height while maintaining the C0a 3,050 kN static axial capacity.

Internal gear, m10/z73 — the gear teeth are normalized (N) on the bearing ring, allowing an inside swing pinion to engage directly. Permissible tooth force is 68 kN at tooth-root fatigue strength (shock factor 1.2), the value to be used for continuous digging duty; 98.9 kN is the tooth-root fracture limit at shock factor 1.35 and must not be applied as a working load.

50Mn / 42CrMo4 ring steel — raceways are induction-hardened to 55–62 HRC surface hardness. The core remains ductile to absorb sudden overloads without brittle fracture.

Double-lip NBR seals — retain grease and block contaminants across the full -25 to +80 °C operating range. Anti-corrosion treatment options are available for offshore or high-humidity environments.

Section height 80 mm — the VSI Standard 25 heavy section offers roughly 2× the static axial capacity and tooth force rating of the VSI Standard 20 series (56 mm section, m5–m8 gear), within a comparable outside diameter envelope.

Precision options P0, P6, and P5 — normal radial clearance is 0.03–0.13 mm, suitable for applications requiring clearance-controlled rotation.

Typical Applications

The 855 mm raceway and m10/z73 internal gear suit a range of heavy-duty rotating assemblies:

· Heavy excavators (40–60 tonne class) — swing system connecting the upper carriage to the undercarriage, where the four-point contact ball design handles sudden digging shock and tilting moments.

· Tower cranes and mobile cranes — slewing sections where the inside pinion drive keeps the drive train compact within the crane mast or boom structure.

· Wind turbine yaw systems — internal-gear rings driven by a central pinion for nacelle rotation across the full -25 to +80 °C temperature range.

· Mining shovels and heavy conveyors — sealed four-point design resists dust ingress and shock in aggregate processing environments.

· Radar and antenna platforms — internal-gear rings with central pinion drive for stable, low-clearance tracking rotation.

· Heavy rotary indexing tables — process equipment turntables where keeping the drive inside the table footprint is a layout requirement.

· Offshore and marine deck cranes — NBR-sealed design with anti-corrosion treatment options for salt-spray environments.

Manufacturing and Quality

Heng Guan's production facility in Luoyang operates CNC vertical lathes, CNC quenching machines, CNC gear shapers, machining centers, grinding machines, and large gear hobbing machines. Finished product inspection uses coordinate measuring machines, vibration testers, and life testing machines. Products are manufactured to DIN, ISO, and GB standards.

Precision grades P0, P6, and P5 are all available. Custom non-standard variants — including modified bore dimensions, alternative gear profiles, or different seal materials — can be quoted based on customer drawings. OEM and ODM partnerships are supported.

FAQ

Q: What is the difference between VSI Standard 25 and VSI Standard 20 series?

A: The Standard 25 is the heavier system: 80 mm section height versus 56 mm, module-10 gear versus m5–m8, M20 fixing threads versus M12, and roughly 2× the static axial and tooth force capacity at a similar outside diameter.

Q: What is the difference between VSI250855-N and VSI250755-N?

A: Both share the same 80 mm section height. The VSI250855-N has an 855 mm raceway (710 × 955 × 80 mm, 137 kg, m10/z73, C0a 3,050 kN). The VSI250755-N has a 755 mm raceway (610 × 855 × 80 mm, 119 kg, m10/z63, C0a 2,700 kN).

Q: How is an internal-gear slewing ring driven?

A: A pinion meshes with the gear teeth inside the ring bore. This arrangement shields the mesh from external debris and reduces the radial footprint compared to external-gear designs.

Q: What is the recommended re-lubrication interval?

A: For heavy equipment such as excavators, every 100 operating hours is a standard interval for the raceway. For open gearing, every 50 hours is recommended. In high-humidity or continuous-rotation applications, automatic lubrication systems help purge old grease and contaminants.

Q: What bolt grade is required for mounting?

A: High-strength bolts of grade 10.9 or 12.9 (ISO) are required. The unthreaded shank must sit in the shear plane. Outer bolt circle: 28 holes on 915 mm PCD; inner bolt circle: 28 × M20 threaded holes on 794 mm PCD.

Q: Can I order a single unit of the products?

A: Yes. Single-unit orders are accepted. Contact mia@hgb-bearing.com for pricing and availability.

Contact Us

For pricing, lead time, and technical enquiries about VSI250855-N Slewing Bearings, reach our engineering team directly at mia@hgb-bearing.com.