VSA250855-N Slewing Bearings

VSA250855-N Slewing Bearings | INA VSA25 Series External Gear Four-Point Contact Slewing Ring

VSA250855-N Slewing Bearings belong to the INA VSA25 heavy series — a single-row four-point contact ball slewing ring with an 855 mm raceway diameter, 997 mm outside diameter, and 80 mm section height. The ring weighs 145 kg and carries a static axial load (C0a) of 3,050 kN. Its external gear (module 9, 109 teeth) allows a pinion to mesh from outside the ring, making it a common choice for heavy excavators, cranes, and large rotating excavator.

Why the VSA250855-N Is Suited for Heavy-Duty Applications?

The VSA250855-N Slewing Bearings belongs to the VSA25 heavy series, which uses an 80 mm section height — larger than the 56 mm section of the VSA20 series. This additional section depth supports a static axial load (C0a) of 3,050 kN, which is approximately twice the capacity of a comparable series-20 ring at a similar outside diameter.

Many designs eliminate thrust bearings by using a single row of GCr15 balls to manage axial, radial, and tilting moment loads due to the four-point contact ball design. Normalised (N) teeth profile on module 9, 109 teeth, 981 mm pitch circular external gear. A pinion meshes outside the ring, making the drive system on big excavators and tower cranes field-accessible for inspection and repair.

With induction-hardened raceways (55–62 HRC surface hardness), 50Mn or 42CrMo4 alloy steel rings have ductile cores that can bear intermittent shock loads. NBR double-lip seals keep dust and moisture out of the raceway. Operating temperatures are -25 to +80 °C.

Full Technical Specifications

Key Application Areas

Heavy Excavators & Cranes — Excavators in the 40–60 tonne class typically pair an external-gear slewing ring with an outside swing pinion. The m9 gear and C0a 3,050 kN rating are suited to absorb the digging shock loads that can overstress a lighter series-20 ring. Tower cranes and mobile cranes use the same external-gear configuration for the slewing section.

Solar Trackers & Slewing Drives — Large utility-scale solar trackers mount a worm drive that meshes with the external gear from outside the ring. The series-25 section height supports the elevated tilt moments generated by large panel arrays.

Wind Turbine Yaw Systems — Yaw bearings use external-gear rings with drive pinions mounted at the tower top. The externally accessible gear allows maintenance work to be carried out at height without removing the ring.

Mining & Aggregate Equipment — Mining shovels and heavy conveyors operate in severe shock and dust environments. The sealed four-point design and 50Mn/42CrMo4 ring material are appropriate for these conditions.

Offshore & Marine Equipment — Marine deck cranes and offshore turntables can use the NBR-sealed design. For salt-spray environments, discuss surface treatment requirements with the engineering team before ordering.

Manufacturing & Quality

Heng Guan Bearing Technology Co., Ltd. makes slewing bearings in Luoyang, China. In-house CNC vertical lathes, quenching machines, gear shapers, machining centers, grinding machines, and big gear hobbing machines provide dimensional control throughout the manufacturing process.

Quality control employs coordinate measurement, vibration, and life testing devices. From raw stock to completed bearing, material is traceable. Available precision classes are P0, P6, and P5.

OEM/ODM relationships are encouraged. Custom non-standard slewing rings with changed tooth profiles, bolt patterns, or seal materials may be made from client designs or reverse-measured reference parts.

FAQ

Q: What exactly is the VSA250855-N?

A: It is an INA VSA25 heavy-series external-gear four-point contact ball slewing ring with an 855 mm raceway diameter, 755 mm bore, 997 mm outside diameter, and 80 mm height, weighing 145 kg.

Q: How is the external gear driven?

A: A pinion or worm meshes with the gear teeth on the outer ring OD from outside the ring. This keeps the drive unit accessible for servicing — the standard configuration for excavator swing drives and solar tracker worm drives.

Q: What is the difference between VSA25 and VSA20 series?

A: The VSA25 series uses an 80 mm section height versus 56 mm for VSA20, a module-9 gear versus m5–m8, and M20 fixing threads versus M12. Static axial and tooth force capacity are approximately twice that of a comparable VSA20 ring at similar outside diameter.

Q: What is the difference between VSA250855-N and VSA250755-N?

A: Both use an 80 mm section height. The VSA250855-N has an 855 mm raceway (755 × 997 × 80 mm, 145 kg, m9/z109, C0a 3,050 kN). The VSA250755-N has a 755 mm raceway (655 × 898 × 80 mm, 127.1 kg, m9/z98, C0a 2,700 kN).

Q: What bolt grade is required for mounting?

A: High-strength structural bolts of grade 10.9 or 12.9 (ISO) are required due to the high tensile loads involved. Bolts with an unthreaded shank in the shear plane should be used.

Q: How often should the bearing be re-lubricated?

A: For heavy equipment such as excavators, re-lubrication of the raceway every 100 operating hours is a common guideline. In high-humidity or dusty conditions, shorten the interval or use an automatic lubrication system to purge old grease and contaminants.

Contact Us

For pricing, availability, drawings, or technical questions about theVSA250855-N Slewing Bearings, contact Luoyang Heng Guan Bearing Technology Co., Ltd. at mia@hgb-bearing.com.