81M8-01020 81M8-01021 Swing Bearing (572x800x70mm) for Hyundai R55-7

81M8-01020 Swing Bearing for Hyundai R55-7 Excavator

The 81M8-01020 / 81M8-01021 swing bearing is used for Hyundai excavator swing system applications. It is also searched as a slewing ring, swing circle, turntable bearing or excavator rotation bearing for Hyundai R55-7 repair.

This page focuses on 81M8-01020 and 81M8-01021 as the main part numbers. Before ordering, the removed swing bearing should be checked by old bearing number, inner diameter, outer diameter, height, gear teeth, bolt hole layout and machine serial number.

Swing System Function

The swing bearing supports the upper structure of the excavator and allows the house assembly to rotate smoothly on the lower frame. It carries axial load, radial load and tilting moment during digging, loading, grading and travel-position rotation.

For a compact excavator such as the Hyundai R55-7, swing bearing wear can affect rotation stability, gear mesh and operator control. If looseness, abnormal noise or uneven rotation appears, the bearing, swing motor pinion, mounting bolts and lubrication condition should be checked together.

Size and Identification Notes

The common size reference for this bearing is 572 x 800 x 70 mm. This dimension is useful for initial checking, but final confirmation should not rely on size alone. Swing bearings with similar outside dimensions may still have different bolt holes, gear teeth, raceway design or seal structure.

Reference Number Notes

The main numbers for this page are 81M8-01020 and 81M8-01021. Some Hyundai swing bearing catalogs may also show related formats such as 81M801020, 81M801021 or 81M8-01021GG in R55 series references.

These related formats should be used for catalog checking only. They should not be treated as automatic interchange confirmation unless the old bearing number, dimensions, bolt hole pattern, gear teeth and machine serial number are checked.

How to Identify the Correct Swing Bearing

• Check whether the old bearing number matches 81M8-01020 or 81M8-01021.

• Measure the inner diameter, outer diameter and total height before ordering.

• Count the gear teeth and compare the gear direction with the removed bearing.

• Check the inner ring and outer ring bolt hole quantity, diameter and spacing.

• Inspect the seal groove, grease port position and raceway condition.

• Confirm the Hyundai machine model and serial number when the old part number is not readable.

Common Failure Symptoms

• Upper structure wobble during swing operation or when changing direction.

• Abnormal knocking, clicking or grinding noise around the swing bearing area.

• Uneven or jerky rotation caused by worn raceway, damaged gear teeth or poor lubrication.

• Grease leakage or damaged seals around the bearing ring.

• Loose mounting bolts or repeated bolt failure caused by bearing wear or improper tightening.

• Pinion gear wear caused by incorrect gear mesh or excessive bearing clearance.

Troubleshooting Before Replacement

Before replacing the 81M8-01020 swing bearing, inspect the complete swing system. Swing noise or looseness may be caused by the bearing itself, but it may also come from loose bolts, worn swing motor pinion, damaged reducer parts, poor lubrication or frame deformation.

• Check swing bearing axial and radial clearance before disassembly.

• Inspect the swing motor pinion and bearing gear teeth for uneven wear.

• Check mounting bolts for looseness, stretching, corrosion or thread damage.

• Inspect grease condition, grease passages and sealing condition.

• Check whether the upper frame or lower frame mounting surface is damaged or uneven.

Installation and Maintenance Notes

• Support the upper structure safely before removing the old swing bearing.

• Clean the upper and lower mounting surfaces before installation.

• Do not install the new bearing on a bent, cracked or uneven mounting surface.

• Use the correct mounting bolts and tighten them in a cross pattern according to service procedure.

• Check gear mesh between the slewing ring and swing motor pinion after installation.

• Apply suitable grease and confirm that grease reaches the raceway evenly.

• After installation, rotate the upper structure slowly and check for abnormal noise, vibration or uneven movement.

Fitment Check Before Ordering

To reduce wrong orders, please send the old bearing number, Hyundai machine model, machine serial number, inner diameter, outer diameter, height, gear teeth count, bolt hole photos, full bearing photos and any visible part number marks before quotation.

FAQ

Q: What is 81M8-01020?

81M8-01020 is a Hyundai swing bearing or slewing ring reference used for excavator swing system applications, commonly associated with Hyundai R55-7 references.

Q: Is 81M8-01021 related to 81M8-01020?

81M8-01021 appears in related Hyundai R55 series swing bearing references. It should be checked by old bearing number, dimensions, gear teeth and bolt hole layout before being treated as the same replacement group.

Q: What size should be checked for this bearing?

The common size reference is 572 x 800 x 70 mm. Inner diameter, outer diameter, height, gear teeth and bolt holes should still be measured before ordering.

Q: Which Hyundai model is commonly referenced?

Hyundai R55-7 is the main model reference for this page. Related R55 series references should be confirmed by part number and physical bearing configuration.

Q: What causes early swing bearing failure?

Early failure may be caused by poor lubrication, loose mounting bolts, contaminated grease, damaged seals, worn swing motor pinion, excessive impact load or uneven mounting surfaces.