Volvo CE Slewing Ring & Swing Bearing Guide: Parts, Wear Signs & Replacement

What Is a Slewing Ring (Swing Bearing)?

The slewing ring — also called the swing bearing or slewing bearing — is the large-diameter rolling-element bearing that allows the upper structure of an excavator to rotate 360° relative to the undercarriage. It transmits all forces between the upper and lower structures: vertical loads from the machine weight and bucket payload, horizontal forces from digging, and moment loads from long reach work. On a 20-tonne excavator, the slewing ring can measure 1.2–1.6 metres in diameter. VMP Spares stocks slewing rings for the full Volvo CE excavator range.

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How to Identify Slewing Ring Wear

Slewing ring failure is gradual — when caught early, replacement is straightforward. When caught late, it can damage the mounting structures on both upper and lower frames. Inspect every 500 hours for these warning signs:

Greasing the Slewing Ring — Critical Maintenance

The single most important maintenance task for slewing ring longevity is correct greasing. Volvo recommends greasing the slewing ring every 50–100 hours under normal conditions, and every 25 hours in dusty or wet environments. The correct procedure: rotate the upper structure 90° between grease applications until all grease nipples have been serviced, then rotate slowly to distribute grease evenly around the full circumference. Use only Volvo-specified lithium-complex grease — never substitute general-purpose grease.

Slewing Ring Part Numbers — Volvo CE Excavators

Swing Motor — Working with the Slewing Ring

The swing motor (also called slew motor) drives the swing pinion that meshes with the internal gear of the slewing ring. When a slewing ring is worn, the swing motor is often inspected simultaneously. Common swing motor parts that need replacement alongside the slewing ring include the swing pinion gear, motor shaft seal kit, and motor housing O-rings.

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Slewing Ring Replacement Procedure (Overview)

Replacing a slewing ring is a significant workshop job requiring proper lifting equipment and alignment tools. The key steps are: drain the hydraulic system, remove the upper structure, unbolt the old ring, clean the mounting surfaces, check flatness (max 0.15mm deviation), fit the new ring with new bolts torqued to spec (typically 400–800 Nm depending on model), and re-align the swing pinion backlash to 0.2–0.4mm. Always use new bolts — slewing ring bolts are torque-to-yield and should not be reused.