How to install and replace slew rings

NOTE: This guide is intended as a reference for competent service engineers and technicians experienced in heavy construction machinery repair. It does not replace the machine manufacturer’s workshop manual, service instructions or torque specifications. Always refer to the OEM service documentation for machine-specific procedures.

Before Replacing a Slew Ring

A failed slew ring is often a symptom of an underlying issue rather than the root cause. Before removing the slew ring assembly, it is important to identify why the original component has failed.

Common causes of slew ring failure include:

• Incorrect or insufficient lubrication
• Contaminated grease causing accelerated raceway wear
• Loose or incorrectly torqued mounting bolt
• Incorrect bolt grade or reused fixing bolt
• Excessive machine loads beyond design limit
• Worn slew pinion or incorrect gear mes
• Damage caused by impact loading or side loading
• Leaking swing gearbox washing the grease from the slew ring.

Failure to identify and correct the original cause can result in premature failure of the replacement slew ring.

Slew Ring Inspection Prior to Removal

Before dismantling, carry out a detailed inspection of the existing assembly.

• Check for Excessive Vertical Movement
• Measure slew ring clearance by positioning the machine correctly and applying controlled lifting forces to the front attachment.

Excessive vertical movement may indicate:

• Worn raceways
• Damaged rolling elements

Always compare measurements against the machine manufacturer’s allowable limits.

Removal Procedure

Step 1 Secure the Machine and Prepare for Removal

Before removing the slew ring:

• Park the machine on firm, level ground
• Fully retract hydraulic cylinders where possible
• Disconnect electrical and hydraulic components where required
• Remove any covers, guards or access panels

The upper structure must be fully supported before releasing slew ring mounting bolts.

Incorrect support can result in distortion of mounting faces or unsafe separation of components.

Step 2 Remove Mounting Bolts Correctly

During removal:

• Follow the OEM bolt removal sequence
• Inspect bolt heads and threads for damage
• Check for signs of bolt stretch or fretting
• Do not reuse bolts unless specifically approved by the manufacturer

Common failure indicators include:

• Rust staining around bolt heads
• Elongated bolt holes
• Shiny contact marks caused by movement
• Cracked bolt heads

These are signs of bolt relaxation or incorrect preload.

Before Installation:

Mounting Surface Preparation

Before installing the replacement slew ring:

• Remove all corrosion, debris and old sealant
• Check mounting faces for flatness
• Inspect for cracks or distortion
• Confirm bolt holes are clean and undamaged

Even minor contamination between the slew ring and mounting surfaces can create uneven loading and accelerate failure.

Check Associated Components

A slew ring replacement should always include inspection of related components:

• Slew Pinion
• Gearbox bearings

Checklist:

• Gear tooth wear
• Incorrect contact pattern
• Damage caused by poor lubrication
• Excessive backlash

A worn slew pinion can damage a new slew ring.

Mounting Bolts

Verify:

• Correct tensile grade
• Correct length
• Correct tightening procedure

Many excavator slew rings use high tensile metric fasteners requiring controlled tightening using:

• Torque tightening
• Torque + angle methods
• Hydraulic tensioning equipment

Always follow OEM specifications.

Installing the Replacement Slew Ring

Step 1 Confirm Correct Orientation

Before installation confirm:

• Internal and external gear arrangement
• Grease nipple position
• Mounting hole pattern
• Soft spot location and orientation – normally marked with an ‘S’

Incorrect orientation will cause premature failure of the slew ring and associated parts.

Step 2 Install & Align the Slew Ring

Carefully lower the upper structure into position.

Check:

• Correct alignment of bolt holes
• Full contact between mounting surfaces
• No trapped debris or contamination

Do not force alignment using mounting bolts.

Step 3 Tighten Fixing Bolts

Mounting bolts must be tightened using the manufacturer’s specified procedure.

Important considerations:

• Tighten in the correct cross-pattern sequence
• Apply the correct torque values
• Confirm final torque after initial operation where specified

Incorrect tightening can cause:

• Bolt loosening
• Fretting damage
• Raceway distortion
• Catastrophic slew ring failure

Lubrication Requirements

Correct lubrication is essential for slew ring service life.

Before returning the machine to operation:

• Apply the correct grade grease as pre manufacturers spec
• Ensure grease reaches the complete raceway
• Rotate the machine and recheck lubrication where possible
• Check seals and grease distribution

Common lubrication failures include:

• Over-greasing causing seal damage
• Under-greasing causing raceway wear
• Using incorrect grade grease

Final Commissioning Checks

Before releasing the machine:

✓ Check slew ring bolt torque
✓ Confirm smooth rotation in both directions
✓ Check slew gearbox operation
✓ Inspect for abnormal noise or vibration
✓ Confirm grease distribution
✓ Check gear mesh and backlash
✓ Monitor during initial operating hours

WARNING

Slew rings are safety-critical components. Incorrect installation can result in premature failure, machine damage or serious safety risks.

Replacement should only be carried out by suitably trained and competent technicians using appropriate lifting equipment and tooling.

Always follow the machine manufacturer’s workshop procedures and torque specifications.

At Plant Parts, we supply replacement slew rings for a wide range of excavators and heavy construction machinery.

Our extensive stockholding includes:

• Excavator slew rings
• Slew bearings
• Slew ring assemblies
• Replacement mounting bolts
• Associated seals and components

With access to over 2 million parts, our experienced team can help identify the correct replacement component using your machine model, serial number or existing part details.

Search for your slew ring using our Parts Finder or call the team direct on +44 (0) 1473 820910