Surface and safety
Use firm level ground, a clear zone and competent operator. Isolate before approaching pinch points and never place any body part below attachments.
Used Excavator Swing Bearing Play and Slew System Test
Measurement and diagnostic test
How to Check Swing Bearing Play on a Used Excavator
Record relative movement between the upper and lower frames, separate bearing play from pin or drivetrain movement, and use the manufacturer procedure and limit for the exact machine. The worksheet summarizes readings; it does not pass or fail a machine.
How to check excavator swing bearing play
Start with the applicable OEM procedure and a safely mounted dial indicator. Where the procedure calls for multiple orientations, record each position and repeat the same loading method. Do not diagnose the bearing from a single boom-rocking test or apply a universal millimetre limit.
Build a repeatable setup before reading a number
Indicator point
Fix a stable base on the lower frame and read against a clean upper-frame surface. Mark the point for repetition.
Consistent loading
Use the manual method: repeat attachment position, ground contact, lift and rpm without shock loading.
Four orientations
Measure at 0°, 90°, 180° and 270°. A local difference can indicate race, structure or mounting rather than uniform wear.
Repeatability
Run two cycles per position. If readings do not repeat, investigate loose setup, pins, ground movement or inconsistent technique.
OEM reference
Record model, suffix, serial, temperature and procedure. Compare with the service manual or dealer measurement.
Do not merge four systems with similar symptoms
| System | Clue | Separating test |
|---|---|---|
| Swing bearing | Relative vertical movement, noise or roughness following the ring. | Indicator, repeated positions, lubrication and OEM limit. |
| Ring gear/pinion and gearbox | Clunk on reversal, delay or noise under torque. | Backlash procedure, gearbox oil, teeth and noise pattern. |
| Swing brake or valve | Slope drift, abrupt stop, delay or overshoot. | Controlled functional test, pressure and hydraulic diagnosis. |
| Pins and attachment | Bucket or boom moves while the upper frame remains stable. | Side observer and separate measurement at each joint. |
| Frame or mounting bolts | Irregular movement, fretting marks, loose bolts or distorted surfaces. | Mounting inspection, manual torque and structural assessment. |
Full-rotation dynamic test
- 1Warm the system and clear the full 360-degree operating radius.
- 2Swing one slow revolution each way and listen for a sector-dependent sound.
- 3Repeat at moderate speed; compare acceleration, stopping and reversal without abrupt inputs.
- 4Use only the manufacturer's safe method for any slope check; never improvise a drift test.
- 5After testing, inspect temperature, leaks, gearbox oil condition/level and displaced grease.
- 6Keep one continuous video of monitor, upper structure and sound tied to the serial number.
Decision ladder
A. Repeatable data
Consistent readings, even pattern and result inside a documented OEM specification.
Continue with oil, bolt and dynamic checks.B. Incomplete data
One reading only, no marked point, variable load or no applicable manual.
Repeat; do not label good or bad.C. Local difference
One orientation differs clearly, sector noise or movement marks appear.
Diagnose race, mount, frame and gear before final pricing.D. Severe symptom
Heavy knock, binding, loose bolt, leak, uncontrolled drift or result above the OEM limit.
Stop operation and obtain professional repair scope and estimate.Official references
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01Komatsu: maintenance and repair programs
Service categories support the inspection scope; the allowable movement must come from the exact-model procedure.
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02Komatsu: technical and field services
Service categories support the inspection scope; the allowable movement must come from the exact-model procedure.
Swing bearing and slew-system questions
What is the maximum acceptable play?
There is no number valid for every excavator. Use model, suffix, serial, configuration and the OEM manual procedure; this tool only summarises readings.
Can I measure by lifting the machine with the boom?
Only when the manufacturer procedure and safety controls permit it. Position, load and measurement point materially change the result.
Is every reversal clunk the swing bearing?
No. It may come from gears, gearbox, brake/valve, pins or mounting. Locate the actual movement before attributing it.
Does fresh grease mean a good bearing?
No. It proves recent greasing, not internal condition. Check distribution, contamination, expulsion, noise and measurement.
Why measure four positions?
Wear, mounting movement or damage can be sector-specific. One reading can miss the largest movement.
What remote evidence should I receive?
One video of indicator setup, marked point, four orientations, two cycles, serial, temperature and the OEM limit page used.
From a bearing reading to a buying decision
Bearing play is one part of an inspection, not a complete assessment of the machine. Connect the reading to the selected unit, any required work and the import budget.
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1. Identify the unit
Review the CAT 320D listing and request readings tied to that machine and the applicable OEM procedure.
CAT 320DFull inspection checklist -
2. Agree the work
Watch a workshop example; confirm repairs, parts and post-work tests for your order in writing.
CAT 320D workshop videoCondition options -
3. Verify shipment and cost
Review a real shipment with protected evidence, then request your own destination-port quotation.
Guyana export caseFOB checklist
The linked videos and cases are public examples of activity and fulfillment. They do not replace current evidence for your unit or the terms of your order. Actual export dates and customer identifiers are not published.
Send the model, job, preferred condition and destination port to confirm availability, exact-unit evidence and an itemized quotation.
Request evidence & quotePublished and reviewed: 19 August 2026 · YUANJIAN MACHINERY INTERNATIONAL TRADING LIMITED