How to Identify the Correct Pins & Bushings for Your Excavator
How to Identify the Correct Pins & Bushings for Your Excavator
When your excavator’s pins and bushings start to loosen, squeak, or show visible wear, it’s a clear signal: it’s time to replace them. But with dozens of pin sizes, machine models, and wear conditions, choosing the correct replacement can feel overwhelming, especially when you’re dealing with different OEMs like CAT, Volvo, Deere, Doosan, or Hitachi.
The good news? Once you know exactly what to measure (and how to measure it correctly), identifying the right pin and bushing becomes a straightforward process. Here’s a step-by-step guide to help you confidently choose the correct excavator wear parts every time.
Why Proper Identification Matters
Pins and bushings are central to your excavator’s linkage system. If the wrong size is installed, even by a small margin, you can experience:
- Premature wear
- Misalignment in the bucket or linkage
- Knock or play in the joints
- Increased stress on cylinders and H-links
Accurate identification protects both your machine and your wallet.
Step 1: Identify the Pin Location
Each pin on an excavator serves a specific connection point, and each location has unique dimensions. Start by determining where the pin or bushing is being replaced:
- Bucket to H-Link
- Bucket to Arm (Stick)
- Arm Cylinder to Boom
- Boom Cylinder to Boom Base
- Track Adjuster Components
Knowing the location narrows down the possible part numbers dramatically, especially when referencing model-specific charts like a Volvo CAT pin chart or OEM diagrams.
Step 2: Measure the Pin Diameter (The Most Critical Step)
Use a digital caliper for accurate results.
How to measure bucket pins correctly:
- Measure the outer diameter (OD) of the pin at the unworn center section, not near the ends where wear is the worst.
- If wear is significant, take multiple measurements and record the largest one.
- Common sizes range from 35mm to 80+ mm, depending on the excavator size.
For example, a Volvo EC250D may use pin diameters around 60mm, while a compact excavator might use 35–40mm.
Step 3: Measure the Pin Length
Pin length varies widely even between machines with the same pin diameter.
To take the correct measurement:
- Measure end-to-end, including flanges if the pin has built-in collars.
- If the pin includes grease pathways, note the location and style of the holes.
This helps ensure compatibility with OEM-style lubrication systems.
Step 4: Identify Grease Hole Style and Placement
Different OEM brands use different lubrication methods.
Pin designs may include:
- Single grease hole
- Double grease holes
- Offset hole patterns
- Grease grooves or internal channels
Matching the lubrication path prevents dry spots and uneven wear.
Step 5: Measure Bushing Inside & Outside Diameters
Bushings require two measurements:
1. Inside Diameter (ID)
This must match the pin diameter—usually with a precision fit.
2. Outside Diameter (OD)
This must match the bore of the component (boom, arm, H-link, etc.).
3. Bushing Length
Measure from edge to edge. Length varies depending on the linkage design.
Accurate bushing measurements protect against spinning, walking out, or cracking under load.
Step 6: Check OEM Part Numbers (If Available)
If your machine’s serial number plate is readable, you can often match:
- OEM pin and bushing part numbers
- Updated supersessions
- Variants for different linkage setups
For example:
A Volvo EC220D may use multiple bucket pin options depending on linkage style (S-type coupler vs direct pin-on).
Step 7: Compare Against an Excavator Pin Size Guide
Once all measurements are taken, compare them to a trusted excavator pin size guide or supplier chart. These guides match:
- Machine model
- Pin location
- Part number
- Dimensions
- Compatible aftermarket options
This ensures you’re selecting the correct part—even if the old pin is worn down.
Step 8: Verify Tolerance and Fit
Even a 1–2 mm difference can cause:
- Excessive play
- Binding
- Accelerated wear
When in doubt, choose the measurement that matches the OEM spec, not the worn measurement from your old parts.
Bonus: Signs Your Pins & Bushings Need Replacement
You may need new parts if you notice:
- Clunking or knocking noises
- Gaps between pin and bore
- Uneven bucket movement
- Visible scoring or pitting
- Increased grease consumption
Replacing pins and bushings early prevents expensive structural repairs later.
Final Thoughts
Identifying the correct excavator pins and bushings doesn’t have to be complicated. With accurate measurements, an understanding of pin locations, and the right reference charts, you can confidently choose the correct parts for Volvo, CAT, Deere, Hitachi, Doosan, and all major brands.
Whether you’re rebuilding a bucket linkage or prepping equipment for a busy season, choosing the right wear parts ensures safety, performance, and longer machine life.