Excavator Undercarriage Parts: A Buyer’s Guide for Wholesale Procurement
When it comes to excavator maintenance or resale, few things are more critical than choosing the right undercarriage parts. The undercarriage system is responsible for ground movement, machine balance, and weight distribution. Worn or mismatched parts can result in costly downtime and even safety hazards.
In this guide, we’ll break down the major undercarriage components section by section, helping you understand what to check, how to match replacements properly, and how to ensure OEM-equivalent fitment.
1. Track Chain Assembly – Know Your Pitch and Links
The track chain (or track link assembly) is the foundation of your machine’s mobility. When replacing it, you need to match:
- Link pitch: This is the distance between pin centers. Common sizes include 135mm, 154mm, and 175mm.
- Link height and width: These dimensions affect ground clearance and shoe compatibility.
- Number of links: This must match your specific model's track length.
- Pin & bushing hardness: For high-wear applications, look for parts with induction-hardened or forged pins.
💡 Tip: Always count the number of links on one side and measure pitch manually before placing an order.
2. Carrier Rollers – Match Mounting & Shaft Diameter
Carrier rollers (top rollers) support the upper portion of the track and guide it in a straight line. Matching parameters include:
- Mounting bolt pattern and hole spacing
- Shaft diameter and bearing type
- Machine tonnage class (e.g., 5-7 ton, 20-25 ton)
For smoother performance and reduced noise, go for rollers with sealed, oil-lubricated designs — especially in high-moisture areas.
3. Track Rollers – Load-Bearing Essentials
These lower rollers carry the full weight of the machine. Mismatch here can result in misalignment, premature wear, or even derailment.
Key matching specs:
- Flange shape: Single or double flange, depending on your track frame.
- Roller width and body style: Ensure consistent contact with the chain.
- OEM reference number or casting code, if available.
Heavy-duty rollers may use forged shells or upgraded seals to survive rocky or abrasive terrain.
4. Sprockets – Tooth Profile Is Everything
The drive sprocket transfers power from the final drive to the tracks. Match the following to ensure smooth engagement:
- Number of teeth: Exact match required for chain compatibility.
- Hub dimensions and bolt pattern: Misfit can damage both the sprocket and final drive.
- Tooth profile and hardness: Ensure heat-treated or machined teeth for better wear life.
🔧 Pro tip: Replacing sprockets without checking chain wear can lead to early failure. Always inspect both together.
5. Idlers – Spring-Tensioned and Model-Specific
The front idler keeps proper tension on the track chain. Replacement selection must be based on:
- Center distance to frame
- Bracket style and bolt positions
- Diameter and track shoe clearance
On heavy excavators, idlers often use recoil springs or hydraulic cylinders — check specs carefully before replacing.
6. Rubber Tracks or Shoes – Surface-Specific Matching
If you're using rubber tracks or bolt-on rubber pads, be sure to match:
- Shoe width and bolt spacing
- Track pattern and application type (aggressive vs. low-vibration)
- Track tension capacity of the undercarriage
Rubber tracks for mini-excavators have different lug profiles and embedded steel cores — don’t interchange with steel-chain setups.
7. Hydraulic Cylinders & Slewing Bearing – Extended Undercarriage Needs
Though not traditional undercarriage components, the arm, boom, and bucket cylinders, as well as the slewing ring bearing, are closely tied to machine motion and balance. Match them using:
- Stroke and bore dimensions
- Rod diameter and mounting ends
- Seal type for hydraulic environments, especially in cold or abrasive settings.
Final Advice: Match by Specs, Not Just Brand
Many excavator models share platforms or evolve over time (e.g., Komatsu PC200-6 vs PC200-7). Always double-check:
✅ Machine serial number
✅ Casting or OEM number on your existing part
✅ Measured specs if no data is available
At KINTON PARTS, we offer full undercarriage solutions for brands including Caterpillar, Komatsu, Hitachi, Volvo, Doosan, and more, with custom sourcing options available.
Need Help Matching a Part?
Check out the visual guide below (← insert your labeled machine image here) and contact us with your machine model, tonnage, or part number — we’ll do the matching for you.
