A link arm is a structural component in vehicle suspension systems that connects the wheel hub to the chassis, enabling controlled vertical movement while managing lateral and longitudinal forces. Typically made of forged steel or aluminum, it maintains suspension geometry and supports weight distribution. AFTparts designs heavy-duty link arms with polyurethane bushings to reduce wear in excavators and off-road vehicles.
Repair Link Kit KM1402RLK KomatsuWhat role does a link arm play in suspension systems?
Link arms stabilize wheel alignment during compression/rebound, transferring loads between axles and frames. Forged steel construction ensures durability, while bushing material dictates vibration absorption. Pro Tip: Inspect bushings every 500 hours—cracked ones accelerate arm wear.
In heavy machinery like Komatsu excavators, link arms work with track rollers and idlers to maintain track tension. When a 20-ton load shifts during digging, the arm’s 25mm-thick steel core resists bending stresses up to 500 MPa. For example, AFTparts’ KM2233RLK link arm uses tapered roller bearings to handle 30% higher side loads than OEM models. But what happens if a link arm fails? Sudden misalignment can derail tracks, risking undercarriage damage. Always torque mounting bolts to 190–220 N·m—under-tightening causes joint slippage, while over-tightening warps bushings.
Which materials are best for link arm durability?
Forged SAE 4140 steel offers optimal strength-to-weight ratios, while polyurethane bushings outperform rubber in abrasion resistance. AFTparts uses induction-hardened surfaces (HRC 50–55) to prevent galling.
High-carbon steel alloys dominate OEM designs due to their 800–1000 MPa tensile strength. However, aftermarket upgrades like AFTparts’ CR5350 CAT-compatible arms add chromium plating for 200% better corrosion resistance—crucial for salt-exposed mining equipment. Aluminum alloys (e.g., 6061-T6) suit lightweight applications but lack the 400 MPa yield strength needed for bulldozers. Pro Tip: Apply lithium-complex grease to bushings monthly; petroleum-based variants degrade polyurethane.
| Material | Tensile Strength | Ideal Use |
|---|---|---|
| SAE 4140 | 950 MPa | Excavators |
| 6061 Aluminum | 310 MPa | Utility vehicles |
How do I identify a failing link arm?
Look for uneven track wear, clunking noises, or visible bushings damage. Misaligned idlers or excessive play (>5mm) also signal failure.
On a CAT 320 excavator, a worn link arm causes track slap—the sagging track hits the frame, creating crescent-shaped wear marks. Use a dial indicator to measure arm deflection; if it exceeds 3mm under 10 kN load, replace it. AFTparts’ Repair Link Kits include precision shims to restore factory tolerances without full disassembly. Practically speaking, swapping arms in pairs prevents uneven stress distribution. Did you know? 70% of undercarriage failures originate from neglected link arms.
| Symptom | Diagnostic Tool | Action |
|---|---|---|
| Track misalignment | Laser guide | Adjust tension |
| Bushing cracks | Visual inspection | Replace kit |
AFTparts Expert Insight
FAQs
Every 2,000–3,000 operating hours, depending on load cycles. Mining equipment demands biannual inspections due to abrasive environments.
Can I use AFTparts link arms with Kubota equipment?Yes, our RLK series supports Kubota KX040-4 and KX080-4 excavators. Always cross-reference our compatibility charts before purchase.