1.Fracture and Cracking
Leaf spring fractures typically occur in the main leaf or inner layers, presenting as visible cracks or complete breakage.
Primary Causes:
–Overloading & Fatigue: Prolonged heavy loads or repeated impacts exceed the spring’s fatigue limit, especially in the main leaf bear most of the load.
–Material & Manufacturing Defects: Inferior spring steel (e.g., insufficient SUP9 or 50CrVA grade) or flawed heat treatment (e.g., inadequate quenching or tempering) reduce material toughness.
–Improper Installation/Maintenance: Over-tightened or loose U-bolts cause uneven stress distribution, while lack of lubrication between leaves increases friction and stress concentration.
2. Deformation and Arcuate Loss
Leaf springs may bend, twist, or lose their arch shape, affecting suspension stiffness and vehicle stability.
Primary Causes:
–Abnormal Loading: Frequent operation on rough terrain or misbalanced cargo shifts cause localized overstress.
–Thermal Damage: Proximity to exhaust systems or high-temperature components weakens steel elasticity, leading to plastic deformation.
–Aging: Long-term use reduces the steel’s elastic modulus, causing permanent deformation.
3. Loosening and Abnormal Noise
Metallic rattling or squeaking during driving, often due to loose connections or worn components.
Primary Causes:
–Loose Fasteners: U-bolts, center bolts, or spring clips loosen, allowing leaves or axle connections to shift and rub.
–Worn Bushings: Degraded rubber or polyurethane bushings in shackles or eyelets create excessive clearance, leading to vibration-induced noise.
–Lubrication Failure: Dried or missing grease between leaves increases friction, causing squeaks and accelerating wear.
4. Wear and Corrosion
Visible grooves, rust spots, or thickness reduction on leaf surfaces.
Primary Causes:
–Environmental Factors: Exposure to moisture, salt (e.g., winter roads), or corrosive chemicals causes rust; mud and debris in leaf gaps exacerbate abrasive wear.
–Abnormal Inter-Leaf Sliding: Lack of lubrication or deformed leaves lead to uneven sliding, creating grooves or flat spots on leaf surfaces.
5. Elasticity Degradation
Reduced load-bearing capacity, manifested by abnormal vehicle ride height (e.g., sagging) under no load or full load.
Primary Causes:
–Material Fatigue: Repeated high-frequency vibrations or cyclic loading damage the steel’s crystalline structure, lowering its elastic limit.
–Heat Treatment Defects: Insufficient hardening or excessive tempering reduces the spring’s modulus of elasticity, impairing its ability to return to its original shape.
6. Assembly Misalignment
Leaf springs shift from their correct position on the axle, causing tire uneven wear or driving deviation.
Primary Causes:
–Installation Errors: Misaligned center bolt holes or incorrect U-bolt tightening sequences during replacement lead to leaf mispositioning.
–Damaged Support Components: Deformed axle spring seats or broken shackle brackets force the spring out of alignment.
Conclusion: Impact and Prevention
Leaf spring faults in heavy trucks primarily stem from excessive loading, material flaws, maintenance neglect, and environmental factors. Regular inspections (e.g., visual crack checks, arch height measurements, noise diagnostics) and proactive maintenance (lubrication, fastener tightening, rust protection) are crucial to mitigating risks. For heavy-duty applications, prioritizing quality materials, adhering to load limits, and addressing issues promptly can significantly extend leaf spring lifespan and ensure operational safety.
Post time: Jun-19-2025
