Rubber pads used in hydraulic and mechanical jacks are critical for stability, load distribution, and anti-slip performance. However, over time, these pads can develop cracks, lose elasticity, or become brittle, compromising safety. Understanding the causes of cracking and aging is essential for improving material selection, design, and maintenance practices.
1. Environmental Degradation
Rubber pads are sensitive to environmental factors:
UV radiation accelerates polymer chain breakdown, causing surface cracking and discoloration.
Oxygen and ozone exposure lead to oxidative degradation, forming micro-cracks on the surface.
Temperature extremes: high heat softens rubber and accelerates chemical aging, while low temperatures can make rubber brittle.
Moisture and humidity can induce hydrolytic degradation in some nylon-filled or reinforced rubber compounds.
2. Mechanical Stress and Fatigue
Repeated loading and unloading cycles contribute to mechanical aging:
High compressive stress from heavy loads can exceed the rubber’s elastic limit, causing permanent deformation.
Shear and lateral forces during uneven jack operation generate micro-tears that propagate over time.
Vibration or impact from uneven surfaces increases internal stress concentration, accelerating fatigue-induced cracking.
3. Material Formulation Issues
The rubber compound itself plays a significant role:
Low-quality or under-cured rubber exhibits poor elasticity and resilience.
Inappropriate filler content (e.g., insufficient carbon black or silica) reduces wear resistance and crack resistance.
Rubber blends not optimized for thermal or UV resistance degrade faster in outdoor or industrial environments.
4. Manufacturing and Curing Defects
Defects introduced during production can initiate premature aging:
Uneven vulcanization or incomplete cross-linking reduces tensile strength and tear resistance.
Entrapped air bubbles or voids act as stress concentrators under load.
Poor bonding at the interface between rubber and metal base can allow stress accumulation, leading to cracking.
5. Chemical Exposure
Contact with oils, fuels, solvents, or cleaning agents can deteriorate rubber:
Swelling or softening occurs in incompatible chemicals.
Repeated chemical exposure accelerates surface fissures and reduces adhesion to the jack base.
6. Ageing Over Time
Even under ideal use, rubber naturally undergoes thermo-oxidative aging, resulting in:
Loss of elasticity
Surface hardening and cracking
Reduced friction and anti-slip performance
This is particularly critical for pads in long-term storage or low-use scenarios.
Conclusion
Cracking and aging of jack rubber pads result from a combination of environmental exposure, mechanical fatigue, material formulation, manufacturing defects, chemical interactions, and natural aging. Effective mitigation requires high-quality rubber compounds, optimized vulcanization, protective coatings, environmental control, and periodic inspection. Proper maintenance and design adjustments can significantly extend the service life of rubber pads while maintaining safety and performance.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers.
ISO 188 – Rubber, Vulcanized or Thermoplastic — Accelerated Ageing and Heat Resistance.
Lake, G. J., & Lindley, P. B. (1980). “Fatigue and Fracture of Elastomers.” Journal of Applied Polymer Science.
Rivlin, R. S. (1948). “The Mechanics of Rubber Elasticity.” Proceedings of the Physical Society.
