Failures of Jack Rubber Blocks in High and Low Temperature Environments
Jack rubber blocks are essential components for cushioning, vibration reduction, and load distribution during lifting operations. Extreme temperatures, whether high or low, can significantly affect the mechanical properties, durability, and safety of these rubber blocks. Understanding the failure mechanisms and implementing preventive measures are crucial for reliable operation.
1. High-Temperature Environment Failures
Thermal Aging: Prolonged exposure to high temperatures accelerates oxidative aging, causing molecular chain scission and increased crosslinking. This results in hardening, reduced elasticity, brittleness, and surface cracking.
Compression Set: Elevated temperatures increase the rate of permanent deformation under static load, leading to thickness reduction and impaired shock absorption.
Chemical Sensitivity: High temperatures can enhance the effects of oils, fuels, or other chemicals, causing swelling, softening, or further degradation of the rubber.
Preventive Measures: Use heat-resistant rubber compounds such as silicone or high-temperature-rated polyurethane. Avoid continuous operation at temperatures exceeding the rubber’s thermal limits, and apply protective coatings if necessary.
2. Low-Temperature Environment Failures
Hardening and Loss of Flexibility: At low temperatures, rubber stiffness increases, reducing its ability to absorb impact and causing it to behave in a brittle manner.
Cracking and Fracture: Brittle rubber is more prone to microcracking or “tortoise shell” cracks under impact or load cycling.
Freezing of Embedded Fluids: In some composite blocks or bonded systems, entrapped moisture can freeze, causing internal stress and delamination.
Preventive Measures: Select low-temperature-resistant materials such as EPDM, nitrile (NBR), or specially formulated polyurethane. Precondition rubber blocks in extremely cold environments and avoid sudden high-load impacts.
3. Combined High-Low Temperature Cycling
Repeated thermal cycling between high and low temperatures can induce differential expansion and contraction between rubber and bonded metal parts, causing delamination, debonding, or cumulative stress damage. Proper material selection and design with suitable thermal expansion allowances are necessary to mitigate such failures.
4. Operational and Maintenance Considerations
Avoid overloading in extreme temperature conditions.
Inspect rubber blocks regularly for cracks, hardening, or bulging.
Replace aged or deformed blocks to maintain safe jack performance.
Store spare blocks in temperature-controlled environments to preserve mechanical properties.
Conclusion
Failures of jack rubber blocks in high and low temperature environments are primarily caused by thermal aging, loss of elasticity, brittleness, cracking, and debonding. By selecting appropriate temperature-resistant materials, controlling operational loads, and conducting regular inspections, the service life and reliability of jack rubber blocks can be significantly improved.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers, 2012.
ASTM D573 – Standard Test Method for Rubber—Deterioration in an Air Oven.
ASTM D412 – Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension.
Lake, G. J. “Fatigue and Fracture of Elastomers.” Rubber Chemistry and Technology, 2000.
