Deformation and Bulging of Jack Rubber Buffer Blocks: Causes and Solutions
Jack rubber buffer blocks are designed to absorb impact, reduce vibration, and distribute load evenly during lifting operations. Deformation and bulging are common failure phenomena that not only reduce buffering performance but also pose potential safety risks. A clear understanding of the causes and appropriate corrective measures is essential.
1. Excessive Compressive Load
When the applied load exceeds the design capacity of the rubber buffer block, the internal rubber structure is forced to flow laterally. This leads to permanent deformation and visible bulging at the sides. Repeated overloading accelerates internal structural damage and significantly shortens service life.
2. Long-Term Static Compression
Prolonged static loading causes rubber creep and compression set. Over time, the material loses its ability to recover elastically, resulting in thickness reduction and lateral expansion. This phenomenon is especially common when the jack remains under load for extended periods without unloading.
3. Improper Rubber Hardness Selection
If the rubber hardness is too low for the working load, the material cannot effectively resist compressive stress. Soft rubber materials tend to deform excessively, causing bulging even under normal operating conditions. Incorrect hardness selection is a frequent design-related cause of this issue.
4. Inadequate Structural Constraint
Rubber buffer blocks without sufficient lateral confinement allow the material to expand freely under compression. The absence of metal plates, fiber reinforcement, or sidewalls increases the risk of bulging, particularly in high-load applications.
5. Material Aging and Degradation
Aging due to heat, oxygen, ozone, or chemical exposure reduces rubber strength and elasticity. Degraded rubber exhibits lower resistance to deformation and is more prone to creep and bulging under load.
6. Manufacturing and Quality Factors
Non-uniform rubber density, improper filler dispersion, or insufficient vulcanization can lead to weak zones within the block. These areas deform more easily under compression, resulting in localized bulging.
Preventive and Corrective Measures
To prevent deformation and bulging, rubber buffer blocks should be designed with adequate load capacity and appropriate hardness, typically within a suitable Shore A range based on application requirements. Structural reinforcement or lateral constraints can effectively limit rubber flow. Proper material selection and formulation, strict control of vulcanization processes, and avoidance of long-term overloading are also essential. Regular inspection and timely replacement of deformed blocks help maintain lifting safety.
Conclusion
Deformation and bulging of jack rubber buffer blocks are mainly caused by overloading, long-term static compression, improper hardness selection, lack of structural restraint, material aging, and manufacturing defects. Through optimized material selection, improved structural design, controlled operating conditions, and effective maintenance, these issues can be significantly reduced.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers, 2012.
ASTM D395 – Standard Test Methods for Rubber Property—Compression Set.
Lake, G. J. “Fatigue and Fracture of Elastomers.” Rubber Chemistry and Technology, 2000.
ISO 7619-1 – Rubber, Vulcanized or Thermoplastic — Determination of Indentation Hardness.
