When air bellows fail to return to their original height, this often indicates a deeper issue with the system setup. These failures may relate to pressure loss, material fatigue, or improper alignment. All air springs require consistent internal pressure to maintain their design height, stroke, and natural frequency. If a bellow with a nominal stroke of 150 mm only extends partially, the pressure regulation system must be checked. Most standard Tevema bellows are rated for 8 bar, while high-strength four-ply models can handle up to 12 bar. Failure to meet pressure requirements can prevent full extension. Always check the compressed air regulator, air inlet, and flow control valves. The air must be clean and dry to avoid inner material degradation. If the system doesn’t recover after correcting pressure, inspect mechanical alignment. Incorrect setup or twisted mounts may block vertical stroke, keeping the air bellow from reaching its full extension.
Evaluate pressure consistency and regulation
Inconsistent air pressure is one of the most common reasons for failing to reach the original extension height. Air bellows rely entirely on internal pressure to generate axial force. A typical single convolution bellow will exert 10 kN of force at 7 bar. If actual pressure is too low or fluctuates, this causes unstable operation. Check if the pressure regulator maintains output within ±0.1 bar tolerance. Internal leakages or blocked inlets can reduce effective working pressure. Ensure the system is free of oil, moisture, and dirt. If the working medium is nitrogen, confirm that all materials are compatible. For example, CIIR elastomer is ideal for chemically aggressive media. Also inspect the air inlet thread type and ensure proper engagement—common options are G1/4″, G3/8″, or G1/2. Mismatched connections reduce flow and efficiency. For critical applications, install a secondary safety valve and pressure gauge for real-time monitoring. Stable and clean air flow ensures proper bellow return after load cycles.
Inspect mechanical deformation or internal failure
Long-term use may cause mechanical deformation or failure in the rubber structure or internal reinforcements. Each air bellow consists of inner and outer rubber layers, reinforced with textile plies and steel bead rings. These components are vulcanized into a single unit, but excessive cycles or overloads may weaken them. Check for bulging, sagging, or off-center inflation—these signs suggest internal damage. Use a caliper to compare dimensions across different points; any deviation over 2 mm signals structural fatigue. Also, verify the integrity of end closures, mounting studs, and metallic bead rings. These must remain parallel and aligned. Loose parts can shift under pressure, altering the stroke path. Stainless steel components (AISI 304 or AISI 316L) offer better resistance to corrosion and deformation. If cracks, delamination, or localized wear are found, replace the unit. Continued use in damaged condition increases failure risk. Always compare actual bellow height to the listed minimum and maximum extension ranges.
Consider thermal degradation of elastomers
Temperature changes affect the flexibility and rebound characteristics of air bellows, particularly in systems exposed to heat. Elastomers like NR/SBR become brittle above 70 °C, leading to lower stroke efficiency. For higher operating temperatures, use EPDM, CIIR, or NBR, which endure up to 115 °C. Exposure beyond the rated temperature range causes hardening and micro-cracks in the rubber. This limits its ability to flex and fully expand. If your bellow operates in a heated environment, use an infrared thermometer to check surface temperature. Ensure the mounting area allows for sufficient airflow and cooling. Evaluate the change in natural frequency, which can shift as rubber stiffness increases. The system may also show increased resonance sensitivity, creating unwanted vibrations. Choose the right elastomer based on temperature and media compatibility. Always refer to technical datasheets for each compound’s working range. Consistent thermal overload reduces lifespan and causes permanent deformation. Preventive temperature control helps restore and maintain original height.
Check lateral misalignment or improper mounting
Improper mounting and lateral misalignment are key contributors to insufficient rebound height. Each Tevema air bellow has specific axial and radial tolerance values. A misalignment exceeding 2° angular or 3 mm lateral will disrupt stroke efficiency. Flexible models can absorb some offset, but only within their rated range. Misaligned mounting plates force the bellow to bend instead of extend vertically. Always verify flatness and parallelism of mounting surfaces using a feeler gauge. Torque all mounting bolts uniformly, following the recommended pattern and values. Inspect bead rings for deformation or uneven contact. If using threaded bead rings (M8, M10, or M12), ensure proper engagement depth—minimum 15 mm. Secure the air inlet so it doesn’t pull during movement. Check if the return motion is skewed or partial. Angular movement above the design spec (usually max 25°) restricts full height recovery. Correct mounting geometry and torque settings are essential to restore full rebound capacity in bellows.
Detect contamination in the air supply
Contaminants inside the air supply line reduce system efficiency and can cause air bellows to collapse or return incompletely. Oil, dust, and water can enter the chamber and damage internal surfaces. Install an inline filter with a minimum 5 µm rating to remove particles. Use a coalescing filter to eliminate oil aerosols. If water vapor is present, install a refrigerant or desiccant dryer. Moisture promotes internal corrosion and weakens the vulcanized fabric plies. Dirt can block flow channels, causing uneven expansion. Use compressed air with ISO 8573-1 Class 2 or better. Monitor pressure drop across filters to assess clogging. Replace elements on schedule to maintain air quality. For bellows operating in harsh environments, consider using stainless steel closures and EPDM rubber, both corrosion-resistant. If contamination is suspected, isolate and purge the system. Consistently clean air supply ensures reliable bellow operation and consistent height recovery under varying load conditions.
Analyze if the air bellow is oversized or undersized
Incorrect sizing of air bellows leads to poor system dynamics and unstable height recovery. A bellow that’s too large may not inflate fully, even at max pressure. A unit too small may over-extend and fatigue faster. Start by checking the required stroke, operating load, and mounting height. Compare these with the technical specs: stroke (e.g., 150 mm), force at 7 bar (e.g., 27 kN), and design height (e.g., 240 mm). Also note the natural frequency, which should match the system’s resonance profile. For example, if the system resonates at 2.5 Hz, choose a bellow with similar frequency. Oversized units offer slower response and lower efficiency. Undersized units suffer from overstress and rubber fatigue. Use the full Tevema catalog to select the correct convolution type (single, double, or triple). Ensure the elastomer and metal type match your environmental conditions. Right-sizing the bellow restores full stroke behavior and improves long-term reliability.
Replace degraded or damaged internal components
If height recovery fails despite all corrections, the internal components of the air bellow may be compromised. Vulcanized rubber can lose elasticity after repeated cycles or thermal aging. Reinforced fabric plies may separate or buckle under stress. Disassemble the unit if it’s a dismountable type. Inspect for uneven bead ring wear, cracked closures, and ruptured plies. Measure the internal diameter and compare to factory specs. A tolerance loss over 3% indicates internal fatigue. Check for signs of air leakage using a soap test or ultrasonic detector. Replace any unit showing internal damage, as partial repairs are rarely effective. Use modular bellows when possible, so damaged parts can be replaced individually. Always torque reassembled parts to spec using a calibrated wrench. Retest the unit under load to confirm full stroke recovery. Preventive replacement of worn components ensures reliable return to original height and prevents downtime in mission-critical systems.
When to contact an expert
If none of these measures solve the problem, contact a technical specialist. Some height recovery issues stem from complex system dynamics. These include vibration coupling, pressure delay, or non-linear loading. Our engineers can review application parameters and provide advanced diagnostics. Share your operating pressure, load range, stroke target, and mounting setup. We will simulate your configuration using finite element modeling and recommend the right bellow type. For custom setups, we offer elastomer variation (e.g., CIIR, EPDM, NBR), high-strength versions, and corrosion-resistant metal options. All models follow ISO guidelines and are tested for fatigue and burst pressure. If needed, we design complete actuator assemblies tailored to your installation space and performance needs. Don’t allow persistent bellow failure to reduce uptime or process quality. Our expertise in pressure mechanics and dynamic sealing helps you maintain full functional height. Partner with us for long-term operational consistency and reduced maintenance intervention.