Bell Mounts

Bell mounts are just one of many types of vibration isolators available on the market, but they stand out for their compact design, ease of installation, and balanced vibration control. To understand where bell mounts excel, it’s useful to compare them with other common isolator types such as rubber pads, spring isolators, and air mounts.

1. Bell mounts vs. rubber isolation pads

Rubber pads are low-cost and easy to install, making them popular in residential or lightweight HVAC setups. However, they typically only provide basic vertical isolation and lack the structural support of bell mounts. In contrast, bell mounts offer controlled vibration reduction in multiple directions, especially under dynamic loads, making them more reliable in industrial and mechanical systems.

2. Bell mounts vs. spring isolators

Spring isolators are ideal for heavy machinery with low-frequency vibration, such as large AHUs or chillers. They provide excellent vertical isolation, but they are bulkier and more expensive. Bell mounts are better suited for medium-frequency applications and tight spaces where spring isolators may not fit. They also require less maintenance and offer more stable damping under fluctuating loads.

3. Bell mounts vs. air mounts

Air isolators offer high-performance active or semi-active vibration control, often used in precision equipment like lab instruments. However, they are complex, costly, and sensitive to environmental changes. Bell mounts, while passive, are robust, cost-effective, and easier to deploy across various industries, including marine, HVAC, and mobile equipment.

4. Comparison summary

Bell mounts offer a practical middle ground, combining good vibration control, durability, and space efficiency—making them a smart choice for a wide range of general-purpose isolation needs.

Bell mounts are composed of two main parts: the internal rubber element and the external metal housing. The selection of materials for these components is crucial, as it directly affects the mount’s performance, durability, and suitability for specific environments or applications.

1. Rubber materials

The core of a bell mount is the rubber component, responsible for vibration damping and shock absorption. Common rubber materials include:

• Natural rubber
  Known for its excellent elasticity and energy absorption capabilities. It’s ideal for general-purpose industrial equipment where oil or chemical exposure is minimal.

• Neoprene rubber
  Offers better resistance to oils, chemicals, ozone, and aging. Frequently used in HVAC, automotive, and marine environments where exposure to harsh conditions is expected.

• EPDM (Ethylene Propylene Diene Monomer)
  Suitable for outdoor and high-temperature applications due to its strong resistance to weathering, UV, and heat.

Each rubber type is available in various hardness ratings (Shore A), typically ranging from 40 to 70, depending on load and vibration frequency requirements.

2. Metal housing materials

The bell-shaped outer casing is typically made of durable metals that provide structural support and protect the rubber inside. Common options include:

• Galvanized steel
  Cost-effective and corrosion-resistant, suitable for most indoor and covered outdoor applications.

• Stainless steel
  Offers superior corrosion resistance in wet or marine environments. Often used in coastal installations or food-grade equipment.

• Aluminum
  Lightweight and corrosion-resistant. Suitable for portable systems, transport equipment, or applications with weight limitations.

Some manufacturers also apply powder coating or paint finishes to improve corrosion protection and aesthetics, especially in exposed environments.

3. Other components

Depending on the mount design and application, bell mounts may include:

• Internal washers or bushings for load distribution

• Threaded inserts or bolts for direct mounting

• Labeling or color-coded rubber for identification and load rating

These additional components are typically made of zinc-plated steel, stainless steel, or engineered plastics, depending on requirements.

In summary, bell mounts are built from a combination of high-performance rubber and protective metal housing materials. The choice of rubber and metal depends on the application’s specific needs, including load, vibration frequency, temperature, and environmental exposure.

One of the key advantages of bell mounts is their low-maintenance design. Unlike complex isolation systems such as air springs or hydraulic mounts, bell mounts are passive components with no moving parts or pressure systems that require regular servicing. However, while they are largely maintenance-free, there are a few essential checks that help ensure long-term performance.

1. Routine visual inspection

It’s recommended to perform a simple visual check of the bell mounts during scheduled equipment maintenance—typically once or twice per year. Look for:

• Cracks or deformation in the rubber

• Signs of aging, such as hardening or discoloration

• Corrosion or damage on the metal housing

• Loose or missing bolts

Early detection of wear can prevent larger mechanical issues and ensure continuous vibration control.

2. Rubber aging over time

Although high-quality rubber compounds like neoprene and EPDM are engineered to resist environmental degradation, all rubber materials gradually age due to:

• Heat exposure

• Ozone and UV light

• Oil or chemical contact

Over several years of operation, the rubber may lose elasticity, reducing its effectiveness. In such cases, replacement is usually recommended every 5–8 years, depending on the operating environment.

3. Environmental considerations

Bell mounts used in outdoor, marine, or chemical-heavy environments should be checked more frequently. Stainless steel housings and chemically resistant rubber can extend lifespan, but regular inspection helps mitigate unforeseen failures caused by harsh conditions.

4. Tightness check

Vibration over time may cause mounting bolts to loosen. As part of routine maintenance, ensure that the bell mount bolts remain properly torqued to prevent shifting or misalignment.

5. No lubrication or calibration needed

Unlike spring isolators or dynamic vibration control systems, bell mounts do not require lubrication, recalibration, or adjustment, making them an attractive choice for applications where maintenance access is difficult or costly.

In conclusion, while bell mounts are essentially maintenance-free, periodic visual inspections and environmental awareness can greatly extend their service life and reliability. Their robust construction makes them ideal for long-term use in both industrial and HVAC systems.

Yes, bell mounts can be effectively used in marine and outdoor environments, provided they are made with the right combination of materials and protective finishes. Their ability to isolate vibration and absorb shock makes them especially valuable in challenging conditions like those found on ships, docks, HVAC rooftops, and outdoor generators.

1. Material selection is critical

In outdoor or marine use, bell mounts are exposed to moisture, salt air, UV radiation, and temperature changes. To withstand these conditions, manufacturers typically use:

• Stainless steel housings (304 or 316 grade): Highly resistant to rust and corrosion, even in salty or humid environments.

• Neoprene or EPDM rubber: These rubber types offer excellent resistance to ozone, salt spray, water, and temperature extremes.

When both the metal and rubber components are marine-grade, the bell mount can function reliably for years in exposed conditions.

2. Common marine applications

Bell mounts are often found in:

• Marine engine mounts

• Onboard HVAC units or compressors

• Pumps and control panels in ships or offshore platforms

• Dockside generators or utility units

Their compact shape and multi-axis vibration isolation are well-suited for use on vessels where space is limited and vibration sources are intense.

3. Outdoor equipment uses

Bell mounts also perform well in:

• Rooftop air handling units (AHUs)

• Wall-mounted condensers or compressors

• Outdoor backup generator sets

• Solar inverter enclosures

They help reduce noise transmission and vibration transfer to walls or rooftop structures, improving comfort and protecting sensitive equipment.

4. Protective coatings and installation practices

For added durability, some bell mounts feature:

• Powder-coated housings for extra corrosion resistance

• Drain holes or slotted bases to prevent water accumulation

• UV-stabilized rubber compounds to reduce cracking under sun exposure

Proper mounting, sealing, and occasional inspection will further improve long-term performance in outdoor environments.

In summary, bell mounts are fully capable of withstanding marine and outdoor conditions—as long as the correct materials and finishes are selected. Their rugged, sealed construction and vibration-damping efficiency make them an ideal choice for harsh environmental applications.

Proper installation of bell mounts is essential to ensure optimal vibration isolation and long-term durability. Although bell mounts are designed for ease of installation, following best practices helps maximize their effectiveness and prevent premature failure.

1. Choose the correct mount type

Before installation, verify that the selected bell mount:

• Matches the weight and center of gravity of the equipment

• Is rated for the expected vibration frequency

• Has the appropriate rubber hardness (Shore A) for the load
  Also, check whether the mount is designed for vertical, horizontal, or multi-directional isolation.

2. Ensure even load distribution

Distribute the weight of the equipment equally across all bell mounts. For example, if the machine weighs 400 kg and uses four mounts, each mount should be rated for at least 100 kg, with an additional 10–20% safety margin.

Avoid overloading one side, as this can reduce isolation performance and lead to mount damage.

3. Mounting surface preparation

Ensure that both the equipment base and the floor or support structure are:

• Flat, clean, and level

• Free from oil, rust, or debris

• Structurally sound to support dynamic loads

This helps ensure full contact and prevents slippage or misalignment.

4. Bolt tightening and alignment

• Insert the bell mounts into pre-drilled holes using bolts or threaded studs

• Tighten bolts evenly and gradually, using a crisscross pattern if necessary

• Avoid over-tightening, which can compress the rubber excessively and reduce damping efficiency

• Use lock washers or thread-locking compounds to prevent bolt loosening due to vibration

Some bell mounts include a top cover or washer that must sit snugly against the base plate for optimal performance.

5. Check for thermal and vibration expansion space

Allow a small clearance around the mounted equipment to account for:

• Rubber compression and rebound movement

• Thermal expansion or contraction of metal parts

This prevents parts from rubbing against surrounding structures, which can create noise or wear.

6. Post-installation inspection

After installation:

• Verify that the equipment is level

• Confirm that all mounts are carrying weight evenly

• Check for any unusual noises or vibrations during initial operation

Periodic rechecks after the first few days of use help catch any early issues such as bolt loosening.

In conclusion, installing bell mounts correctly involves selecting the right type, distributing the load evenly, preparing the surfaces, and tightening components with care. These simple steps ensure reliable vibration isolation and extend the lifespan of both the mounts and the supported equipment.