Why is an oversized isolator a problem?

Deflection, not rating, produces isolation. A mount rated for 800 lb and carrying 200 lb deflects a quarter of its travel, which roughly doubles the natural frequency and can turn isolation into amplification. The load check passes either way.

Why publish nothing when the mounts are overloaded?

Past its rating a mount is outside the linear range and often bottomed out, at which point it is not a spring at all. An extrapolated deflection would be a guess dressed as a measurement.

Should I add more mounts to be safe?

Not for isolation. More mounts share the same weight, so each deflects less, the natural frequency rises and isolation gets worse. They help stability and load distribution; if you add them, soften them proportionally.

Springs or elastomeric mounts?

Deflection decides it. Elastomer pads run a tenth to half an inch, giving 5 to 10 Hz natural frequencies, fine above about 1200 rpm. Steel springs run one to three inches and 2 to 3 Hz, which slow machinery needs.

Acoustic, Noise, Vibration & NVH Products calculator

Vibration Isolator Load and Deflection Calculator

Check a set of isolators against the machine they carry. Enter the operating weight, mount count, rated load and rated deflection; the page returns load per mount, utilization, deflection and natural frequency.

What this calculator does

Check isolators against the machine: load per mount, rating used, static deflection, and the natural frequency that deflection produces.

Formula used

Load per isolator = equipment operating weight ÷ number of isolators
Rating utilization = load per isolator ÷ rated load × 100
Static deflection = rated deflection × (load per isolator ÷ rated load)
Natural frequency = 3.13 ÷ √(static deflection in inches)
Total isolator rating = rated load × number of isolators

Inputs explained

Equipment Operating Weight: Operating weight the mounts carry, including fluid, product or inertia base.
Number of Isolators: Number of mounts sharing the load. More mounts is not better.
Rated Load per Isolator: The mount's catalogue load rating, per mount.
Rated Deflection at Rated Load: Deflection at full rated load, from the catalogue.

How to use the result

Best suited to verifying a supplier's mount selection before ordering, diagnosing correctly rated mounts that still transmit, choosing four soft mounts or six stiff ones.
Does not check mount strength, temperature rating, chemical compatibility or fatigue life. Says nothing about lateral or rocking stability, which soft mounts under a tall machine can lose. Publishes nothing past the rating: a bottomed-out mount has left the regime this arithmetic describes.

Common questions

Why is an oversized isolator a problem? Deflection, not rating, produces isolation. A mount rated for 800 lb and carrying 200 lb deflects a quarter of its travel, which roughly doubles the natural frequency and can turn isolation into amplification. The load check passes either way.
Why publish nothing when the mounts are overloaded? Past its rating a mount is outside the linear range and often bottomed out, at which point it is not a spring at all. An extrapolated deflection would be a guess dressed as a measurement.
Should I add more mounts to be safe? Not for isolation. More mounts share the same weight, so each deflects less, the natural frequency rises and isolation gets worse. They help stability and load distribution; if you add them, soften them proportionally.
Springs or elastomeric mounts? Deflection decides it. Elastomer pads run a tenth to half an inch, giving 5 to 10 Hz natural frequencies, fine above about 1200 rpm. Steel springs run one to three inches and 2 to 3 Hz, which slow machinery needs.

Last reviewed 2026-10-01.