ISO 18955:2025

Railway applications — Suspension components — Rubber diaphragms for pneumatic suspension springs ISO 18955:2025

Publication date:   Oct 24, 2025

Scope

This document specifies the characteristics for suspension diaphragms to achieve, together with applicable inspection and test methods to be carried out for verification.
An air spring system usually consists of a diaphragm (subject of this document) and additional components such as either emergency or additional springs, or both, and other assembly parts. This document does not detail the other components of air suspension or control systems such as air reservoirs, air piping, levelling system, frames, stiffeners, emergency suspension systems or elastic supports (such as series springs), etc., which will affect the diaphragm performance.
This document applies to suspension diaphragms (inflated with air) designed to be fitted on railway vehicles and similar vehicles running on dedicated tracks with permanent guide systems, whatever the type of rail and the running surface. These parts are typically made with elastomer, textile fabrics and metallic beads.