Matched Solutions

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Matched System

Today’s hydraulic systems are required to withstand tremendous pressures. This means that the attachment of a fitting to the end of a hose becomes more critical. This may be a simple operation, but it is a complex engineering solution.

International Hose standards specify a set of materials and tolerances, such as internal and external dimensions and reinforcement types and patterns. The reality is that while these standards are adhered to by all manufacturers, the tolerances themselves are so broad that if the entire allowable tolerance was used in manufacturing, users would encounter a high failure rate due to hose and fitting tolerance mismatching. High quality hose manufacturers have to adopt their own tolerance limits which are often at least half of the allowed range.

This is where “Mixing and Matching” becomes an issue: Component manufacturer ‘A’ could produce parts on the lower limits of the tolerance, and manufacturer ‘B’ is on the upper end of the tolerance. If a fitting from ‘B’ was put on a hose from ‘A’ at the specified crimp diameter of ‘B’, there would be little chance of adequate fitting retention, which would most likely result in failure. Similarly if a fitting from ‘A’ was assembled to a hose from ‘B’ the likelihood is that the inner tube of the hose would be over-compressed or the hose reinforcement could be cut, again resulting in premature failure.

MDG 41 stipulates hose assemblies should only be fabricated using “Matched Hose and Hose Fittings” (MDG 41 Clause 3.8.7.1j). MDG 41 defines a “Matched System” as “ where the hose and fittings (insert/ferrule) are designed, manufactured and routinely tested to match up to a particular manufacturer’s hose type. In this case both (hose and fitting) are assembled and crimped using the methods as specified by the designer, meet the tolerance specified by the designer and have been tested as a hose assembly, at the maximum tolerance, to the specified standards” (MDG 41 Clause 1.5.14).

Suppliers of manufactured hydraulic hose assemblies must be able to guarantee that the hose and fittings used are matched. RYCO products provide our customers with a matched system. Our design teams create and stringently test the hoses and fittings together to ensure optimum performance and reliability. All this is achieved using RYCO’s assembly methods which are reliable and easy to follow.
Matched System
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