Page 20 - 2019 Product Technical Manual - Hydraulics
P. 20

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M D G 41

MDG 41 is a document which was created in response to an increasing number of incidents involving high-pressure fluid
injection injuries on mine sites. In response to this, the Nsw Department of Primary Industries (DPI) established ajoint
committee with involvement from the Mining industry, Equipment Manufacturers, Repairers, and suppliers ofF|uid Power
components in order to formulate a ’best practice’ document. The result is Mechanical Design Guideline Number 41 (MDG 41).
The Mechanical Design Guidelines are a series of tools to assist companies in achieving compliance with the OH&S Act and
Regulations through implementing industry best practices. We all have a duty of care to assess the hazards in the workplace
and to implement systems and programs in order to eliminate or minimise the riskthey present.

These documents prompt the review ofmany areas in fluid power systemsthat may presenta riskand sets outguidelines of
how they should be addressed using ‘best industry practice’.

RVCO have a commitment to OH&S and the MDG's, and as such have developed products and strategies to assist our
customers in understanding the requirements ofthe guideline. we can assist you to adopt the recommended practices
outlined in MDG 4’l and MDG15.

M DG 1 5

MDG 15 is a guideline for all mobile or transportable plant used at mines, and refers to MDG 41 for fluid power systems.

It has further requirements in relation to the routing of hosing.

Where the hose and fittings tinsertllerrule) are from the same manufacturer and are assembled and crimped using
the method as specified by that manufacturer.


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 91' could produce parts on the lower limits
ofthe tolerance, and manufacturer '5' ison the upper end ofthe tolerance. lfa fitting from '5' was put on a hose from ’A’ at
the specified crimp diameter of '5', there would be little chance ofadeq uate 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 orthe hose reinforcement could be cut. again resulting in premature failure.

MDG 4i stipulates hose assemblies shall only be carried out using “Matched Hose and Fittings” (MDG 41 Clause kl.
MDG 4’l defines a “Matched System" as "where the hose and fittings (insert/ferrule) are from the same manufacturer and are
assembled and crimped using the method as specified by that manufacturer" (MDG 41 clause 1.5.1 3)\

suppliers ofmanufactured 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
fittingstogether to ensure optimum performance and reliability. All this is achieved using RVCO’s assembly methods which
are reliable and easy to follow.


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