Clause 188.8.131.52.1 a) of ISO 4413:2010 “Hydraulic fluid power – General rules and safety requirements for systems and their components” states: “hose assemblies shall be constructed from hoses that have not been previously used in operation as part of another hose assembly…”
This means squeezing a new end onto a hydraulic hose that has previously been in service contravenes ISO 4413. In the majority of cases, the practical implications of this directive are not burdensome. After all, in most situations, the hose end outlasts the hose itself.
But one situation where this directive can be a ‘fly in the ointment’ for some hydraulics users is in the case of umbilical length hoses.… continue reading »
One of our members wrote me about a case study he read in which the life of a mineral hydraulic oil in a mobile hydraulic machine was extended from the 4,000 hours recommended by the machine’s manufacturer to 17,000 hours. The question raised was: “is this really possible?”
The first thing to keep in mind is that hydraulic oil should only be changed when either the base oil has become degraded or its additives have become depleted. Which means it should NOT be changed on an arbitrary number of hours in service. So in this respect, the 4,000 hour change interval recommended by the manufacturer doesn’t mean a great deal.… continue reading »
Hydraulic filter elements divide into two main categories: surface and depth. Surface filters typically have a wire mesh construction like, for example, a suction strainer. Depth filters are constructed from a matrix of fibres. Cellulose (paper), plastic, glass and metal can all be used to construct a depth filter.
Man-made glass fibers are smaller and more uniform than naturally occurring cellulose fibers. When glass fibers are woven into a layer, the result is a more consistent pore structure which captures and retains dirt better (high filtration efficiency). Plus glass’s smaller fiber diameter means there’s more of them in a given volume and therefore more spaces to catch and retain dirt.… continue reading »