Alan Hitchcox
editor
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Hydraulic hose still looks pretty much the same as it did 50 years ago, when manufacturers adopted SAE and other standards. But standards only dictate minimum dimensional and performance characteristics. And even though some people consider hydraulic hose a commodity product, most major hose manufacturers offer products with performance that far exceeds that mandated by standards.
For example, SAE standards list a minimum bend radius for specific types and sizes of hose. Bend the hose to a smaller radius, and you’ll have to reduce the hose’s pressure rating. But manufacturers offer hose that can be bent to a much tighter radius with no degradation in rating. They also offer hoses that are almost customized to certain applications. Consider hose that meets industry standards but is substantially lighter in weight. The weight of hose may seem negligible for most applications, but it’s not unusual for over-the-road car carriers to use more than 3000 ft of hose. Lighter hose makes lighter carriers, which equates to better fuel economy.
Still, is hose a commodity product? Far from it. As evidence, look at all the design improvements and new hoses each manufacturer has introduced through the years. Each may be an evolutionary step, but today’s hose makes that of the 60s seem, well, primitive. Still, I wouldn’t be surprised if some equipment out there still has some 50-year old hose on it.
I once was fortunate enough to tour a research and development facility for hydraulic hose. The tour started in a room where different types of materials were being tested for resistance to abrasion, high temperatures, low temperatures, various chemicals, ultraviolet light, infrared light, flexing, twisting, bending, stretching, and other hostile conditions and combinations thereof. Other rooms ran similar tests for center tube materials, different reinforcement materials and patterns, and probably every aspect of hose design and construction.
The most memorable room was the hose torture chamber — my words, not the manufacturer’s. Here, different elements of hose that had survived previous tests were assembled into sections of hose. Each hose section was connected to a tube at each end and subjected to internal fluid pressure pulsations. The pulsations occurred about every second, just enough time for the hose to flex, relax, then flex again. Flex is not a strong enough word. The pressure spikes were instant, so the hose would jerk from a relaxed state to a rigid state. It looked just like when someone gets electrocuted in the movies.
At the same time, the outside of the hose was subjected to heat, saltwater spray, sandblasts, and probably every type of adverse condition imaginable. I wish everyone involved in hydraulics could see the expertise that goes into making the best hydraulic hose we’ve ever had. Perhaps hose would then receive the respect it deserves.
