Photo courtesy of Danfoss
The Danfoss EC881 Dynamax Aeroquip Hose is a two-strand braided hose with a 35 percent higher pressure rating than other hoses of the same type.
For many years, hydraulic system pressures have increased in mobile machinery, all in the name of improved productivity.
The hydraulic pump and downstream components must provide the power the machine needs to move faster, lift heavier loads, and meet other end-user requirements. This is no different in electric machines. Buyers expect the performance of an electric machine to at least match the equivalent diesel machine.
When designing a new generation of its electric backhoe, a major US OEM specified the same high-pressure fluid transport components as the previous generation machine. The result, however, was far from the same: the result of a surprise development in the routine RFQ process.
Braided Hose Spiral Performance
High pressure applications require spiral hoses. This is common knowledge based on the fact that hose pressure ratings increase with each layer of wire added.
Spiral hoses usually have 4 or 6 layers of wire reinforcement while braided hoses only have one or two layers.
Requiring a hose capable of meeting working pressures of 3,800 psi, the backhoe OEM specified SAE 100R12 four-thread spiral hoses for the high-pressure line between the machine’s hydraulic pump and the main control valve. As per its usual process, the OEM issued an RFQ for these hoses to various suppliers. It was during the RFQ process that Danfoss Engineers identified a value engineering opportunity.
The company recently launched its Aeroquip by Danfoss EC881 Dynamax hose, a two-strand braided hose with a 35 percent higher pressure rating than other hoses of the same type. The EC881 hose is rated for 1 million impulse cycles, a rating that traditionally requires coil construction. With its higher pressure capabilities, EC881 hose can replace four-wire spiral hose in certain applications, providing direct cost savings and several design advantages.
The braided hose is much more flexible than the spiral hose, which allows the hose to be reoriented and even reduced in length, contributing to further cost savings, the manufacturer said. The braided hose is also lighter in weight than the coiled hose, which reduces the overall weight of the machine, helping to improve fuel efficiency.
The OEM RFQ called for 100R12 size 12 hoses (0.75 inch ID). The Danfoss EC881-12 hose met the working pressure, burst pressure and other specifications for the application, but at a much lower cost. Recognizing the potential, the project team suggested a deviation to the OEM’s engineering team. Deviations at the RFQ stage are relatively common. What made this situation unique was the change to a different hose construction.
“The mentality has been, if I want spiral performance, I need spiral hose. And now we’re saying there’s this braided hose that can do the same thing. They’re skeptical,” said Scott Larson, senior engineer at Danfoss Power Solutions. .
To convince the OEM, Danfoss engineers had to demonstrate the hose’s capabilities. This involved supplying large amounts of test data to demonstrate hose performance, for example how many boost cycles the EC881 hose could withstand at specific pressures.
“Once they saw the test reports and gave the story and the relationship we have [the customer]it was accepted and approved,” said Travis DeBoer, senior account manager for Danfoss Power Solutions.
A win for value engineering
Danfoss offered a quote and was eventually awarded the business. Changing from four-strand spiral hoses and fittings to two-strand braided hoses and fittings resulted in a 31 percent cost reduction for the manufacturer. Additionally, the increased flexibility of the hose will allow for easier installation on OEM assembly lines. When it comes time to change hose assemblies, end users will also benefit from the increased flexibility and lower cost of the hose.
The 100R12 hose performance specification was used to determine the hose routing on the electric backhoe, and the OEM was too far into the design phase to change that. In future generations or for other machines where space is limited, engineers can now design routing based on the greater flexibility of the EC881 hose. As a result of the backhoe project, the OEM is actively looking for other applications where it can use the EC881 hose in place of the four-thread spiral hose.
And as these successful integrations increase, Danfoss representatives anticipate that other OEMs will follow suit.
“It’s a breakthrough, in my opinion, because we’ve taken the industry standard of four-strand spiral hose, which is perceived as stronger and more durable, and come out with a product that still meets those requirements, but a lower way. hose construction cost,” DeBoer said.
For more information, visit www.danfoss.com.
