Leak-free threadless connectors speed machine assembly - Mobile Hydraulics - Eaton Hydraulics' Snap To Connect hydraulic hose system - Brief Article

Diesel Progress North American Edition, July, 2002

Most products are developed with features to address specific operational challenges. But often during the product's lifetime, other unexpected attributes can come to the fore. A good example would he Eaton Hydraulics' STC technology.

The STC (Snap To Connect) system, originally patented by Aeroquip prior to its acquisition by Eaton, was designed to operate as a simple, leak-free connection system for hydraulic hoses used in mobile equipment. Being leak-free was a key design feature.

Now, for all of its performance capabilities, one of the most attractive aspects of the STC system today has proven to be on the installation side. Eaton said that one of its primary selling points to equipment manufacturers today has been ease of assembly and a reduction in assembly time. This has recently been further enhanced by the integration of STC connections directly into components such as steering units, valve blocks, pumps and motors, reducing assembly time and cost even further.

The STC system is a snap-in connector system that incorporates a latch ring to provide positive engagement of the mating connectors and an elastomeric seal to prevent leakage. In the years since it was originally developed, some 10 million connectors have been used in a range of equipment applications and according to Eaton, there has not been a single field failure issue reported. The STC technology has been refined over the years and among the latest enhancements is increase in pressure capacity to 6000 psi.

"The concept of the STC from the initial design phase was to design a product that allowed the OE to take more cost out of the system than they could obtain just by getting a lower price," explained Steve Hargett, senior product manager for Eaton Corp. "There are a number of ways you can take cost out and one of them is on the assembly side.

"We have had several OEMs tell us that it will take between 60 and 75 seconds to hand-tighten and then torque down a standard hydraulic connection. With the female STC port machined in, it can take as little as two to three seconds. When you're assembling in some cases as many as 5200 connections a day, each second you save is a dollar value on the machine.

"The worth to an OEM in assembly time reduction is enormous. One company told us that all they'd done is look at using STC connections on all the connections that could use the STC system -- with no other changes to the product or the assembly line -- and they could produce two more vehicles per week."

The standard STC configuration incorporates a female STC adapter, which is threaded onto a pump or valve body, with the male STC connector fitted to the hose end. But manufacturers can also specify a machined in female port, which allows even more rapid assembly In many cases, Eaton components are available with an STC port option, but the company has also begun licensing the technology to allow valve manufacturers to machine the port directly into the valve body.

"We always had the intention of doing away with the adapter," said Hargett. "That's why all of our adapter products have the male STC end on the hose and the female STC end on the threaded adapter. If a customer decides I like this, I want to take it further, we can get rid of that adapter and machine the female STC port directly into the valve body To the OEM, that ease of assembly translates into cost savings."

The simplified assembly is also an influence on the service side, Hargett noted, as the STC connections can be disassembled easily with the use of a single tool. "There are definite benefits for the guy who has to change a hose out because of abrasions or any other reason you might need to change a hose," he said. "Think of a valve block on a mini-excavator. When you open up the back, there may be 12 to 16 ports. If the center hose assembly fails, in some cases, you might have to take all of them out just to get at the one.

"With the STC system, the wrench just shoves straight into the port and disconnects the fitting. So no longer do you have to take out all the assemblies, you can just take out the one that failed."

Eaton said that it plans to expand the concept of machined-in ports to more of its hydraulic components, and will also use STC technology for other applications. "We can provide low pressure formed tubing with the male STC profile," said. Hargett, who said target applications include transmissions and air conditioning systems. "We're working right now with our high pressure forming operation to provide formed high pressure tube, in the neighborhood of 3500 psi.

"The higher pressure formed STC system could be used for work circuits, buckets, scoops, attachments and things like that. It could really take away a lot of headaches in those areas."

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