Quick-acting couplings have become an important component in making mobile hydraulic equipment more versatile by allowing operators to switch from one work attachment to another quickly and easily. For example, the operator of a skid-steer loader can quickly change out a scoop shovel for a pair of lift forks — often without having to leave the cab. The operator of a loader backhoe can swap a concrete breaker for an excavator bucket — again, quickly and easily.

Quick-connect couplings designed for big machines, Fig. 2But it isn’t so easy to disconnect and reconnect a quick acting coupling on larger machines. For example, large excavators — those rated 20 tons and greater — generally have hydraulic lines sized up to1¼ in. Due to the forces required to connect or separate couplings halves of this size, an operator won’t be able push the male coupling half into the female — unless he’s King Kong. For these applications, Holmbury, Eastlake, Ohio, USA offers its PS Series heavy-duty screw couplings. Matt Mulder, of Holmbury USA, revealed, “The couplings were designed for demolition excavators and large excavators over 20 tons, where they can be used as replacements for valves when changing attachments or arm extenders.”

Quick-connect couplings designed for big machines, Fig. 1As with other quick-acting couplings used widely used in hydraulics, the PS series provides a double-shutoff action to minimize fluid spillage when connecting or disconnecting. The difference comes in the locking mechanism. Instead of just pushing the two halves together, the operator screws them together. Granted, this takes more time than just snapping the two halves together, but it’s a lot faster than the alternative — using hard-plumbed connections. Moreover, the PS series can be connected or disconnected on hydraulic lines with fluid pressurized to 50 bar (725 psi).

Another difference with the PS Series is construction. Because hydraulic systems in large excavators are frequently exposed to heavy shock and vibration, the PS Series was designed and constructed to withstand extreme vibration and pressure pulses. Independent laboratory tests have shown that the couplings withstood more than 3,000,000 pressure pulses while also being subjected to vibration in horizontal and vertical directions.

The couplings have a Zn-Ni plated carbon steel body with Viton and Viton and HBNR seals. Their internal design allows flows to 576 lpm (152 gpm) with a pressure drop of 5 bar (72.5 psi).

For more information, call Holmbury USA at (866) 465-6287.

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