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DESIGN NOTES

Mary C. Gannon • Senior Editor

Block coupler makes quick work of attachment change-out Operator safety and failing hydraulic systems have led to a new decompression block coupler from Holmbury. The HDB is designed for the quick change of hydraulic attachments for skid steer, compact and backhoe loaders—as well as compact utility vehicles. The decompression feature allows the operator to alleviate trapped pressure allowing for quick and easy connection of various attachments. Holmbury will launch the coupler at ICUEE in Louisville next month. It is rated for maximum operating pressures of 350 bar and temperatures ranging from -25 to 100° C. It offers flow rates of 86 lpm at 2 bar ∆P and decompression force of 130 Nm at 275 bar trapped pressure. Traditional construction equipment attachment change-out is usually done through a standard set of flat face couplers that connect to the auxiliary hydraulics. Relieving trapped pressure on the attachment (auxiliary side) was achieved by using a connectunder-pressure coupler, such as the company’s HCP series. However, explained Matt Mulder, Holmbury president, “The challenge is how to alleviate trapped pressure on the machine side. The problem is that every skid steer loader manufacturer has a different set of steps to relieve trapped pressure on the machine side. Unless this can be achieved, it is near impossible to connect an attachment because hydraulic oil does not compress.” Holmbury developed the HDB when a major skid steer manufacturer was searching for a way to resolve a problem with its high-flow grapple attachment application. Mulder said the skid steer was using a competitor’s block coupler, which decompresses by pushing on the coupling. Due to the high-flow requirement, the rigidity of the hydraulic hose and the action of the grapple attachment, that block coupler decompression circuit was opening inadvertently, causing the hydraulic system to fail and ultimately creating an operator safety issue. With the new HDB, the decompression valve cannot be inadvertently actuated during system operation. And it only 24

FLUID POWER WORLD

FPW_DESIGN NOTES 8-15_Vs6 MG.MD.indd 24

8 • 2015

The HDB decompression block coupler from Holmbury alleviates trapped pressure, allowing for quick and easy connection of attachments on mobile machinery.

7/29/15 1:47 PM

Fluid Power World August 2015  
Fluid Power World August 2015  

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