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Precision ring slide provides compact valve test solution

Precision ring slide provides compact valve test solution Based in Wakefield, Hedley Hydraulics started life as a system and component supplier to the UK steelwork industry and machine tool manufacturers. As the industry and technology have evolved, so too has the company and today it is a solution provider for a diverse range of sectors. Projects have included a helicopter ship simulation deck landing pad, the Gloucester swing bridge and the Royal Opera House hydraulic stage set. And in 2003, the company launched its emergency 'National Hose Doctor Service', a 24/7 emergency mobile hose workshop.

Its successful supply of several testing machines for established customers made Hedley Hydraulics the obvious choice for a new, compact system.  Its purpose is to test adjustable mobile cartridge valves that are used in tractor transmissions. The machine adjusts the valve to different settings and then performs a series of tests to ensure it meets the end user's specification.

The brief from Hedley Hydraulics' customer was for a bespoke machine to test hydraulic valves but there was a significant design consideration.  As the machine had to fit into an existing jig, the mechanism was subject to space constraints but, thanks to the expertise of HepcoMotion, this was achieved whilst maintaining test accuracy and repeatability.

With the help of technology specialist HepcoMotion, Hedley Hydraulics specified a Precision Ring Track PRT2 that rotates to adjust the pressure setting. Indeed PRT2 was central to the viability of this system and to Hedley Hydraulics ability to meet this customer's need for a compact solution. The company also ordered an LBG linear ball guide to clamp the valve into position. "The only other real alternative would have been for us to design our own mechanism and this is not our speciality," explained Hedley Hydraulics' Steve Bottomley. "The components HepcoMotion recommended have allowed us to keep the size of the machine down allowing us to fit it into the small space envelope available."

HepcoMotion is world renowned for its continuous motion know-how. Development of manufacturing techniques and investment in new production technology has led to the company's introduction of its flagship PRT2 ring slide and track system. This allows the creation of a limitless variation of open paths and closed circuits. For Hedley Hydraulics it provided a neat solution, simple circular motion control at the periphery where it is needed and a hollow centre allowing easy access to the valve.  High build quality of PRT2 ensures friction-free movement and this is enhanced by dedicated bearing design; raceway conformity and low radial clearance are optimised for continuous motion applications.  

As positioning accuracy is important in this application a rotary encoder was included to provide feedback on the angle of movement of the ring. The axial load on the ring is 100N and the rotation force required to turn the valve is 30Nm.

The HepcoMotion LBG ball guide complements system performance by providing the clamping rigidity necessary to prevent any movement of the valve during the adjustment process. Its basis is a four row angular contact ball track that has numerous benefits. These include low friction, reduced differential slip and high load carrying capacity in four directions.

Steve Bottomley concludes: "The components that HepcoMotion recommended and supplied are working well in the field and have certainly saved us substantial engineering time."
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