Parker Hannifin announces a new range of stapleless and threadless couplers designed to address the limitations of staple couplers or threaded couplers in Longwall applications.
The use of staple couplers resulting in an alarming number of hydraulic hose failures prompted Parker to develop a new stapleless coupler that will revolutionise high pressure fluid control in Longwall mining.
Due largely to the limited annular engagement of staple fittings, the staples are vulnerable to fatigue, failure and ‘walk-out’ as well as corrosion, abrasive wear and even shape deformation resulting from their first insertion into a connector fitting.
Various thread-retained locking mechanism couplers designed to address these problems also have several disadvantages, including the need for special tools to assemble and disassemble, and compromising the relative rotation of the coupler. The typical Longwall environment also produces a lot of fine coal dust, mud and water, which can easily corrode and clog threaded couplers or cause them to jam prematurely.
The new Parker HPK stapleless coupler addresses these fundamental flaws in the design of the staple-type coupler as well as the practical problems associated with other threaded couplers and associated corrosion.
Featuring an innovative design that has no threads to jam, wear or fail, requires no assembly tools, is quick and easy to connect and release, and has only two working parts, Parker’s HPK stapleless couplers are designed to solve all connection problems associated with moving high pressure fluids from pump station via monorail to roof supports at the face of the Longwall, according to Parker Mining Market Manager, Gary Nauer.
The HPK Stapleless Coupler Design
The end of each hose to be connected is crimp-fitted with a matching Parker hose shell featuring a long nipple that slides snugly into a central stainless steel bushing. The new hose coupler, which opens and closes with a simple clam shell action, consists of two halves made from high strength steel with a robust hinge that doubles as a spring clip to secure the two halves when closed. This clam shell utilises a circular lock into a deep recess at each end of the hose nipple when closed and pressurised. The circular lock design ensures that more than 98 per cent of its surface is retained by the connector body, compared to an annular engagement of less than 12 per cent for the staple coupler, resulting in a quantum leap in connector strength and reliability. As there is no thread on the nipple or hose shell, all stress concentrators are avoided and relative rotation can be achieved in the absence of locking threads to bind the coupler.
As soon as the hose assembly is pressurised, all forces are transferred through the connector body. When the hose assembly is under pressure it is not possible to disconnect, as powerful axial forces acting on the nipples push the two hose assemblies apart. This axial force can only be overcome by shutting down the line pressure.
Disassembly is as simple as using a screwdriver to flick open the clam shell’s securing spring clip and reversing the assembly procedure.
Major benefits of Parker’s HPK stapleless couplers include less wear and tear on components, fewer part ‘change outs’ needed, faster assembly/disassembly of hoses, less operator fatigue due to easy handling, and elimination of potential hose twisting resulting in longer hose life.
Parker Mining Market Manager, Gary Nauer commented that Parker went to great lengths to ensure the design was not only simple but also extremely durable. It has passed more than 1,000,000 impulse test cycles at 560 bar without failure and the special high grade stainless steel used in its construction will ensure easy operation and a long and trouble-free service life.