The History of Vee Packing in Fluid Power Systems
Early Fluid Power systems from the late 1600’s through the first part of the 20th century were focused heavily on Steam Power. Fluid Power Seal technology at that time was literally using ham hock rinds compressed into the required sealing area. This became known as “packing” and the name is still used commonly to this day. “Washers” were cut to fit the piston rod, essentially packing the space where it entered the cylinder in an area referred to as the “stuffing box”. Continual pressure on the washers was implemented through means of a bolted flange and tapered face follower which in turn caused the washers to press on the rod, establishing a seal.
In 1928, Garlock Palmyra invented Vee Packing and coined the phrase “Chevron” Vee Packing. Vee Packing would become a tried and true seal of modern fluid power for the next several decades. Palmyra’s Vees were made of Duck and Rubber tubing. This packing worked so well, that it revolutionized the fluid power industry and became the prevalent packing in industrial hydraulic and pneumatic systems for the next several decades and still is used today by some OEM’s.
There were certainly many manufacturers of Vee Packing over the years which caused a variety of names for Duck and Rubber Vee Packing. In the fluid power business, Vee Packing is often referred to by many names such as V-rings, Chevron® Vee Packing or Chevron® stack sets. The fact is Vee Packing is a fantastic, (and at the time, revolutionary), style of seal. It is comprised of a set of multiple highly adaptive lip seals, including a male and female adapter on the top and bottom, for use in sealing the rods and pistons. The Vees are tapered to snap into the housing during installation to provide a quick and effective seal. They are available in a multitude of fabrics, rubbers and a wide assortment of other compounds such as Duck & Rubber, Neoprene®, Viton® & more to contend with key factors such as temperature and fluid compatibility.
Is Vee Packing a Quality Seal Compared to Modern Day Seals?
The US Military believes so! Vee Packing is still relied on by the US Military to seal a variety of its critical fluid power systems. It is no secret that US Military weapons systems contain some of the most advanced technology in the world. Consider the fact that many of these systems still utilize a 90 year old seal design that was the retrofit to pork rinds. If that is not a testament to quality and relentless reliability I don’t know what is.
In the commercial fluid power industry we still see OEM’s utilizing Vee Packing. Perhaps it is reliability that is the reason why telescopic cylinder manufacturers like Custom Hoist®, & Hyco® have relied on Vee Packing for years. These cylinders often are used in life-critical applications, where failure could be catastrophic, yet Vee Packing is still in many of their cylinders today.
Why is Vee Packing Pro-Duck-ion Declining Throughout the Industry?
So why are we experiencing a decline in Vee Packing throughout the fluid power industry? There is no doubt that modern materials and technology have advanced the sealing products produced by large seal manufactures Parker Seal, Hallite and Trelleborg. If you look at the advantages of the design of Vee Packing compared to modern day urethane U-Cup seals that often replace Vee Packing, they have nothing to do with quality. The driving force seems to be cost.
In actuality, a urethane U-Cup seal, which in itself is generally considered a good seal for typical fluid power applications, is also much less expensive than the multi-lip seal system of Vee Packing. It appears that the Vee Packing’s advantages over a U-Cup style urethane seal are being overshadowed by a demand to reduce cost. The truth is that the manufacturing process required to produce Duck and Rubber Vee Packing has not really changed significantly over the years. The Duck and Rubber Vee simply requires a much more labor intensive process of compression molding compared to urethane products which can be injection molded and greatly reduces labor cost.
As Fluid Power OEMs design systems with the focus of increasing their competitiveness they most certainly focus on reducing cost. The cost of a set of Vee Packing that may contain at minimum 5 components, compared to that of a single-lip urethane U-Cup seal is certainly higher.
The Impact to Fluid Power Systems Containing Vee Packing
As a result, Vee Packing is no longer the dominant sealing system in the industry. Complicating the issue is that often the machined tooling used to manufacture Vee Packing by major manufacturers is nearing the end of its life and would require a capital investment in machined tooling for a product that is being phased out by new business. In many cases large manufacturers are simply discarding these types of seal molds due to lack of demand. The large manufacturers of this once heavily used packing are focused on the sealing systems of the future. Their business plans are focused on earning future business of OEMs; building the cylinders of tomorrow. These systems will use a more economical sealing system. The spare part business for small orders of seals is simply not what these large manufacturers are looking for.
The obsolescence of Vee Packing should be a concern for the millions of companies that still rely on hydraulic and pneumatic systems with Vee Packing. These systems perform work that produces profit. In the event those sealing systems experience failure, many will require access to quality Duck and Rubber Vee Packing that can ship the same-day or face a line-down situation. With the correct Vee Packing set and proper maintenance, these systems can produce profit for a plethora of organizations for decades and avoid the need to procure new equipment. Organizations that have equipment with Vee Packing should be especially mindful of their inventory of seals. The industry decline has caused lead times and pricing to escalate. This can leave the customer with a perfectly good piece of equipment in an uncomfortable predicament of not being able to procure Vee Packing from the OEM of their cylinder for weeks, if at all.
Allegheny York Co. Increase Vee Packing Tooling Production to its 45 Year Inventory
Allegheny York Co has watched the decline of Vee Packing and other Duck and Rubber products like piston cups over the years. Through our years as a manufacturer and distributor of hydraulic and pneumatic seals, we have carved our niche in fluid power sealing solutions. While we represent some of the largest seal manufacturers in the world, our focus is meeting the needs of industrial customers who have emergency line-down situations and require a quality seal to fill their groove appropriately. Our business has grown considerably with this business model. Our 9 Pan Stone Compression Molding Machines are state-of-the-art compression molding equipment. Each day, our engineering department works with our machinists to produce new tooling for standard and metric size Vee Packing and other seals that OEMs are generally unable to supply quickly or affordably. Our ability to produce custom tooling quickly and affordably is much of the reason our customers rely on Allegheny York Co rather than the cylinder OEM.
Allegheny York Co is located in Manchester, PA, just 20 minutes south of Harrisburg, PA. We manufacture and stock more than 450 sizes of Duck and Rubber Vee Packing. We have one of the largest inventories in the world, including Teflon, Viton & Nitrile materials that make up over 2,800 different Vee Packing molds. Our standard Vee Packing sizes range from ½” to 22” and we carry over 70 metric sizes from 20mm x 30mm to 400mm x 440mm. For diameters in the 40”+ range, we offer a spiral Vee Packing in-stock and ready to ship. For those emergency situations we likely have what our customers need in stock. If we do not, our engineers have the capability to draft designs for molds and construct the tooling to produce Vee Packing specific to our customers’ needs within 3-5 days.
See for yourself how extensive our Vee Packing inventory really is! Visit our online catalog or request one today. Contact our friendly and knowledgeable staff if you have questions or need a set with specifications not shown. Visit AlleghenyYork.com to sign up for an internet account which will allow you to have immediate access to availability and pricing.
By Chip Konrad.
CEO – Allegheny York Co.