Grover Permaseal® Rings

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Modern transmissions rely on specialized metallic hook rings, and Grover Corporation is a leading manufacturer of new and replacement parts. Automotive customers, makers of heavy off-road vehicles and users in the blower, agriculture and construction rings all count on Grover Transmission Rings.

Although transmission applications require several types of rings, Grover's metallic hook type rings are most frequently found in hydraulic transmissions, hydraulic clutches, torque converters and hydrostatic transmissions. Ideal for installations that require restricting the ring, such as; counter boxes, blind assemblies, or when passing ring grooves.

Some of the specific benefits of Grover's metallic hook rings are:

  • Manufactured of piston ring grade cast iron and other materials for performance designed for your particular application
  • Standard hook rings conform to the material specification of SAE J1236
  • Bronze alloys and high strength iron are available for customized application needs
  • Grover hook rings provide ease of assembly, excellent sealing performance, and long service life.

We understand that your company and your needs are unique. So are our products and services. From rings of 7/8 of an inch (22.23mm) in diameter to over 36 1/2 inches (927.1mm), Grover Corporation will produce any ring for any application to meet your unique requirements.

As a Grover customer, you will not have any surprises. We deliver rings on-time, as specified, and packaged the way you need them. We have the ability to manufacture economically and distribute a wider variety of sizes in both low and high volume. Moreover, standard as well as non-standard ring joint dimensions are provided to meet your specific application requirements. Because every customer has different application needs, Grover provides the value-added service of customized programs uniquely suited to specific piston ring needs.

Product News

Grover Permaseal®

High-pressure sealing applications pose specialized technical challenges. Grover's exclusive Permaseal® joint design has become the industry standard for hydraulic cylinder service. Because the Permaseal® joint design is bi-directional, fewer rings are required in double-acting applications and eliminate costly assembly errors in all hydraulic applications.

Permaseal® outperforms all other piston rings when passing open ports. It's unique overlapping, interlocking joint design prevents the ends of the ring from moving radially outward when passing open ports, and eliminates the danger of port-clipping. Port diameters up to four times the ring width have been accommodated.

Grover has prepared a Technical Bulletin that allows engineers to take full advantage of Permaseal® rings in the following applications:

The Tech Bulletin includes full details on available sizes, materials, and coatings:

Sizes: Available sizes range from 1 1/2 inch (38.1mm) in diameter all the way to 90 inches (2,286mm).

Material: Cast iron is typically used to manufacture piston rings. The material is specially alloyed to provide the best combination of wear characteristics, temperature stability and impact strength for new hydraulic and pneumatic applications. Grover can also provide many alternate materials that can be machined to solve unique or more difficult sealing applications.

Coating: Most Permaseal® rings have a manganese phosphate coating. This surface treatment is best suited for cast iron and ductile iron rings where break-in lubricity and rest prevention is critical. Our manganese phosphate meets the AMS 2481F and MIL-P-16232E mill standard. Other coatings include flash or hard chrome, tin and tin/nickel, electroless PTFE/nickel and silver lead indium.

Design Issues: The Tech Bulletin explains how the unique overlapping design of the Permaseal® ring allows end clearance to compensate for cylinder diameter tolerance and thermal expansion. It also eliminates the need for ring fitting during assembly and allows for ring and cylinder wear during operation.

The Tech Bulletin is available on the Grover Website, or by contacting your Grover Customer Service Representative.