Style-AC wipers are intended for use in extreme environments where wear or degradation of the wipers performance is inevitable within a short period of time. Examples of where this might occur include in the unavoidable presence of significant side-load or shock load, or on rods in poor condition. In such cases, the rod wiper can be completely removed and replaced using the Style-AC two-piece scraper, without removing the clevis. This assumes access to the wiper in the gland, either as held in place by a retaining ring in the gland aperture, or using a standard adapter or even a two-piece modified (Style-ADC) adapter. ADC adapters are similarly fully broken into two halves to permit retrofit onto a cylinder without having to pass the wiper or adapter over the rod end or clevis.  Thus a two-piece wiper and adapter can be installed on an in-service cylinder with only a few minutes work and minimal expense. Style-AC Wipers have the same dimensional specifications as standard AN (Style-A1,2 &3) wipers and are intended for use with standard AN grooves, keepers and adapters. An installation tool is available to ease installation of the proprietary spring which wraps around the wiper within a retaining groove, and is tensioned into a notch on the wiper face.

Style-AO wipers are intended for use in the presence of very fine dust particles that could potentially bypass the OD of the wiper, around the clearance between the gland and the wiper. The OD of the wiper is sealed against the counter bore of the gland groove, using an NBR or similar o-ring, installed in a secondary groove on the wiper. A low-profile spring is installed in a deep groove on the OD of the wiper, allowing for approximately 75% of the usual preload to be maintained.

The balance of the necessary pre-load is provided by a small (approx. 0.020") interference between the o-ring and gland groove. This also ensures a particle-tight seal against the groove.  Style-AO wipers have the same dimensional specifications as standard AN (Style-A1,2 &3) wipers and are intended for use with standard AN grooves, keepers and adapters. No special installation tools or procedures are required.

Thick (AT style) wipers are 'scaled-up' AN wipers for large diameter cylinders. A thicker cross section provides strength and durability, with an AT style wiper having approximately the same height (H) and cross-section dimensions proportionately, as a standard profile wiper in the mid-40's range (at approx. 5" dia.) Thus the performance characteristics of an AT-Style wiper on a large rod are at least equivalent to those of of an AN-Style on a smaller rod, and despite the extra thickness of the cross section, the elasticity and scraping potential remain approximately constant.

MS28776 Metal Rod wipers have been manufactured by many companies, over many decades, with some manufacturers making parts with small design variations. The specification defines two variants - a single piece construction and multi-piece construction, but allows freedom in the design of the multiple pieces that make up the wiper.  Customers have become used to a particular style of multi-piece construction, or a particular material choice. Hydrowype accommodate several different styles and try to be as specific as possible in describing what we will supply, to be sure our customers understand what they will receive. We are a qualified supplier of these parts (QPL-5049). All our MS28776 parts, both M2 and R2 are fully conformant to the spec and are manufactured and tested according to the MIL-R-5049 procurement spec. They are marked and certified as such.  

“MS28776” is the Classification for a specific type of Rod Wiper. The “M” is one of two Types (Metal and Rubber) and the “2” is the Class. So in the current spec, the correct designation for a metal dash 17 is MS28776M2-17. Reference to an AN-6231-17 or MS28776-17 may mean that the parts was named (on a print or procurement spec) when a previous version of the spec was current. There have been four revisions of the MIL-R-5049. As far as we know, the first version and the two following revisions of MIL-R-5049 referred to only one type of wiper –MS28776 wipers, (marked with MS28776-(dash number)). The latest and last)revision, Rev D, called out two different Types – the M2 (Metal) and R2 (Rubber) – the rubber was added in Rev. D. Therefore, a print calling out AN6231-17 or MS28776-17 almost certainly refers to an all-metal wiper – which is now correctly identified as MS28776M2-17. Some defense customers insist that the old identification be used so as to be consistent with the older prints, so Gad-jets still supplies metal wipers with MS28776- marking at specific request and after provision of a letter of waiver. 

MIL-R-5049 defines a wiper profile suitable to fit a standard groove however it does not define the use of springs or other methods of achieving performance, although several tests are defined which measure the level of performance. Gad-jets offers six styles of wipers that conform to the MS28776 standards the following describe some of these: 

Style-1 (sometimes referred to on prints/specs as AN6231 or MS28776): This is a scraper ring only - there is no spring. The Style-1 is available for all of our standard imperial and metric dimension rings. It is most frequently used in the smaller diameters. It is the longest-serving of the designs and conforms to the MS28776 specification. 

Style-3 (MS28776M2): Available in standard imperial dimensions ranging from Rod-size of 1/2" to 1-3/8". Also select metric dimensions (including the 10mm and 12mm).This has two flat "c" springs preloaded in our plant. It is not easy to remove these springs. 

Style-2 (MS28776M2): Available in standard imperial dimensions ranging from Rod-sizes of 1-7/16" to 13" (also larger). This has a single proprietary "serpentine" spring preloaded in our plant. But the spring can easily be removed to aid in installation.

If the desired style is known then we can provide a detailed sketch and model for future reference. As a general rule, given that the earlier revisions of the specification (those mentioning “AN” for instance) had fewer qualification requirements, they often are taken as referring to Style I which is the simplest design, but also the least performant. However this is not an absolute rule and as far as we can tell, there were significant variances in the design of each vendor's versions from the very earliest version of MIL-R-5049. To be safe, for the version that meets all of the requirements of the current revision of MIL-R-5049, we recommend Style III.