Floating Rod Scrapers
Long lasting scraping performance in the presence of side-load, shock load; Even imperfect rods
A ductile metal scraper body with precision-machined scraping edge providing excellent rod contact and rod-following characteristics from the right combination of yield, hardness, wear-resistance and sacrificial material properties.
Integrated energizer that maintains clamping force over the lifetime of the scraper, delivering optimal loading to maximize scraping potential while minimizing CoF and breakout friction in low-power applications.
A-Series Style 1
Style-1, or single-piece construction metal wipers, while superseded by Styles 2 through 4, are available for maintenance/repair. But wherever possible, it is recommended that this style be substituted with a Style-2 or Style-3 which consistently meet the full MS28776-M2 requirements for rod contact (light-tightness test), rod pressure (scraping potential) and breakout friction. The inclusion of a metal spring that serves as a tensioning member, results in a controlled radial loading of the scraping lip, thus producing consistent scraping potential at low friction.
A-Series Style 2 & 3
Multi-piece construction (Style 2 and Style 3) metal wipers meet all MS28776M2 and R2 wiper conformance criteria (which supersede MS28776) I/A/W MIL-R-5049. Gadjets, Inc. (Cage 96679) is a Qualified Provider (QPL5049) for MS28776M2 wipers for rods from 1/2" through 13" diameter. All Hydrowype MS28776-M2 wipers are built, tested, packaged and shipped according to the governing MIL-R-5049. Style's 2 and 3 profiles meet all MIL-R-5049 requirements including static ice cycle test. Four styles are manufactured and are available in all defined material options: Brass, Bronze, as well as additional materials including Stainless Steel and certain grades of tool steel.
All styles are Cadmium plated with Gold chromate to QQ-P-416 and are inspected for required radial pressure, breakout friction and rod light-tightness per spec. Please note, only Style 2 & 3 wipers fully meet MIL-R-5049D and these must be bid on government procurements. Hydrowype certifies (N/C) and will arrange on-site inspection by our assigned QAR.
A-Series Rod Scraper dimensions are according to the MS28776 specification set forth under MIL-R-5049. Three separate Styles of scraper are provided: A solid scraping body only (Style-I), a scraping body with a narrow groove accommodating a serpentine form spring to generate scraping load (Style-2) or and a scraping body with a wide groove in the outside diameter accommodating two “c” style springs (resembling split washers) to generate scraping load (Style-3). The MS28776R2 Variant is available only in Style-2, and substitutes a Rubber energizing band for the serpentine spring.
A-Series FOR METRIC RODS
AN-Style wipers are available for Metric rods (AM-Style) having the same cross-section proportions as an imperial AN-Style wiper. AM-style wipers are available in Brass, Bronze, and Stainless Steel.
A-Series Style AI
Imperial-Metric Wipers combine an AN-Style standard wiper with a metric ID, allowing for use in existing standard (Imperial-inch based) gland grooves, keeper plates and adapters. This may also be convenient for OEM's and refurbishment shops who encounter only occasional metric cylinders, in minimizing the number of gland specifications required. Metric Wipers are not plated unless this is requested but are tested for breakout friction and rod light-tightness.
A-Series Style AC
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.
A-Series Style AO
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.
A-Series Style AT
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.
Why there are different Styles+
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 miltiple peices 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 Gadjets 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. Gadjets 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.
Installation ADAPTERS - RETAINING RINGS, KEEPER & FOLLOWER PLATES and Can's for Installation
A floating scraper relies upon axial and radial clearances to for freedom of motion within the gland. This means that snap-in and press-in installation are not possible without the assistance of additional adapters. An approximation of a snap-in installation can be used with an appropriate design and the use of a snap-ring. A bolt-on pair of keeper and follower plates permit a retained installation and cannisters (cans) are available to permit press-in installation.
RETAINING RINGS - for snap-in installation
To locate a snap-ring app
KEEPER & FOLLOWER PLATES - economical retention; in-built clearances
Flange-style pairs of sheet metal keeper (retainer) and follower plates are available, to permit an inexpensive means of retrofitting a scraper to the aperture of an existing gland. Intended to be bolted to the face of the gland, these pairs of profiled sheet metal plates, sandwich the metal wiper so as to permit radial and axial clearances, thus affording the wiper, six degrees of freedom in a floating installation.
INSTALLATION CASES - for press-in installation
Metal Cases (cans) encapsulate A-Series scrapers in an enclosed retainer permitting press-in installation methods. Metal cases are available to create assemblies of each of the following:
A-Series scraper with rear retaining ring.
A-Series scraper with elastomer wiper (nitrile, urethane, Hytrel, acetal or PTFE)
A-Series scraper with elastomer wiper and u-cup.
A-Series scraper with elastomer wiper and Poly-pak.
A-Series scraper with elastomer wiper and two Poly-pak's - forward facing and rear facing.
Assemblies come pre-assembled but can be disassembled for inspection
In most cases, Hydrowype A-Series parts are intended for installation in accordance with the MS33675 specifications. A copy of this can be readily accessed through the everyspec website.
This specification describes a "closed" housing with a defined throat clearance. In some cases, Gadjets will recommend a small revision to the throat diameter to improve retention of the scraper.
It is important to understand that metal rod scrapers in almost all cases must be retained and can not be snapped or pressed into a housing. Retention plates, keeper plates, snap rings and installation adapters are commonly used to retain the scraper in the housing.
Type M Metal Wipers (Conform to MS28776M2-dash)
Styles I thru IV
Style 1 - solid body
Style 2 - welded serpentine spring
Style 3 - two "C" Springs
Style 4 - welded band compressing open-ended (unwelded) serpentine spring
Type R Metal Wipers (Conform to MS28776R2-dash)
Styles 5 - 6
Style 5 - round profile nitrile oring contained within a groove by a metal retaining band.
Style 6 - rectangle profile nitrile oring contained within a groove (no metal retaining band)
Rod Compatibility & Testing for A-Series Scrapers
The following are general guidelines and are not intended to supersede information gathered from application and equipment specific testing.
Gadjets recommends testing of all exclusion seals, in the actual environment, on the actual equipment, prior to placing into service. The performance of a rod scraper or metal wiper depends very much upon present environmental factors, the method of installation and retention including considerations such as the clearances provided, especially to protect against bearing of sideload and shock loads, the presence or absence of a cohesive oil film on the surface of the rod/sleeve, as well as the condition and functioning of any adjacent seals. It depends on the condition of the rod, the nature and type of contaminants and other environmental factors such as temperature, pressure, moisture and atmosphere.
Some general recommendations (for A-Series profiles) based on field observation include:
Style 3 Models
The following links provide downloadable model files in three popular formats, for Hydrowype A-Series Style 3 Scraper assemblies.
Style 2 Models
The following links provide downloadable model files in three popular formats, for Hydrowype A-Series Style 2 Scraper assemblies.