Short final-drive hubs
Compact axial envelope and controlled end-play layouts where a toric O-ring group cannot generate correct face pressure — DF marking on the worn part is the strongest cue.
Type DF · Diamond elastomer
Mechanical face seal for Komatsu-type and compact axial housings — short final drives, square-bore track rollers and controlled end-play layouts where a toric O-ring profile will not fit.
A DF floating seal is a mechanical face seal with diamond-profile elastomer loaders: two metal rings with lapped faces, each paired with a square / diamond-section elastomer ring in a seal house. The diamond ring provides static sealing, axial loading and wear compensation; the metal faces do the dynamic sealing work.
Type DF uses a diamond-profile elastomer loader instead of a circular O-ring. It is specified when axial housing depth is limited or the bore pocket is square — not because the duty is lighter than DO. HuaTong rings are cast from 15Cr3Mo high-chrome alloy, heat-treated and twin-face lapped. DF is not interchangeable with DO — different elastomer section and seal-house logic.
Use this matrix before you quote or rebuild. Similar OD can still mean the wrong face pressure if the profile is swapped.
| Factor | DO | DF (this page) | XY |
|---|---|---|---|
| Metal ring pair | Two identical symmetric rings | Two identical symmetric rings | Complementary X + Y halves (different heights) |
| Elastomer loader | Toric O-ring (one per half) | Diamond / square section (one per half) | Toric O-ring (one per half) |
| Typical OEM fit | Standard duo-cone housings (incl. Cat-type undercarriage) | Compact axial / square-bore housings | OEM matched X/Y catalog groups |
| Housing logic | O-ring rolls on ring ramps in seal house | Diamond loader seats in shallow or square pockets — do not mix with DO | X and Y halves are not mirror-identical — replace as a matched set |
| Best when | Standard crawler rebuilds, aftermarket DO marks | Limited axial depth or DF marking on worn elastomer | OEM drawing lists X/Y line (e.g. SC 0760 X + Y) |
Still unsure? Send a worn-seal photo, OEM number or housing drawing — we confirm DO / DF / XY before quoting.
Summary parameters for RFQ and engineering review. Full size charts available on request or via datasheet.
| Profile | Type DF — diamond / square-section elastomer loaded floating seal (mechanical face seal) |
|---|---|
| Set composition | Two metal seal rings + two diamond-profile elastomer rings, supplied as one matched group |
| Primary function | Retain hub lubricant; block external mud, water, sand and abrasive dust from bearing/gear cavities |
| Ring material | High-chrome alloy cast iron (15Cr3Mo family); melt, cast, heat-treat, CNC and lapped faces |
| Typical install positions | Short final drives, square-bore track rollers, carrier rollers, idlers with limited axial envelope |
| Elastomer options | NBR (general mineral oil), HNBR (heat/oil), FKM (elevated temp / chemical) — per fluid and temperature |
Housing design, installation and DF-vs-DO selection criteria. Scroll inside the panel.
| Four-step working logic | 1) Diamond elastomer compressed in seal house stores energy · 2) Rings pushed into face contact · 3) One ring rotates, faces slide · 4) Wear compensated by elastomer release |
|---|---|
| Diamond elastomer geometry | Square / diamond section grips bore pocket walls differently from a toric O-ring — controls face load in shallow or square housings |
| Seal house (floating seat) | Axial depth, pocket shape, chamfer, roughness and coaxiality control diamond-ring compression and face pressure — critical on compact hubs |
| Compact axial envelope | DF is chosen when housing depth is limited or end-play is controlled — similar OD to DO can still require DF if the pocket is square or shallow |
| Seal-house roughness (typical) | Loading surface often Ra 6.3–12.5 μm class so diamond ring can grip pocket walls without uncontrolled slip |
| Face roughness Ra | Engineering target approx. 0.05–0.20 μm after lapping; confirm per drawing and size |
| Face flatness | Often controlled to approx. 0.3–1.0 μm or by light-band inspection on critical sizes |
| Ring hardness | Common HRC 58–68; high-wear 15Cr3Mo routes may reach HRC 60–72 — always state material + test position |
| Typical duty limits | Reference class up to approx. 3 m/s line speed and 0.3 MPa face-pressure band — confirm per catalog line and housing |
| DO vs DF warning | DO must not be installed in DF seal houses (or vice versa). Similar OD can fit but face pressure becomes uncontrolled |
| Install note | Press evenly on metal ring O.D.; avoid loading the diamond elastomer directly. Verify square-bore pocket shape and axial gap before fitting new group |
| Rebuild rule | Replace both metal rings and both diamond elastomers together; inspect worn seal house before fitting new group |
| RFQ checklist | DF mark or OEM no., machine model, install position, OD/ID/height, axial gap, pocket sketch or photo, fluid, failure mode |
DF is selected because the OEM seal house and elastomer section are DF, not because the machine works in a cleaner environment than DO applications.
Compact axial envelope and controlled end-play layouts where a toric O-ring group cannot generate correct face pressure — DF marking on the worn part is the strongest cue.
Limited-depth pockets and square bore geometry common on Komatsu-type rollers and compact carrier positions — diamond elastomer seats where O-rings roll poorly.
OEM structures that specify diamond-profile loaders on excavators, dozers and loaders in the same mud and dust duty as DO — packaging fit drives the series choice.
Incomplete RFQs slow matching. Include any three of the items below and we reply within 24 hours on working days.
Short answers buyers ask before sampling or rebuilding.
No. Similar outer diameter can still produce uncontrolled face pressure. Confirm DF from the worn diamond elastomer shape, OEM mark or housing drawing before ordering.
Look at the elastomer cross-section: DF uses a diamond or square profile, not a toric O-ring. Send a photo of the cut section or the OEM part number for confirmation.
Replace both metal rings and both diamond elastomers as one matched group. Inspect the seal house for pocket wear or damage before fitting the new set.
Yes — download the DF datasheet for the summary range, or send OEM numbers / dimensions for a confirmed match and packing quote.
Send your housing drawing or worn-seal photo — we confirm profile, axial gap and elastomer compound.
