US 3891153

US 3,891,153 — "Lubricant feed means for gyratory crushers"

Scope note on the search: I searched for the literal string 3891153 / US3891153 plus litigation-oriented terms. I found no Court of Appeals for the Federal Circuit 2026 docket, ITC action, or district-court case associated with US 3,891,153. I also did not retrieve a live USPTO PatentCenter/PATENTSCOPE record through the search tool; the substantive details below come from the full patent text supplied in this session (Google Patents, https://patents.google.com/patent/US3891153/en, fetched 2026-09-29), which is the authoritative source here.

One collision to flag (do not auto-correct or conflate): a Belgian official-journal listing shows number "3891153" as a European patent validation number (31.01.2024) for an unrelated IRE1-inhibitor case assigned to Univerzita Karlova (economie.fgov.be recueil-brevets-2025-15.pdf). That is a coincidental number match in a different jurisdiction/numbering system, not US 3,891,153. Per the literal-identifier rule I report it as found and do not treat it as the same document.

Bibliographic data

Abstract (as issued)

A gyratory crusher has a wobbling crusher cone supported by a dish-shaped sliding bearing on the upper end of an axially slidable piston arranged in a stationary tubular shaft, the lower end of the piston forming a pressure-medium chamber for piston adjustment. A lubricating channel runs centrally along the axis of the entire piston, connected at its upper end to the center of the sliding bearing, while the lower end of the channel slidably engages a tubular pin that extends through the pressure-medium chamber and is fixedly attached to a cover plate closing the lower end of the tubular shaft. An exterior lubricant supply source connects to the lower end of the tubular pin, outside the cover plate.

Independent claim — plain-language overview

The patent has one claim, claim 1, which is the sole independent claim (no dependent claims). It recites a gyratory crusher comprising (lettering per the printed claim):

• (a) a housing with a feed opening at the top;
• (b) a crusher lining secured to the housing adjacent that top opening;
• (c) a stationary tubular support post mounted upright inside the housing with a closed bottom end;
• (d) a piston mounted in that support post for axial movement;
• (e) a rotary crusher cone mounted on the piston's upper end;
• (f) a substantially dish-shaped friction bearing between the crusher cone and the piston's upper end;
• (g) eccentric means associated with the cone and support post to impart a wobbling movement to the cone;
• (h) high-pressure fluid supply to the variable-volume chamber formed by the piston's bottom end and the post's closed bottom, to control the gap between the crusher lining and the crusher cone (i.e., hydraulic adjustment / "hydroset");
• (i) a conduit running axially through the piston from the friction bearing down to the piston's bottom end;
• (j) a tubular member fixed to the bottom closure of the support post, extending through that closure into the piston conduit, in sealed, slidable engagement with the conduit wall; and
• (k) means for supplying low-pressure lubricant to the outer end of that tubular member, and thereby to the friction bearing.

In short: the claim covers the hydraulic-adjustment gyratory crusher architecture in which the lubricant path to the cone's dish-shaped thrust bearing is a stationary tube fed from below the closed bottom of the support post, telescoping inside an axial bore through the piston — keeping the sliding seal small and independent of piston diameter, and separating the low-pressure lubricant circuit from the high-pressure adjustment chamber.

Supporting disclosure worth noting

• The specification identifies U.S. Pat. No. 3,372,881 as the prior-art crusher in which lubricant is routed through the housing into an annular chamber surrounding the piston, then into a piston lubricating channel; the stated drawbacks are large sealing surfaces, an inner diameter that scales with piston outside diameter, rapid seal wear, leakage, hard-to-replace seals, and consequent bearing damage. The stated object is a lubricant feed whose dimensions are independent of piston diameter and that can be installed without expensive work.
• Reference numerals in the disclosure: 1 top housing portion, 2 feed aperture, 3 crushing tool, 4 housing, 5 crusher cone, 6 supporting cone, 7 spherical segment, 8 supporting dish, 9 cylindrical bearing surface, 10 bevel gears, 11 eccentric sleeve, 12 tubular shaft, 13 piston (13a upper part / 13b lower part), 14 stacked annular (disc) springs as overload safety element, 15 pressure-medium chamber, 16 crusher gap, 17 central bore, 18 lubricating channel, 19 tubular pin, 20 hollow cylindrical enlargement, 21 coupling sleeve, 22 lubricant supply line, 23 nut, 24 sleeve, 25 pressure-medium pipe, 26 closure/cover plate, 27 hexagonal nut with sealing washer 27a, 28 reduced-diameter upper pin end, 29 sealing rings.
• The specification also describes alternatives: the lubricating channel may feed additional channels, e.g. to lubricate the annular-spring overload arrangement; and in a modified embodiment the tubular pin is rigidly connected to the piston and slides through a bore in the housing/cover plate, with the sealing rings in that bore so they are easily accessible.
• Citations of record: US 1,717,894 (Smith Engineering Works) and US 3,384,312 (Allis-Chalmers, "Spiderless gyratory crusher having frictionless bearings"). Noted citing documents include US 8,240,587 B2 and US 11,014,090 B2 (Sandvik) and EP 2532430 B1.

CAVEATS / uncertainty

• No litigation found. I have no authoritative evidence of any CAFC, district-court, or USPTO administrative proceeding involving US 3,891,153, including in 2026. I cannot confirm a negative; I simply found none.
• OCR artifacts in the source. The supplied full text contains garbled characters (e.g., [2 for tubular shaft 12, [3 for piston 13, 13//13b, H for eccentric sleeve 11 in places, "hearing" for "bearing"). I read those literally from the source and interpreted them only as ordinary OCR noise; the numeral-to-part mapping above reflects the underlying disclosure, not a correction of the identifier.
• Legal status shown is a Google Patents assumption ("Expired – Lifetime"; anticipated expiration 1992-06-24) and is not a legal conclusion.
• A similar-titled but distinct document, US 3,692,249, "Lubricant feed means for gyratory crushers" (Sept. 19, 1972), appears in the "Similar Documents" listing. I have not verified any family, priority, or assignment relationship between it and US 3,891,153, so I make no assertion about one.

I'll search for litigation involving US patent 3891153.

Let me run more targeted searches on litigation databases and the specific patent.

Let me check additional litigation-specific databases.

Litigation Search Results — US Patent No. 3,891,153

Conclusion: I found no litigation involving US Patent 3,891,153.

What I searched

I ran targeted queries against general web and litigation-oriented search surfaces, including:

• US3891153 patent litigation / "3891153" patent lawsuit
• "3,891,153" gyratory crusher patent infringement
• site:portal.unifiedpatents.com 3891153
• "3891153" OR "3,891,153" courtlistener complaint
• Kloeckner Humboldt Deutz patent lawsuit gyratory crusher 1970s

None of these returned any docket, complaint, CAFC opinion, PTAB proceeding, or litigation-report entry naming this patent.

What I found instead (not litigation)

• The patent itself: US 3,891,153, "Lubricant feed means for gyratory crushers," inventors Hanns Decker, Heinz Hurtmanns, Helmut Stockmann; assignee Kloeckner Humboldt Deutz AG. Application 102,446; foreign priority DE 2001073 (1970-01-12); filed 1970-12-29; granted 1975-06-24; anticipated expiration 1992-06-24; legal status "Expired – Lifetime."
• Hits on the string "3891153" were false positives — e.g., a Belgian patent-register PDF (an unrelated EP publication number 3891153), a Mexican municipal asset record (a Sony camcorder serial number), an Austrian police wanted notice (case number), and an FCC complaint number. None relate to the US patent.
• Gyratory-crusher litigation that did surface in results concerned entirely different patents (e.g., Cedarapids patents in M.D. Tenn., the '568 patent in an IPR, historical Traylor Engineering v. Worthington Pump) — none involve 3,891,153.

Why this is unsurprising

• The patent issued in 1975 and expired in 1992. Any infringement action would have had to be filed between 1975 and roughly 1992, and the term is long over.
• The unit of right is a narrow, single-claim mechanical claim (a gyratory crusher with an axial lubrication conduit and a tubular pin through the support-post closure). Its commercial lifespan and litigation exposure were limited.
• Its only recorded "prior art" relationships are citations — cited references US 1,717,894 (Rumpel, 1929) and US 3,384,312 (Patterson, 1968), and later-citing documents from Sandvik (US 2011/0006143; US 8,240,587; US 2016/0271614; US 11,014,090) and EP 2532430. Being cited by these is not litigation.

Important caveats on this "no litigation" finding

• I could not directly query the Unified Patents litigation portal, PACER, or Docket Alarm; those sources require interactive access. My negative result rests on open-web and search-engine retrieval, which is weaker evidence of a negative than a direct docket query.
• Pre-2000s district court dockets are often poorly indexed online, so a 1970s–1990s infringement suit over this patent could theoretically exist without appearing in my searches. I cannot rule that out with high confidence.
• Per your instruction, I am interpreting the number literally as US 3,891,153 and excluding look-alike numbers (e.g., US 3,891,153 vs. similarly numbered patents). If you intended a different number, please confirm and I will re-run.

Bottom line: On the evidence available to me, no known litigation involves US Patent 3,891,153. I recommend a direct PACER and Unified Patents portal query (and a Westlaw/Lexis KeyCite on the patent) to confirm this negative with higher confidence before relying on it.

Proceedings overview

Total AIA trial proceedings on file: 0. The structured PTAB proceedings block (USPTO Open Data Portal) returns no IPR, PGR, or CBM for US 3,891,153, and my web searches across PTAB E2E/PTACTS, CourtListener, and general web sources surfaced no PTAB proceeding, no Federal Circuit appeal, and no litigation asserting this patent. So the breakdown is: active — none; claims invalidated — none; claims sustained — none; settled — none; institution denied — none. The defensive posture this gives a defendant is unusual and mostly good news, but not because the patent is battle-hardened: no claim of US 3,891,153 has ever been tested in an AIA trial, and none can be meaningfully tested now, because the patent expired on 1992-06-24. With the exclusionary right gone for over three decades, the "no PTAB activity" signal here reflects a dead patent rather than a hardened one.

No proceeding to report

There is no {PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner} entry to render. I am not going to invent one to fill the template. What follows is the closest thing to a proceeding-by-proceeding analysis that the record supports, plus the collateral material a defendant needs.

Why the absence is structural, not accidental. US 3,891,153 issued 1975-06-24 from an application filed 1970-12-29 (DE priority 1970-01-12), to Kloeckner-Humboldt-Deutz AG, on a single claim to a gyratory crusher with a central lubricant conduit running axially through the adjusting piston and mating with a tubular pin fixed to the bottom closure plate of the tubular support post. The Google Patents legal-status record lists it as Expired — Lifetime, with an anticipated expiration of 1992-06-24 (i.e., 17 years from grant under the pre-URAA term). A patent that has been expired for 33 years has no damages tail worth attacking: infringement liability would be confined to acts within the six-year lookback preceding expiration, all of which is now long time-barred. Rational petitioners do not spend IPR fees on it.

Statutory limits that independently close the door. Even setting economics aside:

• PGR is unavailable under 35 U.S.C. § 321 — post-grant review requires an effective filing date on or after 2013-03-16 (AIA first-inventor-to-file). This patent's effective filing date is 1970.
• CBM is unavailable under AIA § 18 — it reached only covered business method patents, and the program sunset on 2020-09-16 in any event. A gyratory crusher lubrication system is a mechanical/industrial apparatus, not a "financial product or service," so it never qualified.
• IPR under § 311 is theoretically available against any unexpired-or-expired patent, but there is no petitioner with standing-based incentive and no live controversy to anchor one.

Strategic summary

Claim status. The patent has one claim (claim 1), in the pre-1975 single-claim format with lettered sub-paragraphs (a)–(k). It is UNTESTED — not canceled, not sustained, not narrowed by any AIA trial, ex parte reexamination, or reissue that I can find. There is no "surviving claim set" to list because nothing was ever trimmed. The complete claim as granted covers: a housing with a top feed opening (a); a crusher lining (b); a tubular support post with a closed bottom end (c); an axially movable piston (d); a rotary crusher cone on the piston's upper end (e); a dish-shaped friction bearing between cone and piston (f); eccentric wobbling means (g); high-pressure fluid means feeding the variable-size chamber between piston bottom and post closure to control gap (h); a conduit extending axially through the piston from the friction bearing to the piston's bottom end (i); a tubular member secured to the bottom closure of the support post, extending through that closure into the conduit, in sealed slidable engagement with the conduit wall (j); and low-pressure lubrication supply means to the outer end of that tubular member (k). Elements (i)–(k) are the point of novelty and the reason the specification distinguishes US 3,372,881 — which fed lubricant through a housing channel into an annular chamber surrounding the piston, requiring large, fast-wearing, hard-to-replace seals whose inner diameter scaled with piston diameter.

Estoppel landscape — § 315(e)(2) is inapplicable. Because no IPR ever resulted in a final written decision on any claim of this patent, no petitioner and no privy is estopped under § 315(e)(2). There is no estoppel shadow to navigate, and equally no FWD findings to leverage. Any invalidity ground a defendant might theoretically want to raise — including the two references the examiner cited, US 1,717,894 (Rumpel, Smith Engineering Works, 1929-06-18) and US 3,384,312 (Patterson et al., Allis-Chalmers, 1968-05-21, "Spiderless gyratory crusher having frictionless bearings") — remains untested and unblocked. For completeness, the two-art rejection combination that traditionally kills patents of this vintage would be built from those two references plus the specification's own admission regarding US 3,372,881, if anyone ever had a reason to build it.

Pattern signals — none of the usual tells. No repeat petitioner (there is no petitioner at all). No patent-owner PTAB appeal history (no FWD to appeal). No defensive aggregator such as Unified Patents appears anywhere in the chain — the Google Patents "Cited By" set for this patent shows only later third-party citations (Sandvik EP2532430B1; the Sandvik US 2011/0006143 / US 8,240,587 family; RU2206398C1; the Sandvik US 2016/0271614 / US 11,014,090 family), which are technology citations, not validity challenges. The assignee of record is Kloeckner Humboldt Deutz AG, an original German industrial assignee, with no reissue, no reexamination, and no continuation family that I can identify beyond the foreign counterparts: DE 2001073 A1 (published 1971-07-22), CA 926312 A (1973-05-15), ZA 708688 B (1972-01-26).

Two number-collision traps you must not fall into. Web searches on the bare string "389" and "US 3891153" pull back a great deal of irrelevant material, and it is worth naming so nobody imports it into a brief:

• US 8,726,389 is an entirely different patent (Roku/Universal Electronics remote-control key codes), and the IPRs on it — e.g., the AO Kaspersky Lab v. Webroot and related petitions at PTACTS — have nothing to do with this patent. In the Federal Circuit's Universal Electronics, Inc. v. Roku, Inc. opinion (No. 21-1992, 2023-08-18), every reference to "the '389 patent" means US 8,726,389, not US 3,891,153.
• EP 3891153 A1 ("Naphthalimidofurans for applications in molecular biology," Univerzita Karlova, priority CZ 2018671, 2018-12-03) shares the numeric suffix by coincidence of EP publication numbering. It is unrelated.
• Also note US 3,692,249, "Lubricant feed means for gyratory crushers" — same title, different patent — appears in the Google Patents "Similar Documents" list. If a defendant's invalidity search turns up "Lubricant feed means for gyratory crushers," confirm the number before citing it.

Recommended next steps

1. If a demand letter or complaint asserts US 3,891,153, the dispositive response is expiration, not invalidity. The patent expired 1992-06-24; the statutory damages window (35 U.S.C. § 286, six years) closed in 1998-06-24. Infringement of an expired patent cannot be enjoined, and any pre-expiration damages claim is time-barred. Say this first, in writing, and label the assertion what it is.

2. Confirm the expiration date and maintenance-fee history in the official record before you send anything. The Google Patents legal-status field is an assumption, not a legal conclusion (the page says so explicitly). Pull the fee record and the Reissue/Reexamination tabs from USPTO Patent Center (https://patentcenter.uspto.gov/) for US 10/2446 and the E2E docket for any ex parte reexamination that ODP might not surface. If for some reason the patent was extended, reissued, or had claims passed through an intervening reexamination certificate, that changes the analysis and you want to know it before you file an answer.

3. Do not build a PTAB strategy. There is no proceeding to join and no claim to cancel. Filing for an IPR on an expired patent is a waste of fees, and there is no FWD in this patent's history to link or quote. If asked for a citation to a disposition, the honest answer is that none exists — writing one down would be fabrication.

4. If you want a defensive fallback anyway, the two references cited on the face of the patent — US 1,717,894 (1929) and US 3,384,312 (1968) — plus the specification's own admission about US 3,372,881 and the very close-in-time US 3,692,249, are the natural § 102/§ 103 nuclei. Track them in your invalidity chart as a belt-and-suspenders ground rather than as the lead argument.

5. Treat the "no PTAB activity" fact as evidentiary in itself. A patent granted in 1975 with a single claim and a genuinely useful mechanical improvement (the piston-diameter-independent lubricant feed through a tubular pin in the bottom closure) never attracted a single AIA trial in more than a decade of AIA availability. That is what you would expect of a long-expired patent with no commercial assertion value — not of a hardened, well-asserted one. The right inference is "no live right," not "strong patent."

Confidence and gaps. High confidence on: zero PTAB proceedings; patent grant 1975-06-24; filing 1970-12-29; DE priority 1970-01-12; assignee Kloeckner-Humboldt-Deutz AG; single claim; cited art US 1,717,894 and US 3,384,312; anticipated expiration 1992-06-24. I do not have high confidence on the precise maintenance-fee payment history or whether any ex parte reexamination exists, since ODP's status field is a non-legal assumption and search results were dominated by unrelated patents — that is exactly why step 2 above directs you to Patent Center rather than to this memo.

US 3891153 — Ownership and Assignment Reconstruction

Patent: US 3,891,153 — "Lubricant feed means for gyratory crushers"
Application: US 102,446 · filed 1970-12-29 · granted 1975-06-24 · priority DE 2001073 (1970-01-12) · anticipated expiration 1992-06-24 · legal status Expired – Lifetime

Bottom line up front: No post-issuance assignment, security interest, merger, or change-of-name record was located for this patent in any indexed source I could reach (Google Patents legal events as fetched, and web-indexed USPTO Assignment Center content). The patent is a 1975 grant that expired in 1992 while still held by its original corporate owner. There is therefore no assignable chain to reconstruct — the absence of records is itself the finding. I could not query the Assignment Center's backend directly (the search interface and its API are not exposed to my fetch tooling), so this is a "no records found" result, not a certified "no records exist" result. Verify at https://assignmentcenter.uspto.gov/ (legacy: https://assignment.uspto.gov/patent/index.html) before relying on it.

Inventors

• The employer attribution is an inference from residence and assignee, not a documented fact: all three inventors list Cologne-area addresses (Cologne, Cologne, Wesseling — Wesseling adjoins Cologne and was a KHD plant town), and the patent issued to KHD as assignee, which under 1970-era practice normally reflects an employment/assignment obligation executed at filing. The assignment instrument itself is not in the record I could retrieve.
• Departure pattern: Not determinable. Gauging "inventors left within 12 months of filing" requires assignment instruments or SEC-grade employment data, neither of which exists for a 1970 German industrial filing. No finding either way — do not read the absence as a negative; it is simply unavailable.
• Note the sibling case in the same family is US 3,692,249, also titled "Lubricant feed means for gyratory crushers" (1972) — a related KHD filing with an overlapping disclosure. If you are mapping the portfolio, pull that patent's assignment record too; it is the more likely place to find any later transfer activity.

Original assignee

Klöckner-Humboldt-Deutz AG (rendered in the OCR'd front page as "Klocker-Humboldt-Deutz AG"), Cologne, Germany. Current-assignee field on Google Patents: Kloeckner Humboldt Deutz AG; original assignee: same.

• Line of business: A large diversified German capital-goods group. Relevant segments: diesel engines (DEUTZ), agricultural machinery (later Deutz-Fahr), commercial vehicles (Magirus-Deutz), and — most relevant here — industrial plant and mineral-processing equipment through KHD Humboldt Wedag (crushers, grinding mills, cement and ore-processing plants). The patent sits squarely in the Humboldt Wedag crushing-equipment line.
• Did it ship a product embodying the claims? Almost certainly yes, subject to the normal caveat. The specification describes a hydraulic-adjust gyratory/cone crusher of a type KHD Humboldt Wedag built and sold commercially, and the patent expressly distinguishes the prior art US 3,372,881, itself a gyratory-crusher patent — i.e., this is a production-machine improvement, not a paper patent. There is no licensing-only history attached to it.
• Current status: The original entity no longer exists under that name. Corporate history: KHD was restructured in 1986 into KHD Antriebs- und Luftfahrttechnik GmbH, KHD Agrartechnik GmbH and KHD Humboldt Wedag AG; the agricultural division was sold to the Italian SAME group (1995/96); the remaining company was renamed Deutz AG in 1996/97 (still listed, Cologne). The KHD Humboldt Wedag industrial-plant business was subsequently separated and, in the 2010s, majority control of KHD Humboldt Wedag International AG passed to Chinese interests (AVIC). (Timeline details from German corporate-history sources; the AVIC step should be independently confirmed against SEC/regulatory filings before quoting.)
• Crucially: the patent expired 1992-06-24, roughly three years before the ag-division sale and four years before the rename. Any later corporate reshuffling of KHD is therefore irrelevant to this asset — an expired patent is not normally swept into a divestiture package, and there is no evidence it was.

Assignment timeline

The USPTO Assignment Center has no post-issuance records for US 3,891,153 that I could locate. No reel/frame, no conveyance type, no assignor/assignee entry, and no correspondent of record is available. Google Patents' legal-events data as fetched shows only: application filed (1970-12-29), granted (1975-06-24), anticipated expiration (1992-06-24), status Expired – Lifetime. There is no AS | Assignment event in that feed.

Per the operating rules, I stop the chain reconstruction here. I will not manufacture reel/frame numbers.

For completeness, the only attorney/firm identifier associated with this patent is the prosecution correspondent printed on the face of the grant, not an assignment correspondent:

• Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson — attorneys of record, Chicago. This is the firm that prosecuted the application. If an original inventor→KHD assignment was recorded in 1970, this firm is the most likely recording correspondent — but no such reel/frame is retrievable, so this cannot be elevated to a finding.

Timeline diagram

timeline
    title Ownership of US 3891153
    1970 : German priority filing Jan 12
         : US application filed Dec 29
    1975 : Patent granted Jun 24
         : Owner Kloeckner Humboldt Deutz AG
    1992 : Patent expires Jun 24
         : No recorded assignment ever

NPE / troll-pattern signals

Note on a genuine near-miss worth recording: KHD's later corporate history (ag division to SAME, rename to Deutz AG, Humboldt Wedag separation, eventual AVIC control) is exactly the profile that sometimes produces a portfolio sale — a shrinking, financially stressed machinery conglomerate shedding non-core IP. But this patent expired in 1992, three to eighteen years before those events. Any portfolio fire-sale that occurred would have been confined to then-live KHD patents. Do not attribute later KHD divestitures to this patent.

Verdict

Insufficient data. No post-issuance assignment record exists for US 3,891,153 in any source I could reach, which under pre-1995 practice and a 1992-06-24 expiration means the patent was almost certainly held by Klöckner-Humboldt-Deutz AG for its entire enforceable life and simply lapsed there. There is no shell-entity transfer, no asserter in the chain, no repeat recorded correspondent, and no litigation, so no NPE signal reaches even the weak-evidence threshold — the chain is a single operating-company owner with a product line and a statutory death date, not a laundering structure. The correct characterization is operating-company ownership terminated by expiration, which is the practical equivalent of "no story here"; I select Insufficient data rather than "Operating-company assertion" only because there is no recorded assignment instrument in hand and no evidence of enforcement.

Verify the record yourself:

• USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (search Patent Number 3891153)
• Legacy Assignment Search: https://assignment.uspto.gov/patent/index.html
• Patent text / legal events (source of the data above): https://patents.google.com/patent/US3891153/en

Caveats, stated plainly: (1) I could not execute a direct query against the USPTO Assignment Center database; my searches did not surface any indexed assignment record, which is weaker than a certified negative. (2) The inventor-employer attribution and the "KHD shipped this machine" statement are reasoned inferences from the specification and corporate history, not documentary findings. (3) The 1986 restructuring, 1995 SAME sale, 1996 rename to Deutz AG and later KHD Humboldt Wedag International AG / AVIC history come from secondary German corporate-history sources and secondary press and should be confirmed against primary filings before being quoted as fact — and none of it bears on this patent, which expired in 1992.

I'll research US Patent 3891153 and its cited prior art references.

I have strong data on the primary citation. Let me verify the second cited reference.

Identification Confirmation

I searched for the specific number 3891153 (US 3,891,153 A). This is confirmed as a distinct, single record — not a variant of a similar number (e.g., not the sibling US 3,692,249 A). Key bibliographic data:

Source: https://patents.google.com/patent/US3891153/en (Google Patents mirror of the USPTO record).

Because this patent has only one claim, every § 102 analysis below must be read against that single claim (claim 1, elements a.–k.).

The Reference List as It Appears on the Face of US 3,891,153

The front page lists exactly two (2) "References Cited" — both appear to be examiner citations:

1. US 1,717,894 A — Smith Engineering Works — "Crusher"
2. US 3,384,312 A — Allis Chalmers Mfg. Co. — "Spiderless gyratory crusher having frictionless bearings"

Note on literal interpretation of identifiers: The specification's background discussion also names a third patent in the form "U.S. Pat. No. 3.372.881." Rendering that OCR literally, the identifier is 3,372,881 (Winter). I am flagging it because it is discussed in the body of the patent yet is not listed in the front-page "References Cited" table. I am not substituting or "correcting" any number; I am simply reproducing the three identifiers as they appear.

Reference 1 — US 1,717,894 A

Full citation: Smith Engineering Works, "Crusher," U.S. Patent No. 1,717,894 A.

• Filed: 1927-08-22
• Granted/Published: 1929-06-18
• Source: https://patents.google.com/patent/US1717894 (PDF: patentimages US2814450 cross-reference; Google Patents record)

Brief description: A gyratory/cone crusher in which a vertical crusher shaft 9 carries a cranked upper portion 27 on which the crushing head 28 is mounted via roller/roller-thrust bearings (29–33). Drive is through a bevel gear 22/23 and horizontal shaft 24. The relevant feature for this case is the lubrication arrangement:

"the shaft is formed with an oil bore 15 which extends lengthwise through the shaft and at its lower end is of tapered formation… to receive the upper tapered end portion 16 of a yielding tubular connection 17. [The] connection is slidably mounted in a cap member 18 connected to the lower end of the inner hub… The cap member has a threaded bore 19 for connection with a source of oil supply… The yielding connection permits vertical adjustment of the crusher shaft 9 while maintaining an oil tight joint between the connection and the shaft, and the connection is provided with piston rings 20." (US 1,717,894)

This patent was litigated (Smith Engineering Works v. Nordberg Mfg. Co., 68 F.2d 492 (7th Cir. 1934)), a case concerned with the Symons cone-crusher patents — useful for historical context but not itself a § 102 reference.

§ 102 analysis against claim 1 of US 3,891,153:

US 1,717,894 is the most on-point reference for elements (i), (j), and (k) of claim 1 — a lengthwise oil bore running through the shaft (i), a slidably-mounted, sealed (piston ring) tubular oil-feed member at the lower end (j), and an external oil-supply connection at the outer end of that member (k). The functional concept of feeding lubricant up an axial passage of a vertically adjustable crusher shaft through a sealingly slidable tubular connection is substantially disclosed.

However, it does not anticipate claim 1 as a whole, because several claimed elements are absent or structurally different:

• Claim element (c): a "tubular support post… having a closed bottom end." In US 1,717,894 the crushing shaft is a solid/cranked rotating shaft journaled in conical roller bearings within a hub — not a stationary tubular support post with a closed bottom chamber.
• Claim element (d): a piston mounted in the support post for axial movement. US 1,717,894 uses a shaft vertically adjusted in bearings, not a piston in a cylinder.
• Claim element (f): a "substantially dish-shaped friction bearing between [the] crusher cone and [the] upper end of the piston." In US 1,717,894 the head is carried on roller/antifriction bearings on the cranked shaft — not a dish-shaped (spherical segment/convex-concave) friction bearing.
• Claim element (h): means for supplying highly pressurized fluid to a variable-size chamber to control the crusher gap. US 1,717,894 has no hydraulic gap-adjustment chamber.
• Claim element (j) in its specific claimed form: the tubular member is secured to the bottom closure of the support post; here the tubular connection is mounted in a cap at the hub, but the overall hydraulic/post architecture differs.

Conclusion: US 1,717,894 is a strong § 102(b)/§ 103 reference directed at the "slidable sealed tubular lubricant feed up an axial bore" sub-combination (elements i–k), but it does not by itself anticipate the full claim 1 combination. It is best characterized as the closest single reference on the lubricant-delivery sub-combination.

Reference 2 — US 3,384,312 A

Full citation: Patterson, Warren R., et al. (Allis-Chalmers Mfg. Co.), "Spiderless gyratory crusher having frictionless bearings," U.S. Patent No. 3,384,312 A.

• Filed: 1966-07-25
• Granted/Published: 1968-05-21
• Source: https://patents.google.com/patent/[US3384312A](/patent/US3384312A)/en (PDF: patentimages US3384312.pdf)

Brief description: A hydraulically-adjusted, spiderless gyratory crusher:

• Base frame housing 10 with a cylindrical hub 12 projecting vertically (a stationary support post).
• Removable overhanging concave ring 20 (crusher lining) secured to the upper frame 17.
• Crusher mainshaft 25 whose lower end is secured to a piston 27 slidably fitted within a cylinder 28 in the lower housing.
• A "step bearing assembly 55" comprising concave pressure bearing 50 and convex pressure bearing 52 (i.e., a dish-shaped friction bearing) between the crusher head 57 and the top of the mainshaft head 26.
• Eccentric member 63 with ring gear 64 driven by pinion 76, causing the crusher head 57 and mantle 60 to gyrate.
• Hydraulic fluid pumped through inlet 30 into the lower cylinder 28 to raise the piston (hydraulic gap adjustment).
• Lubricant is supplied through bore 45 into the upper portion of cylinder 28, then through tube 44 (through the hollow mainshaft 25) to the step bearing assembly 55, then down to lubricate the frictionless roller bearings 66/71 and gearing.

§ 102 analysis against claim 1 of US 3,891,153:

US 3,384,312 is the most on-point reference for claim elements (a)–(h):

• (a) housing with top feed opening — disclosed (frame 10/17, concave ring 20).
• (b) crusher lining secured adjacent the top opening — disclosed (concave ring 20).
• (c) tubular support post stationarily mounted with closed bottom end — disclosed in substance (hub 12 + cylinder 28).
• (d) piston mounted for axial movement — disclosed (piston 27 in cylinder 28).
• (e) rotary crusher cone on the upper end of the piston — disclosed (head 57/mantle 60 atop mainshaft 25/piston 27).
• (f) dish-shaped friction bearing — disclosed (concave/convex step bearing 50/52).
• (g) eccentric means for wobbling — disclosed (eccentric 63/ring gear 64).
• (h) means for supplying highly pressurized fluid to the variable-size chamber to control gap — disclosed (inlet 30, cylinder 28).

It also discloses an axial passage (tube 44) through the hollow mainshaft carrying lubricant to the step bearing — broadly paralleling element (i).

Where it falls short (so it does not anticipate the whole claim):

• Claim element (j) requires "a tubular member secured to the bottom closure of said support post and extending through said closure into said conduit in the piston in sealed slidable engagement with the wall of said conduit." In US 3,384,312 the lubricant is delivered through bore 45 into the top of the cylinder and the internal tube 44 moves with the mainshaft — there is no tubular member fixed to the bottom closure and extending slidably into an axial conduit in the piston. The sealed-slidable "pin-through-the-cover-plate" architecture that is the heart of claim 1 is absent.
• Claim element (k) as claimed (low-pressure lubrication fed to the outer end of the tubular member at the bottom closure and carried up to the friction bearing) is likewise not disclosed in that specific routing.

Conclusion: US 3,384,312 is a broad structural reference for the overall hydraulically-adjusted spiderless gyratory crusher of claim elements (a)–(h), but it does not anticipate claim 1 because of the missing tubular-member-and-closure limitation (elements j and k). It would be the natural primary reference in a § 103 combination with US 1,717,894 (or with the '249 sibling below), since the two together supply the full claim 1 combination.

Supplementary References Not on the Front-Page Citation Table (flagged for completeness)

These are not among the two "References Cited," but they bear directly on the analysis and I identify them so the record is not read as complete on two entries alone:

1. U.S. Pat. No. 3,372,881 (Winter) — the crusher expressly identified in the background of US 3,891,153 as the known arrangement whose annular-chamber sealing the invention improves upon ("A gyratory crusher of this type is disclosed in the U.S. Pat. No. 3.372.881…"). Identifier reproduced literally as it appears; the 3,372,881 form is the standard rendering. It is a background/§ 102(a) or (b) reference, not a front-page citation.

2. U.S. Pat. No. 3,692,249 A (Decker, Hurtmanns, Stockmann — same inventors/assignee), "Lubricant feed means for gyratory crushers." Filed 1970-12-18 (Appl. No. 99,543), granted 1972-09-19, priority DE 1970-01-02. Source: https://patents.google.com/patent/[US3692249A](/patent/US3692249A). Note that this sibling application was filed before the US 3,891,153 filing date (1970-12-29) and by the same inventive entity. It discloses a different solution — lubricant fed through a lengthwise bore in the wall of the hollow cylindrical shaft, communicating with a longitudinal slot in the piston and a radial bore to an axial bore leading to the sliding bearing. This is a potential § 102(e) / double-patenting concern worth flagging given the overlap in inventors, assignee, and subject matter, even though the examiner placed it under "Similar Documents" rather than "References Cited."

3. Cited-By family (for forward-citation context only, not prior art): US 2011/0006143 A1 and US 8,240,587 B2 (Sandvik, 2009-07-07); AU 2010269205 B2 (Sandvik); US 2016/0271614 A1 and US 11,014,090 B2 (Sandvik, 2013-11-12); RU 2206398 C1 (2002-02-27). These are later documents that cite US 3,891,153 — useful for showing the patent's technological lineage but they cannot be § 102 prior art against it.

Summary Judgment

Bottom line: Neither of the two front-page citations, taken alone, anticipates the sole claim 1 of US 3,891,153 under 35 U.S.C. § 102. The claim's novelty resides in the specific combination of (i) a full-length axial lubricant conduit in the piston, joined to (j) a tubular member fixed to the bottom closure plate of the stationary support post and extending through that closure into sealed slidable engagement with the conduit, fed by (k) a low-pressure lubricant supply at the outer end of the pin. US 3,384,312 supplies the crusher architecture; US 1,717,894 supplies the slidable sealed tubular lubricant feed concept — making them an obvious § 103 pairing, but not individual § 102 anticipations.

Caveats / confidence: I grounded the descriptions in the patent texts themselves (US 3,891,153, US 1,717,894, US 3,384,312) and the Google Patents/USPTO-mirrored records; the exact § 102 category (102(a) vs 102(b) vs 102(e)) depends on the reference's publication date relative to the Jan. 12, 1970 priority date, which I have stated where known. I have not attempted to independently verify USPTO PatentCenter's live classification or any reexamination/assignment history beyond what the record shows, and I flag the 3,372,881/"3.372.881" and sibling '249 items as items I am identifying without correcting the literal identifiers.

I'll ground this analysis by verifying the prior-art references cited on the patent page and a few nearby documents.

Obviousness Analysis — US 3,891,153 A ("Lubricant feed means for gyratory crushers")

Patent under review: US 3,891,153 A, Decker / Hurtmanns / Stöckmann, assignee Kloeckner‑Humboldt‑Deutz AG. Filed 1970‑12‑29; foreign priority DE 2001073, 1970‑01‑12; granted 1975‑06‑24. One claim (claim 1), 2 figures.
Source: https://patents.google.com/patent/US3891153/en

Scope of the claim. Claim 1 is a single, all‑elements combination claim covering a hydraulic‑adjustment, spiderless‑type gyratory crusher, plus the specific lubricant route defined in elements (i)–(k): a conduit axial through the piston from the dish bearing to the piston's bottom end, a tubular member fixed to the bottom closure of the support post, passing through that closure into the piston conduit in sealed slidable engagement, and a low‑pressure lubricant supply to the outer end of that tube. The patent's own statement of novelty is exactly this: the lube seal is moved off the piston circumference onto a small tube, so the seal size is "independent of the diameter of the piston" and is easily serviced.

1. Prior art of record on the page (and why each is available)

Note on the rule against auto‑correction: the printed patent's reference list OCRs as "3.372.881" / "3.384.3[2" / "l 7l7 894"; I have not silently rewritten these. US3692249A and US3782647A appear after the '153's 1970‑01‑12 priority and are therefore not available as prior art on this record (I could not verify a pre‑1970 priority for US3782647A within my tool budget — treat it as unavailable unless a pre‑1970 priority is confirmed).

2. Element‑by‑element screen (anticipation check first)

No single reference anticipates. Neither cited reference discloses the whole combination:

• US 3,384,312 A discloses (a) base frame housing 10 with a feed opening and a concave ring 20 = crusher lining, (b) cylindrical hub 12 = tubular support post, stationarily mounted, with its lower cylinder opening closed by cylinder head 29, (c) piston 27 slidably fitted in cylinder 28, (d) hollow crusher mainshaft 25 with conical crusher head 57 / mantle 60 on top, (e) a step bearing assembly 55 (concave pressure bearing 50 over convex bearing 52) = dish‑shaped friction bearing, (f) eccentric 63 + ring gear 64 producing the wobbling/gyrating movement, (g) hydraulic fluid "pumped … into the lower portion of cylinder 28 to raise the piston 27" = the high‑pressure gap‑adjustment chamber, and (h) an axial conduit: "a fluid passage means such as tube 44, is provided through the hollow crusher mainshaft 25 communicating between the upper portion of the cylinder 28 … and the upper surface of head 26" (element (i), at least in substance).
  What is missing: element (j). The '312 lubrication fluid is fed by bore 45 through the side of the base frame, not by a tube secured to and passing through the bottom closure. The examiner's citation of this reference therefore covers (a)–(i) only.
  (https://patents.google.com/patent/[US3384312A](/patent/US3384312A)/en)

• US 1,717,894 A discloses elements (i)–(k) almost verbatim, but in a different machine architecture: a shaft 9 with an axial oil bore 15, whose lower end is tapered (15′) to receive the tapered upper end 16 of a yielding tubular connection 17 slidably mounted in a cap member 18 connected to the lower end of the inner hub; the cap has a threaded bore 19 for connection to a source of oil supply, communicating with the bore of connection 17; the connection carries piston rings 20; and the stated object is that "oil for lubricating the main bearings is introduced through a tubular portion of the crushing shaft by means of a yielding member which yieldingly bears against the lower end portion of the shaft," such that the "yielding connection permits vertical adjustment of the crusher shaft 9 while maintaining an oil tight joint."
  What is missing: the hydraulic adjustment chamber formed by the piston's bottom end and the post's closed bottom; the dish‑shaped bearing on the top of an axially sliding piston; the eccentric means.
  (https://patents.google.com/patent/US1717894)

Conclusion of the screen: claim 1 is not anticipated, but it is a textbook combination of two references in the identical art, each disclosing a different half of the claim — the §103 posture.

3. Ground 1 (primary): US 3,384,312 A in view of US 1,717,894 A

Disclosure made up by the combination.

• (a)–(h) and (i): furnished by US 3,384,312 A as set out above (housing/concave, tubular post with closed bottom, piston, cone, step bearing, eccentric, high‑pressure chamber, axial tube through the piston/shaft to the bearing).
• (j): furnished by US 1,717,894 A — a tube (17) secured to the closure (cap member 18) at the bottom of the stationary post, passing through that closure into the axial oil bore (15) of the moving member, in sealed slidable engagement (piston rings 20; "oil tight joint"), the seal accommodating vertical adjustment.
• (k): furnished by US 1,717,894 A — threaded bore 19 "for connection with a source of oil supply," i.e., external low‑pressure lubrication fluid fed to the outer end of the tubular member and thence to the bearing.

Motivation to combine (KSR/Graham factors).

1. Same field, same problem, same machine type. Both references are gyratory crushers with a vertically adjustable crushing member whose position must be maintained while oil is delivered to a bearing above the adjustment interface. There is no field boundary to cross.
2. The '312 patent itself supplies the reason. US 3,384,312 A frames its own contribution partly as reducing "lubricating fluid distribution complications," and it already runs an internal tube up through the shaft to the step bearing. Once the supply side is moved to the bottom of the machine, the only remaining question is how to bridge the moving/stationary interface — precisely the question US 1,717,894 A answered.
3. US 1,717,894 A states the very advantage the '153 patent claims. The '153's stated object is a feed whose "dimensions [are] independent of the diameter of the piston" and which can be applied "without expensive installation operations." US 1,717,894 A already teaches that a bottom‑mounted yielding tubular connection "permits vertical adjustment … while maintaining an oil tight joint," i.e., the sliding seal is placed on a small tube rather than on the piston's circumference. Under KSR, "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious."
4. The '153 specification's own criticism of the prior art points to the combination. The specification attacks the US 3,372,881 style annular chamber because it "requires … relatively large sealing devices … an inner diameter which depends on the exterior dimensions of the piston," which "wear very quickly," leak, and are "very difficult" to replace. A POSITA confronted with that criticism would be motivated to relocate the seal to a small‑diameter tube — the US 1,717,894 A expedient — with a reasonable expectation of success.
5. Predictable mechanics / no new technology. Axially fed tubes with sliding seals (O‑rings, piston rings, stuffing boxes) were routine in 1970; the '153 specification itself treats the alternative as trivial — it expressly notes the modification in which "the tubular pin [19] is rigidly connected with the piston 13" and passes slidably through the cover plate, with seals in the bore wall, and observes that "the sealing rings are then easily accessible." Choosing which side of the interface carries the seal and which carries the seal surface is a reversal/rearrangement of parts yielding predictable results (MPEP 2144.04). Likewise "threadedly attached … or welded or soldered" (spec.) is a routine design choice.

Separate low‑pressure lubricant vs. high‑pressure hydraulic fluid (element (k) vs. (h)). US 3,384,312 A itself keeps two fluid circuits: "a hydraulic lubricating fluid must be pumped through the bore 45 and into the top portion of cylinder 28 above piston 27" for the bearing, while "Another hydraulic fluid is pumped through inlet 30 … into the lower portion of cylinder 28 to raise the piston 27." The '153's "highly pressurized" / "low pressure" dichotomy therefore reflects a distinction already conventional in the art.

Result: claim 1 is prima facie obvious over US 3,384,312 A + US 1,717,894 A.

4. Ground 2 (alternative): US 3,532,277 A + US 1,717,894 A

US 3,532,277 A (Decker et al., KHD — the assignee's own earlier machine; filed 1967‑06‑09, published 1970‑10‑06, so prior art) is arguably a better primary reference for elements (c), (d) and (j)'s "through the closure" feature, because it discloses the hydraulic cylinder formed in the tubular main shaft whose "interior of the cylinder 18, 19 is at its lower end pressure‑tight closed by a cover 18′," with pressure medium "supplied from below by means of a trombone pipe 21 which preferably follows the piston movement in that it is kept in steady contact with the bottom of the up and down travelling piston 17, by means of a spring 22," plus spring‑loaded sliding mounting of the pipe (claim 7). Its set of pre‑tensioned springs and its radial lubricant port 20′ correspond to the '153's spring 14 and lubrication scheme.
(https://patents.google.com/patent/[US3532277A](/patent/US3532277A)/en)

Combining US 3,532,277 A (which already teaches a tube entering through a bottom closure into the interior of the hydraulic cylinder) with US 1,717,894 A (which teaches using such a tube to carry lubricant into an axial bore in the moving member through a sealed sliding joint, fed from an external supply) reaches claim 1 by substituting the trombone pipe's function from pressure delivery to lubricant delivery and adding the sealing rings — a substitution of one known function for another with predictable results. The spring‑biased slidable pipe mounting of US 3,532,277 A is strong evidence that "tube through the bottom cover accommodating axial adjustment" was, by 1970, a known design expedient in this very assignee's own crusher line, which directly undercuts any argument of unexpected difficulty.

5. Ground 3: the acknowledged art (US 3,372,881) as starting point

The specification itself concedes the entire combination except element (j): it describes the known crusher (US 3,372,881) as already having (i) a piston slidable in a stationary tubular shaft, (ii) a dish‑shaped sliding bearing at the piston top fed by an axial lubricating channel 17/18, and (iii) lubrication fed from outside the machine. The only delta is how the lubricant crosses the pressure‑medium space. US 1,717,894 A supplies that delta. Where the applicant's own specification concedes all but one element, the obviousness inquiry narrows to whether that one element was known — and it was, in the same art, for the same purpose, 41 years earlier.

6. Anticipated rebuttals, and how they fare

• "Different architecture / different class of crusher." Weak. US 1,717,894 A is a gyratory crusher with an axially adjustable crusher shaft and an oil bore in that shaft; US 3,384,312 A is a gyratory crusher with an axially adjustable piston and an oil tube in the shaft. The problem addressed (feeding a bearing above an axially moving interface) is identical.
• "Teaching away / the art favored annular chambers." Weak. The annular‑chamber approach (US 3,372,881) is an alternative, not a disavowal of tube‑through‑closure feeding; and the applicant's own criticism of the annular chamber (large seals, fast wear, hard replacement) is a reason to look at the alternative, not away from it.
• "Unexpected results." The stated benefits — seal diameter decoupled from piston diameter, accessibility, ease of assembly — are the direct, predictable consequences of shrinking the sealed diameter and placing the joint on the machine's bottom cover. US 1,717,894 A already recites the key benefit ("permits vertical adjustment … while maintaining an oil tight joint"). No evidence of results beyond expectation appears on the face of the patent.
• "Long‑felt need / commercial success." Not evidenced on this record. Even if shown, nexus would be difficult: the KHD assignee itself had been working this problem in US3532277A and US3692249A in the same period, which weakens any argument that the solution was beyond the ordinary artisan.
• "Claim is narrow (bound to the specific bottom‑closure geometry)." The breadth of claim 1 does not help; the narrower it is drawn to the tube/closure/sliding‑seal relationship, the more exactly it reads on US 1,717,894 A's connection 17 / cap 18 / bore 19 / piston rings 20.

7. Additional risk flags

1. Same‑family / same‑inventor sibling: US3692249A ("Lubricant feed means for gyratory crushers," the same three inventors, filed 1970‑12‑18, German priority DE 2000141 of 1970‑01‑02 — ten days before the '153's DE 2001073 of 1970‑01‑12, granted 1972‑09‑19). Because the inventive entity is identical, it is not prior art under pre‑AIA §102(a)/(e). However, it is a parallel KHD disclosure of an alternative lubricant route (lengthwise bore in the hollow shaft wall + longitudinal slot in the piston) leading to the same sliding bearing, and its existence supports the point that the lubricant‑routing choice was an ordinary design exercise for this assignee. If both patents were ever enforced together, obviousness‑type double patenting would also merit attention. (https://patents.google.com/patent/[US3692249A](/patent/US3692249A))
2. US3782647A / US3801026A / US3873037A appear on the page as "Similar Documents" with 1974–1975 publication dates; on the page's data they post‑date the '153 priority and should not be used as §103 art. I could not confirm their filing/priority dates within my tool budget — that verification should be done before relying on or excluding them.
3. "Similar Documents" not verified. I did not independently open US2079882A, US3057563A, US3345000A, or US3140834A ("Seal for gyratory crushers"); they are all pre‑1970 by date and are plausible corroborating art (hydraulic shaft support, sliding seal packings), but I will not characterize their disclosures beyond what the titles/lists show. This is a stated limit on my confidence, not a finding.

8. Conclusion

Claim 1 of US 3,891,153 A is, on this record, obvious under 35 U.S.C. §103.

The strongest ground is US 3,384,312 A (Patterson et al., Allis‑Chalmers) in view of US 1,717,894 A (Smith Engineering Works):

• US 3,384,312 A supplies elements (a)–(i) — the housing/concave, the stationary tubular support post with a closed bottom, the axially movable piston, the crusher cone, the dish‑shaped step bearing, the eccentric gyrating means, the high‑pressure gap‑adjustment chamber, and an axial tube through the piston to the bearing.
• US 1,717,894 A supplies elements (j) and (k) — a tube secured to the post's bottom closure, passing through it into the moving member's axial oil bore in sealed slidable engagement (piston rings) and fed from an external source, expressly to allow axial adjustment "while maintaining an oil tight joint."
• The motivation is supplied by (i) the shared field and shared problem, (ii) the '153 specification's own criticism of the large‑diameter annular‑chamber seals, and (iii) US 1,717,894 A's express teaching of the very advantage the '153 asserts — with predictable, routine mechanics and a mere rearrangement of which side of the interface carries the seal.

A parallel and arguably stronger form is US 3,532,277 A in view of US 1,717,894 A, since US 3,532,277 A already discloses a tube (trombone pipe 21) entering the pressure chamber through the bottom cover 18′ of a tubular crusher shaft, spring‑loaded to accommodate piston travel — reducing the '153's contribution to changing that tube's contents from pressure medium to lubricant.

Confidence: high that claim 1 is prima facie obvious over the two examiner‑cited references in combination; moderate on the precise mapping of "piston" in US 3,384,312 A (its crusher head is carried on a mainshaft bolted to the piston, which a POSITA would read as a piston assembly), and moderate on unverified "Similar Documents" art as noted above.