Within this dataset the ranking is led by a single assignee with 12 records, well ahead of the fifth-place company at 1. That gap indicates one long-standing filer built a substantial position early, likely tied to the oldest and most-cited wear-liner patents in the set, while the rest of the ranking is a long tail of companies with a handful of filings each. Because the ranking counts patent families rather than raw publications, this reflects distinct inventions rather than continuation filings inflating the count.

Crushing, grinding and pulverising equipment (IPC class B02C) covers 85.7% of the 21 records in scope, confirming that most patenting activity addresses the core mechanical crusher design rather than adjacent fields. Smaller secondary classes — ceramics and cement, polymer additives, and roads and pavements — each appear on about one in ten records, usually as a downstream application context rather than a distinct filing cluster. Powder metallurgy, microorganisms, polymer compositions and metal extraction each show up on only a single record, marking them as thin, exploratory intersections rather than established sub-fields.

Filing activity rose to a peak of 6 records in 2022, then fell to 0 by 2024, a -100% change over that three-year span. That decline should be read cautiously: publication typically lags filing by around 18 months, so the most recent one to two years in any filing trend are understated by definition and are not yet a reliable signal either way. What can be said is that the 2021–2024 window shows a real drop-off from the 2022 peak, not a plateau.

US4690341A, held by Hise, Mason R., is the most-cited record in this dataset at 55 citations and claims a specific dovetailed, repositionable wear-ring and liner mechanism inside a side-discharge impeller housing. It blocks that particular interlocking liner geometry and the ability to reposition the wear ring at least three times, not impact crushing or wear-liner design generally. Teams working on bolt-on wear plates, cast liner segments or non-dovetailed designs sit outside its specific claim language, though they still need to clear the rest of the crowded B02C prior art.

The thinnest-documented intersections in this dataset are powder metallurgy, microorganism/genetic engineering and metal extraction and refining, each appearing on only one of the 21 records — too sparse to call an established sub-field but also largely unclaimed. Co-assignee filing is also rare, with only two co-filing pairs across the whole set, suggesting collaborative claims that combine mechanical crusher design with materials-science limitations (such as specific abrasion-resistant alloys tied to a rotor tip speed range) are largely open. Any filing strategy in these areas should still run a full clearance check, since thin documentation here may reflect the search terms rather than a genuine absence of prior art.