The assignee ranking covers 100 companies, with the leader holding 160 records and the fifth-place company holding 78. The top 5 combined account for 12.3% of the 4,595 records in scope, and the top 10 account for 19.8%, which indicates a moderately concentrated field rather than one dominated by a single company. Automotive and industrial friction-material specialists appear alongside diversified industrial conglomerates, reflecting that much of this filing activity originates in automotive brake technology that is adjacent to, or transferable into, rail applications.

Both fall under the same search scope because friction pairs (pad and disc) are usually claimed together or tested together on a bench rig, but the IPC breakdown shows the underlying chemistry differs: ceramics and refractories (C04B, 7.4% of records) tend to relate to disc and rotor composition, while polymer compositions and additives (C08L, C08K) more often describe pad binder and filler systems. F16D, the largest single category at 62.9%, covers the clutch-and-brake mechanical assembly that both pad and disc claims typically reference.

Filings peaked in 2017 at 194 and fell to 91 by 2024, a 36% decline over the 2021-2024 window using the most recent years that can be treated as complete. Data for 2025 and 2026 is still incomplete because publication typically lags filing by around 18 months, so those years understate actual filing activity and should not yet be read as confirming a continued slowdown. The honest read is that activity has cooled from its 2017 peak but the trajectory of the last one to two years is not yet visible in the published record.