The Patent Finder
US

Electro-Proportional Pressure Control Apparatus

US 4,055,197 Term ended
OverviewSources & methods

Term ended no later than Oct 25, 1997 · Low confidence

Held by Aerocontrolex Group, Inc.
Application 05/721,936 · Granted Oct 25, 1977
None
Term adjustment
No prosecution delay on this record.
None
Terminal disclaimer
No disclaimer on this record.
Did not apply
Maintenance fees
Maintenance fees apply only to applications filed on or after Dec 12, 1980 (35 U.S.C. 41(b)).

How we calculated this date

One row per rule, each showing its own input and what it did to the date. A step we could not verify says so instead of resolving itself.
Step Input Date after this step Confidence
Grant dateAs the patent's record gives itOct 25, 1977High confidence
Statutory bound, 35 U.S.C. 154A patent term runs 17 years from grant or 20 years from filing, and either ends no later than 20 years from grant. The record gives no filing date to compute the exact term end from, so the date is a boundno later than Oct 25, 1997Low confidence

Sources

Google Patents · The patent document at USPTO · Assignment records at USPTO

USPTO account required: This application in Patent Center · USPTO's maintenance fee lookup

Maintenance fee events come from USPTO's own fee records. Its fee lookup asks for the patent number and the application number.

Not on this page: the patent's family, its recorded assignments and its citation count. USPTO's assignment records, linked above, list every recorded assignment.

Every date shows its work: the base term, any term adjustment or extension, any disclaimer cap, and the maintenance fee record, each with a confidence tier. How this record was built

Computed patent terms end on the dates shown. Related patents and pending applications may cover overlapping subject matter.

The Patent Finder CompaniesExpirationsCalculatorWatchlistPricing MethodologyCorrectionsLegalPrivacysupport@thepatentfinder.com Updated Nov 15, 2026 · includes USPTO assignment & status data published Nov 15, 2026 and grant & fee data published Nov 10, 2026 (weekly) Part of 137 Finder · © 2026 137 Finder LLC · Sources cited