Assignee
SCHALK DAVID A
4 granted patents·15 citations·filing 2007–2020
Technology mixB61L4
Top patents by PatentIndex Score
4 records- 0184US11919553B1Railroad switch position indicatorSCHALK DAVID A·Filed 2020·Granted Mar 5, 2024·2 cites·15 claims
- 0269US8695928B1Railroad switch indicator with distance amplifierSCHALK DAVID A·Filed 2010·Granted Apr 15, 2014·6 cites·14 claims
- 0362US10766511B2Cable driven railroad switch indicatorSCHALK DAVID A·Filed 2018·Granted Sep 8, 2020·1 cites·10 claims
- 0457US7735784B2Railroad switch indicatorSCHALK DAVID A·Filed 2007·Granted Jun 15, 2010·6 cites·15 claims
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