The Ridgway Spark Arrestor - also known as "bear trap" spark arrestors" - were a unique design by H.W. Ridgway, the C&S? Superintendent of Motive Power. They were first designed around 1917-1918, and were patented on 16 Aug 1921 as US Patent #1439262.
The nickname "bear trap" was never used by the railroad itself, but was coined by notable railfan Lucius Beebe.