Thursday, November 30, 2006

Cab Forward Locomotives

From: KyleWyatt@aol.com

A bit of history on the Cab Forward design. It's clear that the primary reason for the design was to prevent crew asphixiation, not to provide visibility. As evidence, none of the other Southern Pacific (SP) steam loco designs included cabs in the forward position. And clearly there were mixed emotions among crews over the visibility/exposure issues.

The traditional lore says that the SP got the idea for the cab forward design in 1909 when someone remembered the narrow gauge cab forward built by the nearby North Pacific Coast Railroad (NPC) in 1901 as #21. This loco included an unusual water tube boiler of a patented design (patent #682,765, application filed June 20, 1901, patent granted Sept 17, 1901), plus a separate design patent for the cab forward feature (design patent #35,806, application filed Nov 25, 1901, patent granted March 11, 1902). The NPC sued the SP over patent infringement but SP successfully argued that the NPC design patent included many features specific to the unique boiler design used by the NPC, and that in any case simply placing the cab in front was not a patentable idea.

However, design patent not withstanding, I'm confident that the cab forward design was in fact not the original idea of the NPC. An Italian designed 4-6-0 with it's cab located forward was exhibited at the 1900 International Railway Congress in Paris, with photos and information published in the US railroad trade press in 1901. The drawing accompanying the original NPC boiler patent showed a cab in the common location. It was only in the later NPC design patent that the cab forward idea was presented. My belief is that the NPC designers saw the Italian locomotive in the trade press articles, and incorporated the design into their new locomotive.

As an interesting side note, it is generally stated that the cab forward design required oil fuel. The NPC boiler was specificly designed to burn oil, and the later SP locos were also oil burners. But the Italian loco was a coal burner, with coal stored in coal bunkers along the sides of the boiler and looking like side water tanks. Actually, water was carried in a fillowing tender.

Both the Italian design and the SP design were successful, with locomotives having long service lives and modernized designs used on later locos. However the NPC loco had only a short life. Crews didn't like the unusual design, and apparently the boiler design proved hard to maintain.

—Kyle