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Hello Bill and All - In the early days - during WWII and in the immediate post-war years - there were control problems when trying to run locomotives from different builders in multiple unit sets. Baldwins lived in a world of there own (someone check me on this) with pneumatic controls. ALCo locomotives loaded differently than EMDs and made
starting a heavy train a real challenge for the engineer. Eventually the railroads got different types to play together nicely. The 27 wire m.u. connecting cable between units became standard, electrical loading characteristics were adjusted, and automatic transition became the norm. Almost. Into the 1960s
there were FT, F2, and F3 locomotives with manual transition - the locomotive engineer had to use a lever on the control stand to 'shift' the electrical power circuits as train speed increased. This is why you see photos of older units leading brand new ones. They'd be stuck in 'low gear' if they were trailing. Gear ratios were a problem 'way back when' - switch engines being towed in a train were limited to 35mph or so. Newer switchers with road trucks could run fine with the big boys. At the other extreme, putting an old F2 behind an E9 and running 100mph would tear up the gearing and the traction motors on the freight unit. Horsepower ratings do not have to be matched. If the locomotive engineer opens the throttle to 'Run 4' the big unit will deliver half its
power and the trailing GP7 will deliver half of its power. Wide open, both units will deliver their maximum power. This won't 'burn up' the GP7 - it will do what it was designed to do and put out 1500 horsepower. Nowadays the big freight units have all of their power output computer controlled. PAW . From: "wscott@optonline.net" <wscott@optonline.net> To: CBQ@yahoogroups.com Sent: Monday, February 10, 2014 10:48 AM Subject: [CBQ] compatibility of engines I've seen pictures of engines of various types mu'ed together, and I wonder, are there any rules about mu'ing dissimilar engines, or can any engines be mu'ed, regardless of the manufacturer, gear ratio or horse power? Are there any considerations that the railroads use in linking engines?
Bill Scott __._,_.___
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