Railroad Trains for the Soul: Locomotive Air Conditioners (featuring the NS "top hats")
It's a very hot week in my town and my old house has no central air conditioning but, of course, I still survive thankfully. One of the things that makes me live comfortably, especially in extreme weather temperatures, is my appreciation of railroad workers who kept the economy going, even before air conditioning became widely available for locomotives. We all know that steam locomotives can be very hot, dirty, and laborious to operate; it can also be worse in the heat of summer. When diesels began to replace steam after World War II, they tended to offer much cleaner and more comfortable cabs without any soot or grime, but air conditioners (or A/C units) were still not yet available for most diesels until recent decades.
Depending on the type of locomotive, A/C units may be mounted directly on the top of the cab, on the walkway, or under the floor. On standard-cab road-switcher diesels like the Norfolk Southern narrow-nose DASH 9-40C, the air conditioner can be easily spotted on the rooftop above the cab. For that reason, these NS locomotives are often nicknamed "top hats". In recent years, many standard cabs have been retrofitted with A/C boxes, but some others, including the C40-9, were originally built with pre-installed air conditioning.
On General Electric wide-cab diesels such as the DASH 8-40CW and the DASH 9-44CW, there's a square box immediately behind the cab on the conductor's side (or left side) of the locomotive; it's where the air conditioner is mounted. When GE introduced the AC4400CW, the length of the left-side box was increased to house the inverter cabinet for the AC traction system; so the air conditioner was relocated under the cab floor on the same side as the large box, which makes the AC44 different from the DASH 9. The underfloor A/C unit became a standard feature on subsequent GE freight locomotives as well as the passenger-duty GENESIS series.
Electro-Motive has been offering underfloor air conditioning on many of its comfort-cab diesels. This configuration is usually spotted by looking at the exhaust louvers above the front truck on the conductor's side. On the engineer’s side of the cab, there are typically some access doors to the electronic air brake equipment. If you can't find the cab louvers or the rooftop A/C box, it could mean that there is no air conditioning in a particular locomotive. For example, Canadian National and Canadian Pacific chose not to add air conditioning into their cowl diesels when they were newly built. Because of their full-width bodies, they are ideal for colder winters in Canada. Even the CN fleet of GE DASH 9's were delivered without A/C as you can tell from the absence of the square box behind the cab. Some EMD passenger diesels, like the F40PH and F59PH, did not have air conditioning until they were retrofitted with rooftop A/C units in their later years.
Today, virtually all of the new North American freight and passenger road locomotives from both Electro-Motive Diesel (owned by Caterpillar/Progress Rail) and GE Transportation (now part of Wabtec) have the standard underfloor air conditioning for the best crew comfort in a world of climate change concerns. Interestingly, Progress Rail offers special lithium-ion batteries that can supply power to the A/C for up to six hours without requiring the diesel engine (source: Locomotive Lithium-Ion Battery).
Photo credit: GenericRailfan
