Drawing the UP’s auxiliary excursion train water tenders for N Scale

The Union Pacific railroad heritage fleet currently runs two of their preserved steam locomotives on regular excursion trips and, with the very much anticipated Bigboy No. 4014 re-entering service in the next few years, the modelling of the excursion train will become even more popular. With Athearn’s new N scale Challenger and Bigboy locomotives, or even the former Rivarossi models, and the Kato ‘City of Los Angeles’ cars, this can easily be done. The one important thing missing is the extra water tenders now always used for the long trips.

Ever since the switch from steam power to diesel the supply of water along the railroad has all but dried up; often you can see local fire department filling the excursion train locomotives water tanks with their pumping equipment at stops along the way. To combat this UP have created auxiliary water tenders which hold more water than the engine’s own capacity and greatly increases the range of the excursion trips. Currently, my understanding is, the UP has four auxiliary tenders in the heritage fleet.

Here is UP 844 in Oakland, California in 2009, accompanied by one of the auxiliary tenders whilst on an excursion trip stopover.

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These tenders started life as regular coal and water tenders for the 800-class steam engines until the engines where decommissioned due to the new diesels. However when the new 8500 class gas turbine locomotives, built by General Electric, started being used by the UP, the need for tenders to hold their bunker C fuel oil was created and the old 800-class tenders where recycled for this purpose. Because the bunker C fuel oil needed to be kept warm so it could be pumped as a fluid, the tenders were fitted with a heating system and a second metal skin for insulation and to cover the system. When the UP retired the 8500 Gas Turbines the tenders remained in storage until the heritage fleet commandeered them for the excursion trains. The heritage fleet used the tenders in this configuration until 2007 when two were rebuilt removing the heating system and the second skin. This increased the water capacity by 3000 gallons to 28,000 gallons. These two tenders were christened UPP 809 Jim Adams and UPP 814 Joe Jordan after two retired steam fitters from the UP repair shop.

I wanted to produce models of both versions of the tenders so I could replicate both periods (pre and post 2007). I decided to start with the newest incarnation and set about producing a 3D computer model.

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I used a mixture of images and drawings from the internet and books to get the correct dimensions.  There’s a 8500 gas turbine and tender at the Illinois Railway Museum and they have lots of good pictures, as do Wasatch Railroad Contractors, who did the conversion on water car UPP 814.

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Some elements were simply too small to be reproduced in N scale, such as the handrails that run along the top and up the ladders.  I decided that it would be best to add these using brass wire at a later stage.

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To make this easier to paint I separated some of the detail parts from the main model body.  The ladders, roof tool boxes, headlights and flag plates are all loose parts, as are the trucks, chassis and bolster pins.  Here are the parts laid out ready for the first test print.

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The body has been designed to take Micro-Trains body mount couplers.  The bolster pin that holds the trucks to the chassis has also been positioned off centre, unlike the prototype, so that the trucks can be removed without removing the wheel sets.

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In the next post I will show you how it came out and what improvements needed to be made before it was ready for the final print.