Friday, May 29, 2015

Tender work will soon be behind us

The tender tank rehabilitation and restoration work for Northern Pacific Railway 0-6-0 steam locomotive 924 is drawing to a close!  The 19th Century Rogers-built locomotive is the subject of a major collections care effort inside the Northwest Railway Museum's Conservation and Restoration Center in Snoqualmie where the first order of business is the tender and its badly deteriorated water tank.  The building of a new riveted cistern for a steam locomotive is a lot of hard work, and is not often undertaken at heritage railroads. 

Erecting major components such as sides, ends, and slope sheets can usually be accomplished quickly. In the non-museum world, a similar vessel would be put together using modern fabrication techniques such as welding, and the project would have been completed months ago.  However, in order to adhere to the Secretary of the Interior Standards for Treatment of Historic Properties, fa├žadism is not an acceptable practice. Instead, it is critical to reuse original fabrications and components to the greatest extent practicable, and when infeasible, faithfully recreate the missing or irreparably damaged fabrications using materials and techniques consistent with the original.  So for the tender cistern, every rivet has been or will be duplicated using the technologies of the era.  For instance, each corner seam  is riveted to an angle iron on both sides of the angle with 1/2 button head rivets on a 1 1/2" pitch requiring literally thousands of precision drilled holes. 

Since the last report, the top deck of the tender tank has been fitted and installed.  Historically, for this portion of the tank, flush head "Liverpool" style rivet heads were used for the majority of the work.  This was done so that coal could be scooped from the top deck without hitting the higher "button head" style rivets.  This feature has been faithfully reproduced on the new tank. 

In addition to the structural riveting, the tank continues to receive original castings and forgings with the installation of tie down brackets and hand rails. The side coal boards were also added, giving the cistern that iconic 19th Century everted lip tender look.  Moving forward, this coal board will soon be extended and wrap completely around the rear of the top deck, and the original water hatch will be rehabilitated and installed. 

In addition, to the ongoing cistern work, the tender frame has received attention for its return to service.  This frame had been extensively rebuilt in the 1970s due to an encounter with a runaway freight car while being stored in Centralia, WA, and most of the wooden framework remains in remarkable condition.  However, aesthetically the timbers exhibited surface weathering and other effects which would not present well in the final product.  In order to rectify these issues and assure many decades of trouble free service, the surfaces have been sealed and filled using epoxy-based fillers and sanded to fill any minor cracks and surface blemishes.  (This technique was extensively applied to chapel car 5 Messenger of Peace.) The frame will be primed with epoxy-based primer Awlgrip 545) and top coated with a finish coat of black.  Once this work is completed, the tank can be installed on the frame and bolted down.  Following this step, the tender trucks will be rebuilt so as to assure like-new performance from the tender. 

The 924's tender will be completed this summer.  At that time, work will shift to the locomotive boiler, running gear, and cab.  And the 924's tender just might see some early service in support of the Museum's steam program.

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