Front Flue Sheet Installation

New photos are now available from the Continental Fabricators factory floor in St. Louis showing Chicago & North Western 1385’s new boiler under construction. The new images mostly show the installation of the front flue sheet at the front of the boiler.

The front flue sheet (along with the rear flue sheet) support the flues which carry the smoke and hot gasses from the firebox – located at the rear of the locomotive – to the smokebox – located in the front of the locomotive – where they can then escape through the smokestack.

The front flue sheet also has multiple larger diameter holes for supporting the superheater flues. In a superheater-equipped locomotive such as the 1385, the superheater re-heats the steam generated by the boiler, increasing its thermal energy and decreasing the likelihood that it will condense inside the engine. Superheating the steam increases the thermal efficiency of the steam engine.

Lastly, the single largest hole in the front flue sheet supports the dry pipe. The dry pipe carries the saturated steam (i.e. non-superheated steam) from the steam dome to the superheater header before being directed to the superheater flues. Inside the superheater flues the saturated steam becomes superheated and is then directed to the cylinders, which in turn provide power to the driving wheels.

flue sheet before installation

C&NW 1385 new front flue sheet. March 21, 2018. Photo courtesy Gary Bensman.

The following two images show 1385’s old boiler to help give perspective of where the front flue sheet resides within the locomotive.  You may notice the pattern of the smaller holes for the tubes is different between the new and old sheets.

One advantage of building a new boiler is that we can correct some compromises made when the Chicago & North Western modified the engine to add the superheaters.  We can also incorporate an updated design for arch tubes in the firebox which will allow us to put tubes back into the area formerly blanked off in the old boiler.  The old boiler has a patch in the belly of the barrel to repair cracking believed to be caused by uneven heating.  Those thermal stresses were thought to be the end result of that bottom area of tubes being removed.  Another advantage of populating that area with flues again is a gain in heating area so the new boiler should steam a slight bit better.

The last image from St. Louis shows the hole cut into the top of 1385’s new boiler where the steam dome will be installed.

boiler steam dome hole

The large hole is where the 1385’s steam dome will sit. Photo courtesy Gary Bensman.

You Can Help Get C&NW 1385 Back in Service

Ever since the C&NW No. 1385 restoration was resumed in 2011 work has progressed steadily thanks in large part the financial support of the 1385 project’s enthusiastic followers. That financial backing has allowed hired professional machinists to work on the project 5-days-a-week and allowed progress to occur exponentially faster than could be accomplished by volunteers alone.

As we head in the home stretch we’re asking for your continued support so that the 1385 restoration can continue moving forward without delay. Please consider joining the growing list of nearly 1,000 project contributors by donating today. You can do so by visiting our Donation Page and specifying in the donation form that you want your contribution to support C&NW #1385.

Donating is easy thanks to our online donation form which accepts all major credit cards and Paypal, or you can use our printable donation form to send with your mailed contribution. Thank you for helping us get this far!

With your help this will soon be a common scene at Mid-Continent Railway Museum.

Disassembling 1385’s Pistons

Earlier in the rebuild of C&NW 1385, the cylinders were bored out to make them round once again. [See Nov. 26, 2015 post Driving Wheels and Frame Reunite].  The drawback of that operation is that now the pistons are a bit too small.  Usually the only way around this dilemma was to either build up the edge of the piston with bronze or make a new piston.  Fortunately for us, one of the decisions made over a hundred years ago is of great help to us today.

Location of cylinder/piston.

The C&NW decided to use a multi-part piston rather than a one piece casting in the R-1 class locomotive.  There are two cast steel follower plates that hold what is called a bull ring sandwiched between them and they are bolted together.  Once the bolts are extracted (or broken off) the front plate comes off and the bull ring slides off the rear plate.  The outside diameter of the bull ring determines the size of the piston and the bull ring also has 2 grooves in it to carry the packing rings that actually make the steam-tight seal against the cylinder wall.  A new bull ring for each piston will be machined to the proper size and fitted to the followers.

Both pistons tied down to the workbench for the process. Pete Deets photo.

One bull ring had been built up with bronze brazing rod as shown by the gold color in the below photo. One of the drawbacks in that approach is the heat needed to add the material can distort the shape of the bull ring which it did in this case and it made it difficult to remove from the rear follower.

Bull ring with bronze brazing rod buildup. Pete Deets photo.

An unanticipated find in this process was the bolts holding one piston together were quite badly corroded and several broke in the process of extraction.  As seen in the below photo, two of the bolts that didn’t break are severely necked down.  All new bolts are being produced to ensure the pistons hold together for a good long time.

Worn bolts. Pete Deets photo.

 

Washout Couplings and Plugs

An important part of caring for a steam locomotive is time-honored boiler wash. Performing boiler washes at regular intervals is mandatory to conform with Federal Railroad Administration regulations and ensures that the locomotive’s boiler is kept free from all corrosion and scaling which would otherwise lead to reduced operating performance and eventually cause damage to the boiler. Boiler washes must be completed after every 31 days the locomotive is in service and is one of the many steps of regular maintenance required to keep a steam locomotive operating. During a wash the boiler is first emptied and then high-volumes of water are flushed through the interior of the boiler and smokebox until no sign of rust, scale or other detritus is detectable in the drainwater.

In order to perform a boiler wash, it is necessary to have numerous access points to the boiler’s interior to direct the water into the boiler as wells as locations for the drainwater to escape. This is achieved through the use of removable plugs of a decent size that can easily be removed and put back in with a steam tight seal.  SPEC Machine is reproducing steam era Huron style [Huron Manufacturing, Inc.] couplings and plugs from certified materials for the task.

washout couplings arrayed on table

New washout couplings for C&NW #1385. Pete Deets photo.

sample washout coupling and plug

New washout couplings with sample plugs from the C&NW #1385’s old boiler. Pete Deets photo.

The couplings will be welded into the boiler shell and the two plugs shown in the above photo (which are actually from the 1385’s old boiler) demonstrate how the plug sits in the coupling and also shows the wide sealing surface that makes the Huron style so easy to use.  With a clean thread and sealing surface a gentle tap or two with the heel of your hand on the end of an 18-inch wrench is all that is needed for a perfectly steam-tight fit.  Much more force than that will only distort the plug and seat and ruin the sealing surface.

bronze rods

SPEC Machine’s Steve Roudebush opens a shipment of new bronze rods which will soon be formed into washout plugs for 1385’s boiler. Pete Deets photo.

Recently the steam bronze arrived for the new plugs and was photographed being unboxed by SPEC Machine’s Steve Roudebush.  Those two sticks total over 300 lbs. of material.  The next step is to whittle away anything that doesn’t look like a Huron plug.

Engineering calculations show the threads should be able to withstand pressure up to 13 times greater than the boiler’s design pressure but calculations alone aren’t good enough. One extra coupling was made to serve a dual purpose.  First, it will be welded into a piece of test material so we can gauge how badly the heat of the welding process will distort the coupling.  The test material will also have a fitting applied to allow the 1385 team to hook it up to the hydrostatic pressure test pump.  Once a plug is made, it will be screwed into the coupling and can be pressure tested as a system to further prove the safety of the design before it gets installed on the actual boiler.

Meanwhile in St. Louis, Missouri, Continental Fabricators has continued production work on the new boiler. This photo recently shared by Continental Fabricators’ staff shows the front courses welded together.

three boiler courses welded together

Welded front courses of Chicago & North Western #1385’s new boiler. March 5, 2018. Photo courtesy Continental Fabricators.

Lots and Lots of Staybolts

A brief update to yesterday’s discussion on staybolts:

SPEC has received the stock to be used for C&NW No. 1385’s rigid staybolts and is cutting it to the length, engraving the heat number and drilling the tell-tale holes per Continental Fabricator’s specifications. There will be over 1000 new rigid staybolts created in all, cut to five different lengths as required by 1385’s boiler.