Tag Archives: smokebox

No Minor Detail

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When it comes to the proper operation of a steam locomotive there is no minor detail.  Every piece must perform properly.  That extends all the way to the clips or “dogs” that hold the door shut on the front of the smokebox.  You may ask why and I hope to explain. 

C&NW #1385 at Mid-Continent Railway Museum. Enlarged detail of door dogs.

First and foremost to work efficiently a locomotive must generate steam well and in great quantity. One of the factors that figure heavily is how much air is drawn through the fire to ensure plenty of oxygen to support the combustion of the fuel.  That air is drawn by the creation of a partial vacuum in the smokebox of the engine.  That partial vacuum is created by directing the exhaust steam from the cylinders up through the exhaust nozzle and into the petticoat pipe at the base of the smokestack.  The exhaust is moving at a very high speed and because there is an open space between the nozzle and petticoat and due to the shape of both devices it will pull some of the gases in the smokebox along with it up and out the stack. 

simplified illustration of steam locomotive smokebox and placement of door dogs
Simplified illustration of a traditional steam locomotive smokebox, showing creating of draft and placement of door dogs.

Mother Nature is always following the path of least resistance so if there is a vacuum leak around the smokebox door air will be drawn in from there first rather than the more difficult path of up through the fire bed and down the tubes & flues to the smokebox.  If there is a leak at the door the engine will not steam well and efficiency suffers.  This is why the door dogs are important in that they must clamp the door down evenly on the gasket all the way around the edge in order to get a good vacuum seal.  Having the dogs a uniform size & shape makes it easier to judge when each has been properly tightened down.

The door dogs removed from C&NW #1385 were a mix of original castings, castings salvaged from other locomotives, and simple angle irons used in the place of missing castings.
  • Source material for a new door dog.
  • Partially completed door dog.
  • Partially completed door dog.
  • Completed door dog.
  • Completed door dog.
Newly created door dog next to versions removed from the C&NW #1385.

C&NW #1385 Update – January 2021

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With January coming to a close it is time to check in again with Chicago & North Western #1385’s progress. Steve Pahl, MCRM General Foreman of Steam, provided the following list of work being performed or recently completed as of January 20, 2021.

Key areas of work on C&NW #1385 during January 2021.

  1. The auxiliary steam dome is currently being repaired. The auxiliary steam dome is where the safety valves, boiler vent valve, and whistle are mounted. The boiler vent valve is used for filling the boiler with water and serves as a vent when draining said boiler. The whistle, of course, is the epitome of steam railroading! 
  2. The cast iron blanks for the new piston bull rings have been water jet cut to rough dimensions and are ready to be machined to the final dimension with grooves cut for the piston rings. The center “donut hole” left over after the piston bull rings were cut out are being used as the blanks for the two smaller bull rings that are needed for each valve. That way there is not nearly as much waste in material lost.

    One of the cast iron “blanks” for the new piston bull rings, shown after being water jet cut to rough dimensions. Further machining is required. Steve Pahl photo.

  3. A valve cage is a hollow cylindrical wear element that is used as both a guide for the valve as well as the outer sealing surface for the valve so it can route both the live steam and exhaust steam to the proper places. The valve packing rings form the inner sealing surface and slide back-and-forth in the valve cage as the valve is moved.

    C&NW 1385’s new valve cages stand ready to be installed into the steam chests. Steve Pahl photo.

    There are two sets of ports that have been machined into each cage. The large rectangular ports lead to the exhaust nozzle up to the smokebox so the exhaust can be pointed up and out of the smokestack. The smaller parallelogram-shaped ports lead to the passage to the cylinder. Depending on the position of the piston valve inside the cage either the live superheated steam is routed into the cylinder to push the piston forward or back or the cylinder is connected to the exhaust passage to release the steam once it has done the work of pushing the piston. Since steam pushes the piston in both directions there are ports needed for each end of the piston travel and the need for a cage at each end of the steam chest.

    The valve cage on the locomotive’s engineer side has been previously cleaned up by boring and was found to be thick enough to still have a long service life ahead and was therefore left in place. The fireman’s side valve cage was found to be in need of replacement. The new fireman’s side valve cages are now ready to be installed into the steam chest. This will be an interesting process to install. The valve cages will be shrunk using dry ice. In the meantime, a couple of rosebud oxy/acetylene torches will be used to expand the steam chest and if everything goes correctly, the valve cage should slide right in. One cage will be inserted from the front side of the steam chest while the other will be inserted from the rear.

  4. Fire doors have been painted and await installation. A “spacing” ring needs to be fabricated that will fit between the boiler and the firedoor itself. This is necessary for operational clearance. Due to the change from threaded and peened staybolts to the now welded staybolts, which was by design of the new boiler.
  5. As mentioned in the December update, the air compressors are awaiting installation. With the new boiler design, there needs to be adjustments made to the mounting brackets and boiler studs to ensure the proper placement as it appeared when MCRM purchased the locomotive. This will also be necessary for the power reverse due to the same circumstance.
  6. SPEC Machines made a tool for resurfacing and lapping the seats and flanges on the steam delivery pipes, the superheater header, and the steam chests. This ensures a tight seal for delivering the superheated steam from the superheater header to the steam chests. Work on these existing sealing surfaces is now complete. Yet-to-be-made matching “donuts” will be inserted between the branch pipe and steam chest flanges and the branch pipe and superheater header to adjust for minor manufacturing size differences and space variations between the new and old components.
  7. The smoke box has been seal welded to the boiler. This procedure finally secures the smoke box to the boiler itself. As reported last month, SPEC Machine was busy drilling and reaming the holes that connect the smoke box to the cylinder saddle. I am happy to report that the smoke box is in fact bolted down to the cylinder saddle with 50 tapered fitting bolts custom made by SPEC Machines with 50 H2 heavy nuts.  The boiler is now officially attached to the frame!  There is still some work to be completed with the smoke box; i.e., complete the grouting at the bottom of the smoke box with refractory, install smoke stack and assorted draft appliances.

50 custom-made tapered bolts now help secure the smoke box to the cylinder saddle. Steve Pahl photo.

“Drawing” Conclusions on C&NW 1385

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On the afternoon of Friday, February 24, 2017, the C&NW 1385 Task Force received the latest packet of shop drawings for the new boiler from Continental Fabricators for Mid-Continent to markup and approve. The painstaking process was started the following day at SPEC Machine and great progress was made.

Boiler review meeting

A C&NW 1385 boiler review meeting is held on, Feb. 25, 2017. The locomotive’s running gear and cab are just visible in the far left background. Photo courtesy Pete Deets.

Previously, Brett Morley of Performance Engineering had completed a SolidWorks™ 3-D model derived from countless hours measurements of the original boiler by him and others on the 1385 team as well as a study of the Chicago & North Western’s drawings for the locomotive, obtained from Lake States Railway Historical Association. The model provides a 3-D representation to check, among other things, whether and how well all the parts will fit together. Files derived from the model were provided to Continental Fabricators who then created their own preliminary construction drawings that are now being sent back to us to proof, mark up and return. The packet received on February 24th is the latest iteration.

boiler drawings

CNW 1385 boiler drawings undergoing review. Feb. 25, 2017. Photo courtesy Pete Deets.

The 1385 team must examine every minutia of the shop drawings to prevent any mistakes. It is a very painstaking and tedious process but the manufacturer will build precisely what is on the paper and it is Mid-Continent’s responsibility to make sure what is there is what we want and need.  

A few of the many details being reviewed include:

  • Diameters and shapes of each course
  • Overall length of the boiler
  • Mud ring size, shape, placement, and material
  • Shapes and placements of clearance holes
  • Size & placement of washout plugs
  • Placements of the throttle/superheater header/branch pipes
  • Size and placement of the safety valve outlet and appliance manifold outlet
  • Placement and size of cutouts in the smokebox

Every dimension on every drawing is going to be checked. Every description of every weld called out will be cross checked. The material listed for each part will be checked. These things will each be cross referenced against the C&NW drawings, actual measurements of the old boiler, and the SolidWorks™ model.

CNW 1385 drawings on table

The CNW 1385 boiler review meeting team sets up shop at SPEC Machine. Feb. 25, 2017. Photo courtesy Pete Deets.

With a project this scope, any mistakes are forbiddingly expensive so the team is proceeding as swiftly as they can without rushing the job. As the first round of checking concluded on Saturday, a fair sized chunk of the job has been completed. So far the Task Force have been quite pleased with what has been supplied from Continental and when finished, all the corrections will be sent back to them. Once those corrections are applied, Continental will send another packet and the process will repeat until there are no more corrections. Despite the intense workload on the Mid-Continent volunteers and partner contractors, the project is staying quite close to the manufacturing timeline and we are getting ever closer to the actual build.

Preparations to Remove the Boiler

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A work session was arranged for Saturday, January 7, 2012 to continue work started before the holidays on the Chicago & North Western no. 1385. The primary goal in these recent work sessions has been to remove exterior appliances from the locomotive boiler and frame. This work is being done in preparation for boiler removal from the frame and the shipment of the running gear to a shop for rebuild. Having sat idle and exposed to the elements for much of the time since it last operated in June of 1998, removal of many of the pieces have proven to be no easy undertaking and to make matters even more difficult, items like the running board brackets have not been removed from the boiler in many decades.

The crew for the day was led by Ed Ripp and Pete Deets. Assisting were Kelly Bauman, Richard Colby, and engine house first-timers Adam Stutz and Jeffrey Lentz. Jim Busse was also on hand and performed some much-needed cleaning and organization of the engine house and surrounding area.

With the 1385 parked in the engine house and the large south door open to let in the sun and unseasonably mild temperatures, work began. Pete, Ed and Richard all took turns climbing into the smokebox to clean rust from the blast pipe and smokestack mountings. Removal of the engineer side air reservoir brackets also took place. Work proceeded slowly as the rust necessitated most bolts be cut with a torch.

Close quarters between the 1385 and the engine house wall on the fireman side of the locomotive required that the R-1 be towed by MCRY no. 4 to a location just outside of the engine house to reduce fire risk from the shower of sparks. Once outside, work was able to proceed on removal of the air reservoir tank brackets and running boards. Work also began on the removal of the smokestack. With the more advanced work left largely to Pete and Ed, restoration newcomers Richard, Adam and Jeffrey took on the removal of the pilot support brackets at the front of the locomotive, a job suited to their flexibility.

Work continued as darkness descended. Finally, with too little light to safely continue, work was halted at about 6 pm and the 1385 was rolled safely back into the engine house to await the next work weekend.

 

January 14-15, 2016 Work Session Update

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Al Joyce reports:

“Just a work update on this past weekend. In short we made progress in the positive direction.

“Jim Connor and Ron Kokemuller drilled out the front tube sheet with the pilot holes (170). They did not do anything about cutting the larger holes because the core drill was only 2 inches instead of 2 1/16. One of the holes has a broken drill bit in it. That hole was marked for future work.

“Ed Dench worked on the smoke box by grinding the heads of the flush rivets. They look good. One may need some work as it did not fully fill the hole.

“With the combined help of Bryon Schumacher and Jim Connor, we got many more studs sized and installed in the boiler. They are in only hand tight so they can be removed. The boiler is starting to look like a porcupine with all the studs sticking out. Jim took some pictures so we hope to get them on the web site soon. With the help of Jim and Bryon we have doubled the stud crew membership. All the Stud Guys are qualified to work unsupervised at a pace that is comfortable to them.”

Jim Connor photos.