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.
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.
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.
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.
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!
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.
Two cast iron blanks which will become C&NW #1385’s piston and valve bull rings. M.L. Deets photo.
This photo from February 2017 shows 1385’s disassembled piston. One of the bull rings is circled. M.L. Deets photo.
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.
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.
Another view of the new valve cage. Steve Pahl photo.
Comparison view of the old damaged valve cage that is being replaced. Jeffrey Lentz photo.
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.
Looking into the fireman’s side steam chest where the new valve cages will be inserted. M.L. Deets photo
This broader view shows the engineer’s side of C&NW 1385. Unlike the fireman side, the valve cage (circled) on the engineer side was left in place after boring. M.L. Deets photo.
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.
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.
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.
Flange atop one of 1385’s steam chests showing the new seat surface that has been cut. Tyler Roudebush photo.
Flange atop the other of 1385’s steam chests. Tyler Roudebush photo.
Newly machined sealing surface at the bottom end of the branch pipes. These carry the steam from the superheater header to the steam chests. Tyler Roudebush photo.
Top end of the 1385 branch pipes with newly machined sealing surface. Tyler Roudebush photo.
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.
Outside view of bolts securing the smoke box to the cylinder saddle. M.L. Deets photo.
Detail view of the seal weld and bolts along the bottom of C&NW 1385’s smoke box. M.L. Deets photo.
Detail view of the seal weld and bolts along the bottom of C&NW 1385’s smoke box. M.L. Deets photo.
Ever since the C&NW No. 1385 restoration was resumed in 2011 work has progressed steadily thanks in large part to 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 much 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.
In the second half of December, Steve Pahl, Sr., Mid-Continent’s General Foreman of Steam Power took photos of 1385 at SPEC Machine and reported the following recent progress and items coming up in the immediate future.
Work Areas (correspond to numbers in the below list).
The saddle bolt holes have been drilled and are in the process of being reamed. The saddle bolts still need to be produced.
Pistons and rods have been returned with the piston rod and re-trued (cut on a lathe). The pistons themselves are ready to be reassembled.
The valve slides should be ready for heat-treating in January 2021.
The crosshead slide drawings are complete and are awaiting machine time.
The furnace bearers along with all components are fitted and ready for final securement after the smokebox is secured to the saddle.
The two 9-1/2″ air compressors shown being test in the previous 1385 will soon be mounted in their rightful location on the fireman side of the locomotive.
The firedoors will be painted by early January in preparation for installation on the backhead.
Superheaters have been installed and preliminary testing is completed. They still need to pass final hydro testing.
SPEC Machine hopes to have the smokebox completed by the end of January 2021, in as far as it will be:
Secured to the saddle with bolts.
Grouted (to fill the voids between the cylinder saddle and smokebox and help make the two pieces become one)
Have the smokestack installed
And have the draft appliances installed, including the petticoat pipe, spark arrester, and associated components.
Saddle bolt holes have been drilled in preparation of final securement of the firebox and boiler to the saddle. View is looking up at the ceiling from the cylinders. S. Pahl photo
1385’s piston rods have been re-trued and ground to a finish. S. Pahl photo.
Furnace bearers and related components are fitted and ready for final securement of the boiler. These bearers allow the boiler to expand and contract while still being supported by the locomotive frame. S. Pahl photo.
Another view of the furnace bearers. S. Pahl photo.
View inside the smokebox of the saddle bolt holes (holes in the floor of smokebox). S. Pahl photo.
Reaming is underway by SPEC Machine. S. Pahl photo.
The saddle bolts will be inserted through the holes to secure the boiler to the saddle and locomotive frame. This is the only point where the boiler is solidly affixed to the frame. S. Pahl photo.
The throttle operating rod and stuffing box is what allows the engineer to control how much power is applied to 1385’s driving wheels. The throttle rod reaches through the stuffing box mounted on the backhead to the bottom pin hole of the bellcrank mounted on the throttle body. When the engineer pulls out on the throttle rod the bellcrank turns that motion 90 degrees, pushes up on the spool in the throttle body and opens the steam passage to allow the superheaters to fill and supply the cylinders.
1385’s stuffing box is located near the very top of the backhead – the portion of the boiler that extends into the cab. The large opening toward the bottom of the image is where the firedoor will be located. That is where the fireman will shovel coal into the firebox. M.L. Deets photo.
The throttle rod stretches from the stuffing box to the pin hole (circled) of the bellcrank mounted on the throttle body. M.L. Deets photo.
In order to keep the steam in the boiler from leaking into the cab the stuffing box and packing gland are made up of three pieces – the stuffing box, the bronze donut and the packing gland. The stuffing box and donut must seal against the flange in the backhead of the boiler. The cone shape cut into the end of the packing gland must squeeze a relatively soft packing material tightly enough around the throttle rod and into the stuffing box base to keep steam from leaking past.
The stuffing box, bronze donut, and packing gland allow the throttle linkages in the cab to connect to the throttle body inside the boiler. M.L. Deets photo.
Stuffing box flange, located on 1385’s backhead. M.L. Deets photo.
Here is a picture of the old and new operating rods. The old rod had been roughened by rust which would make it impossible to keep the packing around the rod sealed. Lastly, here is a look at how the throttle rod extends through the packing gland and stuffing box reaching for the throttle bellcrank.
A new rod is displayed next to the old rod removed from 1385. M.L. Deets photo.
Demonstration of how the throttle rod extends through the packing gland and stuffing box to reach the throttle bellcrank. M.L. Deets photo.