The Wisconsin State Journal writer Barry Adams paid a visit to SPEC Machine to take a look at the latest progress on Mid-Continent’s Chicago & North Western #1385 steam locomotive and interviews shop owner Steve Roudebush.
Progress continues on the grate bearers and grates for the #1385. As seen in the following photos, the center bridge has been completed as well as the Engineer and Firemans’ side outside bearers. As will be shown in a moment the grates will be supported by the round pins on the bearers.
With the grate bearers now installed, efforts turned to the grates themselves. Looking from the Fireman’s side (see Grate Photo 1) almost all the grates have been put in place and are hanging from those pins. On the Engineer’s side one grate has been left out (see Grate Photo 2) to illustrate where the grates hang. It can also be seen how the grates pivot or rock on the pins to allow the crew to clean and manage their fire.
Looking in through the firedoor (see Grate Photo 3) at the left side you can see how the grates form a solid yet perforated floor to hold the fuel yet allow enough air up through the fire bed to promote complete & proper combustion. On the right side the grates are rocked forward to a degree that the fireman would be dumping the fire into the ashpan. This is done in the morning while cleaning the fire of yesterday’s ash while preparing for today’s fresh fire and another day of steaming. If the fireman simply needs to even out the fire or shake down some accumulated ash the grates can be rattled back and forth just a small amount. This will cause the ash to fall down into the ashpan through the holes in the grates.
You can see in the photos we are using “experienced” grates. A few are bowed due to poor ashpan management causing excessive heat and causing the grates to warp. Here is a more detailed shot (Grate Photo 4) of the open grates and the large “dump grate” at the bottom of the photo.
The dump grate (Grate Photo 5) is closest to the firedoor and is about the size of two of the other grates. It pivots not in the center but along the edge closest to the firedoor and as the name implies is used to dump a large amount of either ash or fire as needed into the ashpan.
The grates are divided into three sections looking back to front in the firebox and there is the fireman’s set and the engineer’s set. The large tabs that extend down from the bottom of each grate are connected by a series of tie bars, pins and levers to the grate shaker fulcrums in the cab.
At the time the photos were taken, the shaker arrangement was being laid out on the floor for evaluation of the extent of needed repair/replacement of parts. The shaker fulcrums and latches will be mounted to the boiler and some of the other parts will get mounted to the rear boiler support which has also been newly installed.
Bit by bit the puzzle pieces are finding their way back together to form a living, breathing iron horse and soon #1385 will again be the Whistle on the Wind!
Branch Pipes Follow-Up
In our January 2021 Update, it was discussed that one of the upcoming tasks was to create “donuts” to insert between the branch pipe and steam chest and between the branch pipe and superheater header. That task has now been completed.
These spacer donuts are needed to adjust for minor manufacturing size differences and space variations between the new and old components. The donuts needed to each be custom made to be steam tight and to properly position on both ends of the branch pipes.
Reconstructing the Grate Bearers
If you have a home fireplace, you know that you don’t place logs directly onto the floor of the fireplace when burning. For better combustion, the logs are usually placed on a metal grate which props the logs up and allows air to more easily flow underneath the logs and helps feed the fire with more oxygen, allowing it to burn hotter. This same concept applies when firing a steam locomotive – the grates on a locomotive are just larger and more complex, allowing the fire to be manipulated by the locomotive’s fireman.
The grates are rectangular cast iron pieces with many holes through them that form the floor of the firebox. That cast iron floor holds the coal as it burns so the locomotive can generate the heat needed to boil the water for steam.
As you look in from the firedoor there are two rows of grates that run from the front of the firebox to the back. Each row of grates is about half the width of the firebox so the dividing line (front to back) is the centerline of the firebox
The grates are set on – and held in place by – the grate bearers. The grate bearers were originally cast iron brackets with a row of pegs to hold the end of each grate. There is a row of pegs that runs down each side of the firebox, front-to-back, and then in the center there is a bridge that runs front-to-back with pegs on each side to hold the inside end of both rows of grates.
In the mid-1920s the grates were somewhat redesigned and in the later 1920s the Chicago & North Western’s repair procedures documented on the drawings said to weld the new pieces in place. During this locomotive rebuild, Mid-Continent is doing the C&NW one better and is making the new bearers an all-welded assembly. As can be seen in the photos the old bearers have been eaten away by the very corrosive nature of the ash and repaired by weld.
In these photos, the web portion of the new side bearers have been machined and are ready to accept the pegs that will be welded in place to hold the grates and lay beside the originals they will replace.
The old center support is not in horrible shape but has been modified and repaired over the years. The main web of the new center support has been tacked together to allow for fitting into the firebox. Once it had been trimmed to the proper length and height the pegs will be welded in, a plate along the bottom edge will be welded on and the bridge support pieces will be added to make a complete assembly.
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.
- 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.
- 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.
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.
- 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.
- 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.