Our update of November ’21 covered what was going on with the grate installation inside the firebox. Here we will tie things up and cover the shaker mechanism & linkages. The shaker fulcrums are attached low on the backhead of the boiler near the mud ring. The cardboard over the firedoor hole is a mock-up for a needed spacer to allow mounting the firedoor over the staybolt ends. Detail on why is included below.
The shaker handle is slipped over the short stub controlling the section of grates to be shaken and the latch is released to allow the work to begin. The shaker rods reach under the boiler and connect to the tabs on the bottom of the grates in groups.
Because we are dealing with a new boiler of welded construction modifications are having to be developed and implemented. In the new boiler the welded staybolts stand out from the surface where the original construction used threaded stays which were hammered over during installation and resulted in an almost smooth backhead as seen in this shot from 2004.
A spacer plate has been machined in order to give a smooth mounting surface for the fulcrums and you can also see new pins and latches have been fabricated. In the last shot we can see the grate shaker system fully installed and ready for the first fire.
What are the first three things an operator must know on any boiler? 1) Where’s your water?, 2) Where’s your water?, And 3) Where’s your water?
A steam locomotive’s water level is so important the Federal Railroad Administration includes an entire section dealing with water gauges in the CFR Title 49 Part 230 Steam Locomotive Inspection and Maintenance Standards. Part of 230.51 states that “…The lowest reading of the water glasses shall not be less than 3 inches above the highest part of the crownsheet. …”. What’s the crownsheet? It is the ‘roof’ of the firebox so it will have the heat of the fire on one side and the water of the boiler on the other.
The water is constantly absorbing the heat transferred through the crownsheet and keeping the steel relatively ‘cool’. If the water were allowed to get low enough to let the crownsheet become dry then the heat of the fire from the underside could quickly damage the steel or worse.
How do we prevent this situation? By constantly being aware of the water level in the boiler. But first we must know how low is too low by knowing where the top of the crownsheet is. This was done at SPEC Machine in January by first confirming the engine was setting level. Front to back level was first checked and then side to side.
The next task was to use clear plastic tubing to create a “U” shaped tube open at both ends. One end of the tube was placed against the highest point of the crownsheet inside the firebox but with a small notch in the end to allow air and excess water to escape.
The other end of the tube was brought out through the firedoor and tied to the throttle gland so the outside end would be higher than the end inside the firebox and a funnel was used to fill it with water. Once the water quit running out of the end of tube in the firebox the level of the water shown at the outside end is equal to the level of the bottom or inside/fireside surface of the crownsheet.
To locate the top of the crownsheet and mark it per FRA requirements we had to add the thickness of the welds and the crownsheet itself. Now that we’ve found the top of the crownsheet the water glasses and try cocks can be laid out for installation so the lowest water indication is no less than 3 inches above it. Generally speaking as long as we can see water in the gauges we’ll have at least 3 inches of water over the crownsheet if we’re on level track.
Once finished playing in the water, other layout and installation steps have been made. Locating and installation of the sand dome base has been finished and this task includes another milestone in the 1385 project; the first studs to be applied to the boiler since its delivery to SPEC Machine are used to hold the sand dome base in place. You can even see the glint of one of the new studs at the top of the boiler and just under the edge of the base here.
Another fixture on the backhead is the throttle lever and the pivot point that is studded to the boiler. Here Steve has rigged a temporary way to support the pivot to facilitate this layout. The throttle rod reaches through the packing gland attached to the backhead and through the boiler to connect with the bell crank and levers that will allow the engineer to open and close the throttle which resides in the steam dome.
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.
NOTE: Article may require a subscription to Madison.com to access.
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!
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.