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!

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.

 

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.

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.

In our last update, we discussed how the Chicago & North Western #1385 had been converted in 1926 to become a superheated locomotive. One of the components added as part of that 1926 conversion was the superheater header. The superheater header’s job is to take steam from the dry pipe and direct it to the superheater tubes for a second round of heating before the steam is sent to the branch pipes and down to the cylinders.

We now pick up on the repair of the superheater header and its installation.  After the gas weld repairs were finished to mend the broken “T”-slots the header was mounted in SPEC’s large CNC milling machine.  A skin cut on the superheater unit face was made to give an even working surface and then the sealing surface for each of the superheater ball ends was machined. 

The T-slots were also machined to a minimum clearance to accept the new T-bars that will be used to clamp the superheater units into the header for a steam tight seal. 

The original design was to have an individual T-headed bolt for each unit but that concentrates all the clamping stress in the small area of the shoulders of the bolt.  It is believed that is why the sections of the header broke out and had to be repaired in the first place.  The T-bars will distribute the stress along the length of the slot and hopefully preclude any more breaks in the slots. The nuts are extra long so that while the engine is on service the threads of the clamping bolts will be protected from the abrasive blast of cinders flying past and the corrosive nature of the cinders and ash that will collect.

After that operation (and many other tasks) the header was placed in the smokebox prior to mounting it for a test fit.  

Finally, the header is moved into its working position. Looking through a branch pipe hole in the side of the smokebox we can see the freshly machined surface that will seal against the dry pipe as it seats in the flange in the front tubesheet.

The header is gently slid over the studs and when the nuts are tightened it is finally in its home position for the first time on our new boiler. 

A little closer look and a bit of imagination and you can see how the superheater units will be drawn up into the header with the ball ends straddling the T-slots. 

One side of the slot will deliver the steam from the throttle to the superheater unit and the other side will collect the superheated steam for delivery down the branch pipes to the valves and cylinders. 

With the fit-up and sealing proven, tabs are welded to the inside of the smokebox to support the weight of the header while in service.  The sealing surfaces of the branch pipe flanges also get dressed and lapped to seal against the donuts used in the branch pipes.

With the test fitting completed and everything checking out, the header and superheaters have all been installed and are now mated to the header.

A sharp eye will catch a ring of different color between the superheater units and the header.  Due to a discrepancy between the C&NW drawings and how the boiler was actually built we’ve been given an opportunity to improve the sealing surface by adding a heavy brass gasket. 

These collars not only take up the needed space but also give us a brass-on-steel sealing surface rather than steel-on-steel and provides us a replaceable sealing seat for easier maintenance down the line.

All photos provided by M. L. Deets.