32: penberthy

This update focuses on the Penberthy appliances: the injector and the boiler sight glass (sometimes shorthanded as “waterglass”).

The injector is a fairly important part of the locomotive. It allows the crew to add water to the boiler. Now, since the water in the boiler is pressurized (125 psi, or 8.5 atm gage), and the water in the tender is at a cool 1 atm, it requires work to put 1 atm water from the tender to the 8.5 atm boiler. In the 1800’s, the crew used to have a hand pump, and that gets tiresome quickly. The period that the CK Holliday represents had a crosshead driven pump, but that only works when the crosshead is in motion–that is, when the engine is moving.

So, the injector was invented to literally inject the water into the pressurized boiler. It works by combining steam and water in a chamber, and shoots this water/steam mixture out of its outlet. This is a very simplified explanation, and of course there is a lot going on inside this “mixing” chamber.

Here’s how the injector is laid out on the CK Holliday.

The above is the right-hand injector (engineer’s side). There are two injectors, one on each side (not shown). Generally, only the fireman operates the injector (left side), so the plumbing you see above will mostly go unused!

The water supply comes from the tender. It’s plumbed under the running board and up into the injector. The boiler feed water pipe also runs similarly under the running board, which goes to a check valve so that the boiler’s internal pressure does not release its water out the feed pipe. The injector overcomes the boiler’s internal pressure by about 50 psi. Update: Steve D at Burnsland corrected me. The overcoming pressure from the injector is actually about 8 psi.

The water sight glass, also by Penberthy, is a simple device that allows the crew to visually monitor the boiler’s water level. Its plumbing is made to simply allow the water in the boiler to rise up the waterglass. Reading the glass takes some experience, as the water will not necessarily read to its true level while the engine is in motion.

Plumbing is quite a tedious process!

31: backhead plumbing and progress shots

The backhead is being fitted with valves, gauges, pipes, and levers.

The two gauges are Ashcroft boiler pressure gauge and duplex air brake gauge. The “U” shaped pipes to the left and right will feed the steam to the left and right injectors. The top three red valve wheels will feed the blower, air pump, and atomizer respectively. And the large red wheel just below and behind the air brake gauge is the main header valve.

All the steam appliances will be supplied from the steam manifold behind the boiler gauge. It’s the large, short cylindrical pipe in the picture above.

On the back of the boiler, the red valve with four spokes is part of the water glass piping. To its right is the throttle. The oval hole below that is a boiler washout. The two diagonal red valves are the dual cocks, and finally the vertical bar is the reversing bar.

The throttle is locked in place by a quadrant with teeth. It operates much like the reversing bar, using a latch-spring type mechanism. Its operation is quite interesting as the quadrant moves with the throttle when operated. I’ll post a video of this up later.

And now, just some overall shots of the progress:

30: valves

The CK Holliday uses several different types of valves. I’ve made the first two types to use on the model:

The main header valve is a 2″ model. It’s mounted on top of the boiler and allows steam to be supplied to the appliances in the cab.

The dual-cocks are 0.5in type. Note the funnel at the bottom that allow steam or water to exit.

Both valves were made per Lukenheimer’s specs. However, these valves get replaced time to time, so the type that you’ll see in person or in pictures will differ slightly. I am modeling the valves as they would typically appear.

29: boiler touchups

The Fullerton RR day last weekend was a lot of fun, and I even learned a thing or two!

DLR did not bring out an engine to show this year, but they had the Lilly Belle the coach and the display boiler–the same boiler that is kept in the roundhouse as a learning tool:

Now it has been painted to make identifying parts of the boiler easier. Here are some pictures from Saturday:

I felt triumphal in finding that almost everything I modeled is correct to the real counterpart. There were some parts that needed changing, mainly:

  • Change flues from 2″ OD to 1″ OD
  • Change the t-pipe from welded to bolted connection
  • Change number of stay bolts across the boiler
  • Add tube sheet bracing above the firebox

And I finally have access to the ashpan.

My updated model is below:

The ashpan has a narrow grate at the bottom to allow embers to be cleared out and air to flow in. There’s also a 12″ access panel bolted to the bottom.

The sand dome base, made of cast iron, is attached to the boiler below. It’s held in position by 2 1″ bolts welded to the boiler.