Monthly Archives: July 2012

40: cylinder and steam chest decorative covering and pilot

Time to dress up the cylinders and steam chests. The brownish outline below shows how the cylinder and steam chest gets “wrapped” in brass and other cover.

The decorative covering consists of a cylinder jacket, cylinder brass cap at the front, the brass cap at the rear (2 halves), the saddle side cover, the steam chest brass box, and the steam chest cover. There’s a hole at the front of the steam chest–this is for the relief valve that will be installed later.

And as promised, here’s a closeup of the pilot:

As straightforward as it can be. There’s some internal framing, as well as tension rods mounted to the top of the bumper beam. The rods keep the pilot from drooping under its own weight.

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39: motion studies

Here are some of the motion simulations that are possible in the computer.

The first one is an extension of the eccentric motion I posted a while back. This time, the main and side rods have been put in place and the crossheads (and the hidden pistons) are now in motion.

Some notes to observe:

  • The motion simulates the engine running at about 2.5mph
  • The offset of the two pistons is more obvious when watching the two crossheads move relative to each other
  • The tendency for the lifting shaft, link, and the reverser bar (out of view) to nudge or swing “forward” as the wheels spin. This is why the reverser bar arc is notched. In the animation watch the lifting shaft carefully for this effect
  • The mechanical lubricator link can be seen in the upper half of the animation. It’s driven off the left valve stem
  • The empty slots at the crosshead/piston rod junction will receive the piston/crosshead key

Next simulation is the throttle valve linkage. The throttle bar (left) is linked to a valve at the top of the dry pipe (L-shaped rising pipe, right). The valve is inside this pipe and when the throttle is closed, the valve sits snug in a seat in the dry pipe. When the throttle bar is pulled, the linkage causes the valve to “pop” open and allows steam in the steam dome to enter the dry pipe, then onto each cylinder and piston.

The yellow vertical pipe immediate behind (left) of the dry pipe is the header pipe, which takes steam from the steamdome into the cab to run appliances.

And speaking of throttle, the next animation shows the throttle quadrant in action. The quadrant is notched, and a spring-loaded block with teeth “grabs” the notches to hold the throttle in place against the steam pressure acting on the throttle valve.

It all looks simple, but there are a number of subtle movements, such as the moving quadrant and the pivot of the throttle bar.

Note that to actually move the throttle, the engineer would grab the handle at the end to release the spring-loaded latching block from the quadrant. That action is not in the animation. The latching block simply slides along the edge of the quadrant instead. I used this motion to ensure that the latching block is concentric to the quadrant.

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38: plumbing checklist

The engine’s plumbing is (almost) finished! This was, by far, the most head-scratching induced phase of the model.

Here’s a checklist of what’s done:

  • Dry pipe
  • Header
  • Steam gauge supply
  • Blower
  • Air compressor steam supply
  • Atomizer (steam)
  • Hydrostatic lubricator, steam in
  • Hydrostatic lubricator, oil out
  • Boiler water sight glass, supply and return
  • Boiler water sight glass, drain
  • Left injector: water feed from tender, steam supply, and overflow
  • Right injector: water feed from tender, steam supply, and overflow
  • Left and right injecting water feed to boiler
  • Dual try-cocks
  • Air compressor exhaust
  • Air compressor compressed air line to air tank
  • Air compressor governor line
  • Air line from tank to brake stand
  • Air line from equalizing tank to brake stand
  • Air line from brake stand to left and right brake cylinders
  • Air line from brake stand to duplex gauge, black pointer
  • Air line from brake stand to duplex gauge, red pointer
  • Air tank condensate drain
  • Atomizer (oil)
  • Air line from brake stand to tender
  • Blowdown (water)
  • Blowdown (air line)
  • Mechanical lubricator feed line left and right

Not completed:

  • Compressed air umbilical hookup
  • Try-cock funnel
  • Equalizing tank condensate drain

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engine drawings

Just for fun, let’s look at the engine from line drawing perspective this time.

I added the pilot (cow-catcher), smokebox braces, and the deck, so that the engine now look fairly complete. Lots of other details were added since the last update, too, such as the cylinder cocks and the associated linkage, which are of course “operable”.

Here’s the right side:

Just looking at it: there’s no mistake that it’s not the Lilly Belle, or any other 4-4-0s, it’s indeed the CK Holliday. It’s the overscaled cab, the balloon stack, the long pilot, and 1000 other details that help shape the whole engine.

The smokebox braces were interesting because they actually curve inward at the front. You can see this effect in the front view:

More details on the pilot’s construction to come…

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37: mechanical lubricator

I couldn’t find the manufacturer’s name of the mechanical lubricator used on the DRR, so I made a “typical” version of the device.

The mechanical lubricator is so called because it uses mechanical crank and cam to force the oil into the system needing lubrication, in this case, the two cylinders, containing the valves and pistons. The other type of lubricator is the hydrostatic, which uses the steam to carry the oil.

The twins on the Disneyland Railroad aren’t “supposed” to have mechanical lubricator. On the Holliday, one can see false oil cups mounted on top each cylinder. On both engines, the mechanical lubricator is mounted on the left (non-park) side of the engine. To even further hide this device, the lubrication tubes are hidden under the boiler jacket when possible, or otherwise tucked away into the shadow of the running board. In fact, they’re so well hidden that these tubes are quite difficult to trace from photographs–I had to use some imagination to route these tubes realistically.

Below are some of the parts of the lubricator, and how they fit on the engine:

The terminal end of the tubes at the steam chests will be hidden under the steam chest covers.

Each time the valve rod moves back or forth, that is, when the engine is in motion, the “Motion Link”, annotated above, moves a small crank on the interior side of the engine. Each time it cranks, a small amount of oil is ejected into the cylinders.

Here’s a video from YouTube demonstrating the action. The cover is open so you can see the cam working inside. Note also that the crank arm is driven by an eccentric instead of the valve stem.


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36: engine’s cab, continued

The wooden engine’s cab is done. It’s detailed with panels, moldings, glass windows, and roof planking. The picture below is the cab in natural wood (and I think I prefer it this way to the red paint).

Above, note the operable sliding window on the rear side of the cab. Note also that the two small windows at the rear wall of the cab are without glass.

The interior picture shows the individual roof planking, and the front window hinges.

The original cab did not have the roof hatch that can be seen today.

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