Does anyone have access to drawings for a regulator mounted on the firebox wrapper instead of the backhead? I believe I've seen this type of design before, in which its a quadrant regulator, but it's pivot point turns a shaft passing through a flange in the boiler shell, which in turn is attached to an arm and the rest of the normal linkage system. I believe this would also imply that the notched teeth that give throttle positions would be fix mounted to the boiler, and not to the regulator arm as in the standard design.

Preferably looking for a Baldwin variant of the design, but honestly anything will do.

I have a lot of experience with a Baldwin with the throttle lever and quadrant on the top of the wrapper in the cab and the rod running through the front wall of the cab into a gland on the steam dome. Is this what you want to know about?

Hey Dave,

Thats the design I'm trying to avoid. The locomotive as designed has that and is a saddle tanker. I can imagine that if the packing gland starts to leak, it creates quite a mess and is very difficult to correct without pulling a lot apart.

That being said, if you have details and experience about what its like to maintain and operate with that design, I'd love to hear it!

In rereading your first post, you mention the throttle rod turning - US practice is to have the rod go in and out reciprocally through the gland rather than rotate within it, so I'm thinking about a Euro - centric variant like the British rotating rod but with a quadrant perhaps to hold it at the point to which you have rotated it? Probably the wear would be very different in a rotary rather than reciprocal situation. I don't recall much need for tightening or repacking once the packings were installed and worked in to fit, by the way, but burying anything that needs to be maintained under a saddle tank seems like a Very Bad Idea to me. The process of working it in and getting it adjusted would be orders of magnitude more difficult, for example. I'm wondering of a modern metallic design with a spring loaded follower so you eliminate the need to tighten might be a better way to go? The quadrants on our Baldwins were attached to the throttle lever itself rather than being separate, and floated with it. The angle between the quadrant and lever changed as it was pulled or pushed - the rod that went into the dome was attached to the casting that also held the quadrant which maintained it's longiitude. The latch held it at a set angle. I know, it's confusing...…. I wish I had a photo handy.

Quite a few of the smaller Vulcan Iron Works saddle tankers had the throttle lever on the top of the firebox, with a bell crank inside between the wrapper and the crown sheet with a rod going forward above the crown sheet to another crank attached to the throttle itself.

The trick is to mount packing gland on an extended pipe from the dome, so that the packing gland itself is in the cab.

Porter also used the top mount as described with a packing gland in the wrapper sheet. I don't have any Porter drawings but others may be willing to share......mld

Another version has the packing gland within the cab. The throttle rod runs through a pipe which is threaded into the back of the steam dome. The pipe is actually under boiler pressure and the rod runs through it. The gland is easy to get to inside the cab.

...which I just realized it what Kelly was describing.

Great minds think alike.

Well it sounds like I have two options to go on from here, going to need to talk to the higher ups now to see what potential thoughts they might have on the choice.

Anyone have photos or drawings of the Vulcan/Porter design they'd be willing to share?

Kelly, I would imagine that the pipe would definitely need some kind of rigid bracket thats mounted to the boiler near the cab wall to prevent the pipe from vibrating around and creating a stress crack over time..? It definitely does sound like it offers an improvement over the original design by having the gland somewhere accessible!

Whats the opinion on space in a 34" dia boiler. Is the space saved by locating the linkage rod outside of the steam space worth it, or is the boiler already too small for it to be noticeable?

Thanks for the help so far

Stewi - are you building a new boiler or replica locomotive or restoring something? A new build might offer more flexibility in design.

Another version I had seen/used is where the throttle lever mounts to a rod that goes down into the top of the boiler, This rod has a crank inside the boiler the transmits the rotary motion to a longitudinal motion. A rod on the crank goes forward to the throttle valve in the steam dome. The packing gland is located where the rotating rod (to which the throttle lever is attached) comes out of the boiler.

I've seen/ used this arrangement on former WSLCo Heisler #2 at Roaring Camp as well as on Rotary snowplow OY on the C&TS.

Hey Dave,
The throttle would be placed on a new boiler for a new build, hence my eagerness to shop around for a different option than the original design! Whether or not we actually get to the stage of construction, I can't be sure, but I'd likely give it about a 60%-70% chance in reality. The "set in stone" objective of the project however, is to show off the ability of the young engineering members of our organization, as we've been assigned with the task. It also allows us to show off a project that our "in the works" new restoration shop could actually (and hopefully will) build, sans boiler sheet forming. viewtopic.php?f=1&t=39331&p=247385#p247385

Hey Earl,
Looks like you've Struck again! Wasn't aware that Heisler used the design as well, so that adds on to the previously mentioned Porter and Vulcan.

The bell crank over the firebox method would require enough space between staybolts or crown bars, depending on the design. If the drypipe for the turret runs from the dome down and back, it needs to fit in there too. Vulcan iron Works built some 5 coupled engines for Turkey that had the drypipe for the turret run outside of the boiler inside a casing which could free up more space over the crown for throttle linkage, but also would need to dodge the tank. The throttle rod isn't too large if you want to run it through the backhead leaving the top of the wrapper sheet for the drypipe and turret, might be an easier fit. Or, you could build with wet superheaters and a front end throttle, and run the appliances on superheated steam - since it's a new build, you have options. Young engineers might like to show off efficiencies like a GPCS firebox as well....... Have some fun with it.

Bracketing a avoid vibration is always a good idea.

With a boiler that small, access for assembly work of the throttle linkage (or anything else) requiring someone to be inside the boiler will be impossible. Put everything outside the boiler that you can.