Steam Fire Pumper 1869

[J.L.]

Never thought of that! Saw horses...

Hi Tom,
Well with lock-downs and self isolation, it could be awhile.

There are many small parts to be painted red, copper or gold on this model. I have always had a tendancy to rush painted parts and touch them before they have really hardened.

With this project, you can switch gears and focus on other parts to let them dry properly.

So wheels will be the down-time.
 

[J.L.]

Ken Foran also designed a buckboard model for Trailways. But with that build, a wooden template was provided with a hole in the middle to accommodate the hub. The spokes were 'dished' to the rim by having the hub set on waxed paper higher than the rim. I was told that dishing a wagon wheel was done to distribute heavy loads on the wheels.

But this is not the case with the steam pumper wagon. The spokes are in-line with the rim. You would wonder with all that weight onboard. I must be missing something here.

Also the paper template provided with the model was not of the correct diameter. You can see the error in the photo above. I put it in the printer and photocopied it at a 94% reduction. Then little marks were made on the laser cut rim at each spoke location.

A wooden base with a recessed hole allowed the spokes to rest in line with the rim.

[Elam Works]

My understanding of dished wheels was it allowed two things.

As the rim was shrunk on, it would suck the fellows and the spokes in tight to the hub. Once they became end bound having the iron rim pull it tighter to more or less dish provided a bit of a safety valve if you did not get your shrinkage measurements just right.

More importantly the dish was there to keep the load off the wheel bearing nut. Or in the case of more primitive examples, the washer and pin. The conical ends of the axle were bent downward, so the bottom profile of the stub axle was parallel to the ground. The wheels were canted outward. The dish matched the angle of the axles, so that on the lower portion of the wheel the load past directly vertical up the spokes to the hub. This did not generate any axial load. The upper portion of the wheel was canted outward due to the dish, which gave a bonus of extra clearance with the body. If the cone of the stub axle were horizontal, the weight of the carriage would constantly try to force the wheels out and off the ends of the axle, putting extra load on whatever retained the wheel on the bearing.

At some point I suppose with a very heavy artillery type wheel, dish became impractical or of little value. Also with Savin patent iron hubs with ball or roller bearings, the retaining nut became substantial enough that having it under axial load all the time (as in autos) was not so much of a issue anymore. There may have been geometry reason that they wanted to keep the axle spindles horizontal as speeds increased and the design modernized. Not that a horse drawn steam pumper is going to break the speed limit, but horse drawn and early autos were cross-sharing a lot of chassis development ideas.

-Doug

[J.L.]

Took the law into my own hands and deviated from the suggested method of assembling the spokes in the book.

I was getting nowhere without the rim fixed firmly in place. Three escutcheon pins now hold it down to the board.

Each spoke can now be custom fit between the hub recess and the rim.

I forgot to put the waxed paper back under the assembly and will do that before proceeding further. CA glue will be used to glue things up.

Note: The rim may not be perfectly concentric to the hub - but it's close to the template lines. That's why I reduced the template to 94%. If it's not, a man on a galloping horse may never notice. The wheels won't be going anywhere.

[J.L.]

Thanks Doug. Well explained.

[Elam Works]

Not high resolution, but I think this illustration shows the principle.

-Doug

[gbritnell]

Nice work on the wheels Doug!
I had built a model of a Gatling gun (non firing) from patent drawings I got from the library. The drawings showed the wheels with the canted spokes just like you built. I made them the same way never actually knowing why.
gbritnell

[Don1966]

Love the wheel work John I have a stage coach that has wheel work to do on it. Taking notice of your work. By the way your hobby matte looks like mine used....


 
Don

[J.L.]

Hi Fellows,

Thanks for the nice comments. Wheel making seems to be a topic here. Fear not, engine making is going on in the background as we dicusss wheels.

You can see the dished spokes on the spare wheel mounted on the caisson in photo one.

An added detail for wheels can be bolt heads betwen each of the fellows. The mill is set up to center the wheel for each hole. Brass escutcheon pins will be used.

[tghs]

i like your method so well I stole it and have a piece of mdf recessed for the wheel hub to go home with me today..

[J.L.]

I think recessing the hub will work for you.  The upgrade kits that replace white metal wheels with wooden ones come with a jig that has a hole in the middle.

Here are the front wheels primed. I would not have thought of priming the wheels before shaping the spokes or the inside of the rims. But the designer of the kit suggested that by doing that, you can clearly see pencil lines or the amount of material being carved away.

While the primer dries, work continues with the frame and its first assembly - the bottom of the steam box with its manifold.

[Flyboy Jim]

My understanding of dished wheels was it allowed two things.

As the rim was shrunk on, it would suck the fellows and the spokes in tight to the hub. Once they became end bound having the iron rim pull it tighter to more or less dish provided a bit of a safety valve if you did not get your shrinkage measurements just right.

More importantly the dish was there to keep the load off the wheel bearing nut. Or in the case of more primitive examples, the washer and pin. The conical ends of the axle were bent downward, so the bottom profile of the stub axle was parallel to the ground. The wheels were canted outward. The dish matched the angle of the axles, so that on the lower portion of the wheel the load past directly vertical up the spokes to the hub. This did not generate any axial load. The upper portion of the wheel was canted outward due to the dish, which gave a bonus of extra clearance with the body. If the cone of the stub axle were horizontal, the weight of the carriage would constantly try to force the wheels out and off the ends of the axle, putting extra load on whatever retained the wheel on the bearing.

At some point I suppose with a very heavy artillery type wheel, dish became impractical or of little value. Also with Savin patent iron hubs with ball or roller bearings, the retaining nut became substantial enough that having it under axial load all the time (as in autos) was not so much of a issue anymore. There may have been geometry reason that they wanted to keep the axle spindles horizontal as speeds increased and the design modernized. Not that a horse drawn steam pumper is going to break the speed limit, but horse drawn and early autos were cross-sharing a lot of chassis development ideas.

-Doug

Great explanation Doug. Took two times reading through to get it.  The follow up diagram helped a lot as well.

Jim

[J.L.]

Here are the parts of the engine that do the work. You can see the serpentine flywheels, the double crankshaft and the slides with their lubricators.

I have no idea how this engine operates. 

I would imagine the pushrods would cause water to be sucked into the watr box, then driven out into the hoses. Maybe when I put everything together I'll have a greater idea of what is going on. 

[zeeprogrammer]

You're really moving along. I'm loving the pictures. Well done!

[J.L.]

Thank you Carl.

Quite a bit of time was spent crawling around the floor looking for some of these small parts conneccting the crank to its slides.

Close examination would reveal a lot of little errors in this section of the model. But from a viewing distance, things are going to be okay.

I noticed yesterday, that the kit was missing a key element for the front axle - a circular oil pan that sits on its frame. I think I can turn one on the lathe.

P.S. That manifold top needs another coat of paint.