Stuart Beam Engine in Diorama

[b.lindsey]

Yes but the pillow blocks won't provide much friction 

Bill

[Jasonb]

They are not meant to. The "Friction" is between the O rings stretched around the pully and the rim of the flywheel.

[Noitoen]

From what I understand, he is going to drive the friction wheel to move the flywheel simulating the engine working.

[b.lindsey]

Ah that makes much more sense then. I thought it was to give some "Load" to the engine. My error

Bill

[J.L.]

Right you are gentlemen.

At first, I was thinking that I would have to drill holes right up through the floor of the engine room to bolt the pillow blocks in place. This I did not want to do. Even with a button headed bolt in the floor above, the bolt head would be a detractor.

Epoxying riser blocks in place with studs extending up out of them was next in thought. But in the first photo, you can see that the #4-40 gun tap is cutting a very nice thread in the Corian. No glue necessary.

Jason, you are right; the O-rings will now be arranged to bear against the flywheel rim. However, I want to be able to increase the pressure incrementally unitl it is just right -  and be able to increase the pressure if necessary as the engine wears in the O-rings.

Next will be such a mechanism.

By the way, the o-rings were trimmed in the metal lathe when they were mounted on the pulley to take off the 'slick' and moldng line on the rings and leave a nice, uniform grippy rubber surface.

[J.L.]

The diorama has been lying on her back for the better part of a week while the friction drive system has been designed below.

I wanted to be able to incrementally move the bearing blocks with equal pressure at both blocks - hense the threaded rods bearing against the side of each block.

It should work... We'll see tomorrow. 

[b.lindsey]

Sorry John, but I am still confused. I guess it will become clearer in time as this all comes together.

Bill

[10KPete]

It's too late now but it seems a spring loaded pressure arrangement could work well here. Like a phono turntable drive.

This diorama is just beautiful.

 

Pete

[Jasonb]

Sorry John, but I am still confused. I guess it will become clearer in time as this all comes together.

Bill

Pully with the o rings will be driven by an electric motor. Adjustable bearing blocks mean that it can be moved away from flywheel when running on steam or moved closer to add some load. It can also be used to rotate the flywheel (when the electric motor is running) at a slower speed than the model will run at so it looks more like a large beam engine doing say 20rpm.

[J.L.]

Thanks Jason.  Well explained.
I like your idea of being able to move the pillow blocks forward to engage and withdraw to allow for steam or air propulsion.

In this project, I am only interested in advancing the blocks to engage so there is no mechanism to pull them back. The threaded rods could be considered simply 'push rods'. The threaded rod could be turned back of course, but it would not bring the block with it.

Something to consider if a designer wanted the option of both functions.

Jason, I am rather anxious about the amount of output torque the motor will require to drive the friction shaft. The motor will be directly connected to the friction axle (direct drive).

I will try a gearhead motor today.

Cheers...John

[J.L.]

One issue with operating the engine with an alternative power source will be that oil is not entering the cylinder. With steam and air, it is introcuced automatically.

Although not necessary, this photo shows how oil could be manually introduced into a horizontally mounted cylinder. But with the beam engine, the cylinder is mounted vertically and piping enters the steam chest from the side.

To get oil into the cylinder, I think the only way will be to lift the cylinder cover and manually squirt some oil into the cylinder.

[b.lindsey]

Thanks for the explanation Jason, I got it now. Just wondering though it the pulley with the o-rings on it might need some flanges...thinking the outer o-rings at least may try to work their way off the edge of the pulley.

Bill

[J.L.]

Hi Bill,
Good observation, but the four O-rings are CA glued to the wooden pulley, They are not going anywhere. The circumference of the wooden pulley was coated first, then the O-rings slid on one at a time. When dry, more glue was introduced to the grooves between the rings and allowed to seep down between them bonding them together. As I mentioned, the pulley was then turned on the lathe to tidy things up and give the rings some 'tooth'.

Hi Pete,
Do you still have your turntable? Are you a lover of vinyl as well? 

Your suggestion of a spring operated tension system similar to the friction wheel under the edge of a turntable makes sense, but in this case a lot of force is required to bear against the flywheel - thus the bearing blocks that could be clamped tightly in place.

Edit: Now that I think of it, turntables went to direct drive. That's how the motor will be hooked up to the friction wheel axle.

[J.L.]

The motor...

[Jasonb]

John a lot of early engines had "fat pots" which were like an oil pot that fitted to the cylinder cover for a vertical on on teh cylinder for a horizontal, Animal fat would be placed in them and as the engine warmed up so did the fat until it was liquid enough to be added to the cylinder. Something like that would solve your lubrication issues though an engine will run for a long time on a drop of oil.