Tripple B Beam engine

Does anyone have any experience of this beam engine.

I have some drawings which I found on the internet, however they are not very good, I have started to re-draught the plans and there are a number of errors and omissions which I have found.

Initially this was a Turbocad learning exercise, but I may build it when I am back on my feet.

Sorry, no knowledge of it … but

The first response from a Google search was :

“ Did you mean: Triple B Beam engine “

MichaelG.

If you are using the drawings by Julius then worth redrawing it to make sure the assemblies move and that there has been no fudging of hole & pin sizes to get round linkage geometry that locks up.

Jason,

Julius? Would that be J.A.M. DeWaal in NZ?

If so those are the drawings I am re-draughting. It started out as a learning project for Turbocad whilst I am laid up. I have already discovered the errors in the linkage geometry and have got the tracking error of the top of the piston rod to >0.1 mm

I have also noticed that the link rods are shown as being pinned together on one of the shafts, this will stop the links rotating independently and the bushing arrangement is not satisfactory.

Edited By Marcel Jolinon on 12/01/2023 11:10:12

That was supposed to read less than < so the deviation from vertical is < 0.1mm and that is at the extremity of travel.

And the diagram was supposed to be moving. It was generated by GeoGebra, a maths tool which is really good, but took some working out.

That's the guy.

I'm not sure where the original was published but may be worth trying to track that dow.

I have spent some time trying to track down the originals, apparently a design by Bob Holme, but not found anything yet.

I just twigged who designed it, I'm not used to his real name. You can download the original drawings for "Bobs Barstock Beam" from the attachments in this thread on MEM forum - just need to join to be able to access the attachments

Now that is intereting. JDW appears to have scaled the drawings up by a factor of nearly 1.5:1 but seems to have done some rounding on the conversion. I think this may be the reason the Watts Link is out of kilter and does ot follow a perpendicular path, but I may be wrong.

Having read the thread in the above link, and I have no idea why my searches didn't show that website, it would appear that those who have built the engine have not encountered problems with the linkage jamming up.

This has prompted me to look further into the linkage for the valve timing, currntly getting stuck with the moddeling.

More to follow.

Edited By Marcel Jolinon on 19/01/2023 19:23:19

A lot of Julius' drawings are larger than the original and as you say often some rounding up or down is done and that can be compounded if it was originally an imperial design converted to his preferred metric.

I have entered the dimensions in to GeoGebra and created an animation of the motion. Given the published dimensions the piston will hit the lower cylinder head and the Watts linkage is out of alignment and the piston rod will bind.

I have been over the numbers several times, and have now begun to question my drawings

What started out as a drawing to get to grips with Turbocad has taken on a whole new dimension. I would be interestd to know if anyone has tried to build that engine from those drawings.

It is a pitty I can't post the GeoGebra files on here, I think some may find the excercise of interest and I also thing there is some use for this app. If anyone wants to have a look at the workings I can email them.