bowman bryant valveless

[Anatol]

In my ongoing research into valve solutions in late engines, I've come across the bowman bryant valveless. Quite rare, with a mysterious but potentially amazing solution to the valve problem - one I'd imagined in vague terms. But information, or even images, a tantalizingly rare, as is the engine itself. As I understand it, the piston little end is a ball joint which permits the piston to rotate, back and forth through a small arc, opening inlet and exhaust ports sequentially.
Does anyone here have one or have drawings or can explain inmate detail the mode of operation?
The motor seems to be fast, reliable and efficient. I'm wondering why the idea wasn't copied, or if it was - who did it ...
This engine is really intriguing,
I'm keen to know more
thx!

 

[fcheslop]

Its a fairly simple operation
The piston has two slots milled into in vertically at 180 degrees .These connect to the inlet and exhaust fittings that the cylinders are fitted into as in the engines horizontal frame
The top of the connecting rod has a ball fitting with a pin that fits into a slot in the piston head as the rod rotates around the crank the pin rotates the piston aligning the inlet and exhaust ports .The pin is bent to 30 or 45 degrees from memory
On the original engine you cannot see how they work as the piston is soft soldered together making a chamber for the ball to fit into
I made a single cylinder prototype a few years ago then lost interest.Sandy Cambell helped in its design
To be blunt I dont think the engine is very good lacking power and very greedy for steam more a case of collectors look what Iv got than good engineering but each to there own

 

[Anatol]

Thankyou so much for your quick and helpful reply.

"The piston has two slots milled into in vertically at 180 degrees .These connect to the inlet and exhaust fittings that the cylinders are fitted into as in the engines horizontal frame"

so the exhaust port is ~ BDC (like a uniflow) and inlet is ~ TDC?
so steam and exhaust flow through passages in the piston and enter cylinder via top of piston?

> The top of the connecting rod has a ball fitting with a pin that fits into a slot in the piston head as the rod rotates around the crank the pin rotates the piston aligning the inlet and exhaust ports .The pin is bent to 30 or 45 degrees from memory

I'm still unclear about how the partial rotation and return is caused.

> I made a single cylinder prototype a few years ago then lost interest

I'd like to see it.

> I dont think the engine is very good lacking power and very greedy for steam

do you think it could be 'improved'? Is it a matter of timing or sealing? or temperature, or thermal expansion, or, or...?

The interest for me is that, whatever the problems, you get rid of eccentrics, steam chest and valve gear. (replacing it, of course, with stuff in the cylinder).

 

[fcheslop]

As the crank rotates the pin scribes an arc this rotates the piston. There is no small end its fixed
I had an original engine apart for repair and it was in reasonably good condition with little wear and just seemed lacking in power and greedy for steam .It would rev freely but produced very little torque
Its not a uniflow as both inlet and exhaust are timed through the pistons ports and you can reverse the engine by swapping inlet to exhaust
When I made my single I assembled it and then marked the pistons porting slots through the inlet/exhaust drillings this set the timing
I will see whats left of the engine but as already mentioned you cannot see the pin assy as it is all locked/soldered together
I used a couple of feet of brass making different pistons and rods before hitting on a working design that I believe is how they did it although its a guess and Iv no intention of buying an original at an over inflated price to find out
It maybe possible to improve the design I simply lost interest in it as it didnt fit my need for an engine to fit a boat I was building
Good luck

 

[fcheslop]

This may explain better
Good luck Im sure you will have fun with it
kind regards
frazer

View attachment Rotating+Piston+engine+(Valveless).pdf

 

[Anatol]

"As the crank rotates the pin scribes an arc this rotates the piston. There is no small end its fixed used "

I'm still confused
(Now studying the drawing you sent - thanks!)

"seemed lacking in power and greedy for steam .It would rev freely but produced very little torque"

this is contrary to the remarks on a youtube video. Speaker was very impressed. But then again, no numbers

Do you have any theory about why your version was lacking in power, or how it might be improved?

"Its not a uniflow as both inlet and exhaust are timed through the pistons ports and you can reverse the engine by swapping inlet to exhaust"

I did some drawings. I came up with an idea which does not require rotation. Basically a uniflow, with an inlet port in cylinder wall which opens to a port and passage in the piston, outletting at top of piston, but only when position is (say) + or - 20 degrees of TDC. Do you know if any cases a design like this?

" Iv no intention of buying an original at an over inflated price to find out"

seems reasonable
thanks again

 

[fcheslop]

Iv attached a drawing that shows roughly the amount the piston rotates
The original set up for this engine was for the Luton Bowman boat that only had a simple pot boiler I ran the engine on a 3inc dia vertical with 8 fire tubes using a ceramic gas burner this boiler can run 5/8bore and stroke double acting twin tvr easily and yet the Bowman engine beat it as in the pressure dropped from about 40psi to 25 in very little time
Not very scientific but you could stall the engine with one finger very easily this is not the case with the 5/8 twin
My single was 1/2 bore 3/4 stroke single acting roughly half a Bowman
The Jenkins Bowman toy engines from the 1920s were a far better job as Iv owned both the Sea Eagle and the Luton Sea Jay. The Eagle would steam along very happily
Just my two bobs worth and maybe Iv simply had two faulty engines over the years but I dont think so
Look foreward to seeing some metal been cut on youre project
Good luck

 

[Anatol]

Iv attached a drawing that shows roughly the amount the piston rotates
The original set up for this engine was for the Luton Bowman boat that only had a simple pot boiler I ran the engine on a 3inc dia vertical with 8 fire tubes using a ceramic gas burner this boiler can run 5/8bore and stroke double acting twin tvr easily and yet the Bowman engine beat it as in the pressure dropped from about 40psi to 25 in very little time
Not very scientific but you could stall the engine with one finger very easily this is not the case with the 5/8 twin
My single was 1/2 bore 3/4 stroke single acting roughly half a Bowman
The Jenkins Bowman toy engines from the 1920s were a far better job as Iv owned both the Sea Eagle and the Luton Sea Jay. The Eagle would steam along very happily
Just my two bobs worth and maybe Iv simply had two faulty engines over the years but I dont think so
Look foreward to seeing some metal been cut on youre project
Good luck

Frazer
thanks again.
So great to be ablate learn from folks with such long experience. As noted I got interested in the Bryant/Bowman because of its 'simplicity'.

"I ran the engine on a 3inc dia vertical with 8 fire tubes using a ceramic gas burner"
point taken! The 'engine' is only half the story - or less. Its interesting how little attention people seem to pay to boilers.

"The Jenkins Bowman toy engines from the 1920s were a far better job as Iv owned both the Sea Eagle and the Luton Sea Jay."

The Seahawk was an inverted V oscillator
I saw another called Seahawk with a parallel twin
I can't find pics of the Eagle,
WRT Bowman, I found this website

http://www.brightontoymuseum.co.uk/index/Category:Bowman_Models

- lots of pictures, not much detail

 

[fcheslop]

Sorry my mistake its just Eagle dont know how the sea bit slipped in
Basil harley did some write ups in the model engineer and in his book Toy Shop Steam. He also did some drawings for a repro boat with a different steam plant that to be blunt was a wee bit poor thats the steam plant the boat was OK
This site has some info on the history of the two companies
http://www.bowmancircle.co.uk/page9.php

 

[kno3]

Hello, I have one of these Bowman-Bryant engines, which runs happily, although I just tested it on air. In a new build, i think it would benefit greatly from one or two piston grooves with orings or packing material inside. The original pistons are plain and those are always prone to blow-by.
So if you need any details, let me know. The only thing I didn't do is take the piston apart to see how exactly the ball joint is made, as the assembly is soldered together.

 

[fcheslop]

You may find the O rings and or packing would get damaged by the port slots as it runs
Iv repaired a couple of these engines in the past and like you found the ball and cup soldered together and due to value and the fact they were not my engines I chickened out and left well alone
My single ran as expected just not impressed and think even the simple wobbler a more efficient proposition and probably more durable and less likely to get wet feet
cheers

 

[Buzbey2014]

Very interested in your project ,will be following with great anticipation .

 

[nononick]

I have one of these - found it in the attic of my Dad's house, along with two brass boilers and some pipework with Bowman type threads. I have had it running in an old fibre glass power boat hull. I have never tested its torque, but it drives the boat very well - it doesn't plane but cruises quite comfortably for about ten minutes. I have since joined a club and, not surprisingly, the boilers failed the annual. test. The end plates were full of tiny invisible holes revealing tiny blobs of water under hydraulic pressure, so eventually I will get around to replacing them with similar sized boilers in copper with bronze bushes, maybe adding some water tubes underneath.
I am really grateful for the diagram link showing the ball joint, etc in the piston. I have always been puzzled as to how it worked. It looks as though the inlet and exhaust ports are the same size, so I suppose the thermo dynamics of expanding steam is not being used to best advantage, which may account for the lack of torque mentioned. As a kid I also had some kind of Bowman "speedboat" with an oscillator and of course the nut holding the spring worked loose and it broke down in the middle of the pond. Us adults know the remedy for that, but for kids the Bowman valveless would have been pretty much trouble free, and it did (and still does) the job!

 

[fcheslop]

I think as a novelty and as a bit of a puzzle its a nice wee engine but for me at least once the puzzle was solved at least to my mind the project was completed and I moved on
The engine is supposed to be ported to make use of the steams expansion properties according to its Designer and Basil Harley as mentioned in his book Toy steam? not sure if Iv got the title correct and Basil Harley also did a write up in the Model Engineer or Model Boats
None of the names who wrote up this engine ever explained how it did actually work so that wee drawing by Sandy and my single cylinder engine maybe the only proof of the pudding who knows
im sure someone will know more or better and hope they chime in and build one to prove it
I owned the full set up including the original boat and although it sailed with moderate performance considering the inflated prices they sell for I firmly believe its more bragging rights than good sound engineering
Just my two bobs worth no insults or defamation implied

 

[nononick]

I never tried to look inside my Bowman - apart from anything else I suspected that the top casing of the cylinders would contain ancient asbestos insulation! You may have seen this article (just about legible) by Basil Harley, which mentions there is indeed asbestos inside. I think my dad must have bought my engine and the two brass boilers in the early fifties in the sale when Gamages were selling off old stock after the Bryant firm ceased production, as I never had the boat it was supposed to go in, with copper boiler. I suppose the inflated prices you mention are because the engine seems to have become a collector's piece due to its rarity. I think it was quite cheap at the time.

 

[fcheslop]

I must have been unlucky as my Sea Jay had a simple brass pot boiler
Basil Harley did a reproduction of Sea Jay that was serialised in the Model boats and the drawings are still available I think he called it Sea Jade it was a MAP plan so who ever owns it now will probably still sell them. It is a very good copy and Iv made a couple for collectors who have the engine
The engine and boiler Basil deigned was a flat twin using crank porting the boiler was a twin drum design but seem to remember there was a problem with it
A lot of these old toys contain asbestos like the Stuart Turner ST marine plant that has an asbestos base it was also commonly used for wicks as was lead for pistons and flywheels on many german toys hence the Jenkins Bowman slogan British Toys for British Boys a rather understandable position after the slaughter of the first world war. Elf n safety would have a melt down today small wonder we grew up daft
cheers
frazer

 

[Buzbey2014]

These may be of interest!

 

[Anatol]

Its great to see this thread revived!
Thanks everyone who has posted - most interesting.
Buzbey2014 - are we looking at an original bowman-bryant?

 

[Buzbey2014]

I believe we are , but I can be wrong!

 

[nononick]

You are not wrong - mine looks exactly like that, and I have no reason to think mine is not an original bowman-brant.