Valve porting Saito V4PR

[cfellows]

Just wondered if anyone had an understanding of how the sleeve reversing valve on the Saito V4PR V4 engine works? I'm intrigued with a V4 single acting steam engine, but want it to reverse by redirecting the air.

[ame=http://www.youtube.com/watch?v=1YF7McwbueE]http://www.youtube.com/watch?v=1YF7McwbueE[/ame]

Chuck

 

[gbritnell]

Hi Chuck,
Can't say I've ever had a Saito apart but I would assume there is a ported sleeve that the piston valve slides in that when rotated redirects the air from one part of the valve to the other.
In other words the air comes in to a right angle channel/port which is directed toward the left and right of the valve sleeve. The sleeeve would have a port at each end but naturally at a different radial location. When the valve cylinder is rotated it would open one or the other ports and allow the steam/air to then enter the piston valve chamber where is would be directed to the cylinders.
George

 

[Lakc]

I didnt know Saito had such a rich history.
It appears were looking at the valve mechanism, and since it doesn't change phase, I assume it simply swaps the intake and exhaust port passages. It does look like it runs faster in one direction then the other, which would make sense as the port timing does not appear to change.

 

[fcheslop]

Hi Chuck,The guys on the Model boat mayhem forum maybe able to help I used to have some info but have deleted it but basically if i remember correctly its swapping inlet and exhaust over

hope these are of some help.

best wishes Frazer

 

[dvbydt]

Chuck, found this :-

http://www.flickr.com/photos/69998588@N00/5278233533/

Looks like rotation of the outer cylinder just redirects the flow direction, but it is probably more complicated than that because, if you look at the fixed porting in the other photos, it appears that one of the cylinders in each bank has one hole and the other has two.

Ian

 

[mgbrv8]

Were dose one find plans for one of these?

Dave

 

[cfellows]

Chuck, found this :-

http://www.flickr.com/photos/69998588@N00/5278233533/

Looks like rotation of the outer cylinder just redirects the flow direction, but it is probably more complicated than that because, if you look at the fixed porting in the other photos, it appears that one of the cylinders in each bank has one hole and the other has two.

Ian

Thanks for the link, Ian. I've studied the photos and am beginning to understand how it works. Still have to noodle around with it some to get it to a point where I could reproduce it!

Chuck

 

[cfellows]

Were dose one find plans for one of these?

Dave

Dave, there are no plans available. The Saito V4PR is a commercially built and sold steam engine, not cheap, either!

Chuck

 

[wolfgangbsa]

Did you find out how it work in the meantime? Like this type of engine, but no more in the program from Saito.
My Stuart D10 is almost finished (painting) and need a new project.
Have a Saito Twin and works fine, but Stephenson control.

Wolfgang

 

[Blogwitch]

Chuck,

The valving system really does look like a lash up.

A combination of an overhead piston valve (piston valves are really no more efficient than a wobbler design) with just a basic steam swap over valve. Only the Japanese could come up with such a bodge job.

I'm sure you could get a more versatile V4, even if it is a wobbler, at the least you could get a decent speed control.

Many years ago, I built a nice compact V4 wobbler one that was written up in one of the model boats magazines, mid 80's I think.


John

 

[charlesfitton]

Bogs:

" I built a nice compact V4 wobbler one that was written up in one of the model boats magazines, mid 80's I think."

... are you going to leave us hanging like that?


f

 

[///]

I think the engine Bogs mentions might be the Peter Arnot V4 (also a V2)

www.homemodelenginemachinist.com
www.rcgroups.com
www.ebay.co.uk
madmodder.net (V2)

 

[Blogwitch]

CF,

I'm sorry about that, but my memory is not what it used to be and I just can't remember who it was by.

I have just remembered, Peter Arnot. Mine was given away years ago, but I do have the remnants of one in the back of my shop, given to me by someone who couldn't get it running. There were so many faults and blocked pipes on it, it was a scrapper.

This is a post on here about it.

http://www.homemodelenginemachinist.com/index.php?topic=3755.0

The steam plant that was shown in the mag is here, he gave full details of the boilers as well, both horizontal and vertical.

http://www.rcgroups.com/forums/showthread.php?t=893692

It could be built almost as a true beginners engine as he went into very fine detail about how to make it.

I think, but can't guarantee it, that I still have copies of the plans and writeup in my shop somewhere.


John


/// got in before me.

 

[charlesfitton]

AH! thanks, Bogs- I do remember that engine article.

My error - when I read your post I thought it was one you designed for an article.