Author Topic: Southworth 6" Boiler Feed Pump  (Read 1545 times)

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 582
Southworth 6" Boiler Feed Pump
« on: February 06, 2019, 07:04:10 PM »
I started building this pump three weeks ago and completed it yesterday, There are no pictures for a build log because I could hardly see many of the operations let alone photograph them as the parts were virtually obscured by the milling chucks or hidden in vices.
I bought the kit / castings at the Bristol Show last year. It isn't difficult as long as you plan ahead about how you're going to hold some of the small components and take great care tapping 10BA threads!
I found it difficult to get it to run at first, probably because the shuttle valve stuck repeatedly and the screw securing the pilot valve drive (slide valve) kept slipping . This meant that I had to repeatedly undo the eight 8BA nuts securing the valve chest cover, I lost several as I fumbled putting them back on.
I'll run the pump to bed it in then take it apart for the cosmetic work.
I am very pleased with the results, the pump seems capable and I look forward to using it with my 6" vertical coal fired boiler.

Here are some pictures of the pump and a YouTube video of it working on compressed air'



Andy
« Last Edit: February 06, 2019, 07:07:24 PM by Chipmaster »

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12552
  • Hampshire, england.
Re: Southworth 6" Boiler Feed Pump
« Reply #1 on: February 06, 2019, 07:31:58 PM »
 8) Nice little pump Andy,

Jo
Usus est optimum magister

Offline Admiral_dk

  • Full Member
  • ****
  • Posts: 1365
  • S°ften - Denmark
Re: Southworth 6" Boiler Feed Pump
« Reply #2 on: February 06, 2019, 09:18:51 PM »
That is small and it works as requested => time to celebrate  :cheers:

Offline scc

  • Full Member
  • ****
  • Posts: 554
  • Lancashire, UK
Re: Southworth 6" Boiler Feed Pump
« Reply #3 on: February 06, 2019, 09:23:29 PM »
Lovely :ThumbsUp:    Re-kindled fond memories of  playing with (bigger!) Weir pumps during apprentice days.         Terry

Offline Gas_mantle

  • Full Member
  • ****
  • Posts: 1333
  • North Yorks - UK.
    • My Youtube channel
Re: Southworth 6" Boiler Feed Pump
« Reply #4 on: February 06, 2019, 09:33:36 PM »
Great stuff Andy, looks to be a good runner and pumps at a decent rate.

I have the castings for the 3" version that I haven't started yet but I now know where to come for help  ;)

Offline 10KPete

  • Full Member
  • ****
  • Posts: 1560
  • Nordland, WA, USA
Re: Southworth 6" Boiler Feed Pump
« Reply #5 on: February 06, 2019, 11:39:12 PM »
That's a very nice little pump!

I've never actually seen one in person so I need to ask about the steam valving. There is a  standard sort of slide valve  I think but then folks mention a shuttle valve also, so I would guess that the slide valve isn't directly operated by the piston rod attachment.

Is there a drawing detail that would show the valving?

Thanks,
Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12552
  • Hampshire, england.
Re: Southworth 6" Boiler Feed Pump
« Reply #6 on: February 07, 2019, 08:31:59 AM »
This is the GA of the 6" Pump

The castings for this pump are now available, with all the other Southworth Engines, from Blackgates at a very reasonable price  :)

Jo
Usus est optimum magister

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 582
Re: Southworth 6" Boiler Feed Pump
« Reply #7 on: February 07, 2019, 10:33:20 AM »
Hi Pete & Jo,

Here is a link to a video of an identical pump with a transparent valve chest cover to show the shuttle valve in action.


I'll have a look at the plans to see if I can adapt them to show the ports and connecting passages clearly.

Andy

Offline crueby

  • Full Member
  • *****
  • Posts: 8799
  • Rochester NY
Re: Southworth 6" Boiler Feed Pump
« Reply #8 on: February 07, 2019, 02:06:29 PM »
Thats quite an action, fun to watch but I don't understand how it works at all.  Any further diagrams most appreciated here too!




Offline 10KPete

  • Full Member
  • ****
  • Posts: 1560
  • Nordland, WA, USA
Re: Southworth 6" Boiler Feed Pump
« Reply #9 on: February 07, 2019, 08:36:45 PM »
Jo and Andy, thanks for the drawing and video. Like Chris, that helps some but more detail is needed to help sort this out in my mind. There is some porting and other things that are as yet mysterious... :thinking:

Google hasn't helped...

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Admiral_dk

  • Full Member
  • ****
  • Posts: 1365
  • S°ften - Denmark
Re: Southworth 6" Boiler Feed Pump
« Reply #10 on: February 07, 2019, 08:54:34 PM »
As far as I can tell from the "drawing" - the piston rod is connected to the "balance arm" (used to invert the movement). The other end of said arm moves up and down the valve rod, without doing anything until just before the end of the stroke, where it hits one of the "stoppers" on the rod. This forces the rod to quickly move the valve to the opposite position - swapping the "exhaust for the inlet & vice versa". Everything now moves the opposite way, until the arm hit the "stopper" on the other end of the valve rod.

I hope this clarifies things - if not please tell me what I got wrong.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 582
Re: Southworth 6" Boiler Feed Pump
« Reply #11 on: February 08, 2019, 11:37:56 AM »
I can't find a good visual explanation of how the shuttle valve works so have a go at interpreting this plan of the steam cylinder and valve chest which I have copied and also pasted in the Shuttle valve and Shuttle from other parts of the plans

The Shuttle valve and shuttle  (items 15 and 16) slide up and down in the left hand side of the valve chest (Item 2). moved by steam controlled by the Pilot valve which is moved by the the piston rod via the "balance arm" used to invert the movement - thanks Admiral_dk  :).

Someone with time on their hands who can create these computer simulations could probably produce a visual aid for this. If a member can add a link to an appropriate video please do.
 
When I built the model I blew up the plans to help understand where the 1/16" diameter steam passages were to go and how they connected  :headscratch:. The Steam Cylinder plan is helpfully annotated with an  order of operations that should ensure success.

Andy
« Last Edit: February 08, 2019, 01:04:18 PM by Chipmaster »

Offline crueby

  • Full Member
  • *****
  • Posts: 8799
  • Rochester NY
Re: Southworth 6" Boiler Feed Pump
« Reply #12 on: February 09, 2019, 02:04:08 PM »
I've got it sussed out! Did some drawing in Fusion, and it makes sense to me now. I did not use the plan that Chipmaster put up, but instead the plans for the 3" vertical pump (which I got a look at but do not own, so I will not post them), which for some reason has the internal ports done completely differently, crossing from the upper left to lower right, and lower left to upper right. Dont know why they are different, but the follow discussion is based on the 3" vertical pump design.


There are two normal style D-valves, but not connected to the normal eccentrics. The one on the left is held by what they termed the 'shuttle'. That, part 16,  is a long cylinder with a narrowed down center to grab the left valve slider. The shuttle rides in a hole that runs the length of the steam chest. Those guide holes act as a cylinder, and have holes at either end that connect down through the valve plate and over to the ports from the right hand d-valve. Those connections are swapped - the left bottom hole from the shuttle connects to the top right port, and the left top hole connects to the bottom right port. The center port in both d valves goes out to exhaust as normal, and the steam chest is fed pressure from the left side. The top and bottom ports on the left hand d valve, the one with the shuttle, are connected to the top and bottom of the cylinder like in a normal d valve.

The trick is that the left hand d valve is not moved by an outside ride from the crankshaft, since there is no crankshaft. Instead, the pressure through the end holes, controlled by the right hand d valve, push the shuttle up and down, moving its valve slider. When the piston comes up, the arm on the piston rod hits the little stop on the right hand valve rod, pushing the right hand d valve up. The opening on the bottom of that d valve connects the top and center ports on the right side - that top port leads to the lower left end of the shuttle guide hole, so that end of the shuttle rod get exposed to outside exhaust. At the same time, the lower edge of the right hand d valve exposes the lower right port to steam pressure. That lower right port connects to the upper left hole, at the top of the shuttle rod. That puts pressure on the shuttle rod, snapping it all the way down. That exposes the top left cylinder port to steam, and the bottom left cylinder port to exhaust, and the cylinder gets pushed downwards.


Eventually in its downwards path, the arm on the piston rod hits the lower stop on the right valve rod, pushing the right d valve downwards. That does the opposite of before, putting steam to the lower left shuttle end and exhaust to the upper left shuttle end, snapping the left (shuttle) slider all the way up, which puts steam to the bottom of the cylinder and exhaust to the top of the cylinder, which starts moving the piston upwards, and everything starts over.

Now, in any d valve there is one small place where the ports are not in a position to allow steam through. Another clever bit of this design is that starting from cold, no-pressure conditions, say the right valve rod is in that state, with the piston somewhere in the middle so not pushing on either stop. Since the left shuttle is free floating, with no pressure anywhere I am guessing that gravity would pull it all the way down, so that it would be in the state of pushing the piston down, and it would self start even then.

I have everything in a Fusion model, but dont know enough about the animation features to do a proper job of animating all that with colors and transparency and whatnot - if anyone else does, I can share the model to them. It is representative of the Southworth model, but dimensions and shapes are not all exactly to plan, so not good enough to build from - for that buy the kit!

Offline Gas_mantle

  • Full Member
  • ****
  • Posts: 1333
  • North Yorks - UK.
    • My Youtube channel
Re: Southworth 6" Boiler Feed Pump
« Reply #13 on: February 09, 2019, 02:21:30 PM »
Thanks Chris, I think I just about understand it  :headscratch:

Would you be prepared to show the drawing you made, that might help too.

Offline 10KPete

  • Full Member
  • ****
  • Posts: 1560
  • Nordland, WA, USA
Re: Southworth 6" Boiler Feed Pump
« Reply #14 on: February 09, 2019, 04:48:21 PM »
Yep, I figured it out last evening also! Good description, Chris.

The quick operation of the shuttle valve puts full pressure on the piston quickly and then sustains that pressure until the piston reaches the end of stroke. Sooo, the pressure on the water is continuous regardless of the pumping rate.

Air pumps do the same but with different valving....

Really cool!

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.