Kozo A3 3/4 scale up and running sort of

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

User avatar
kenrinc
Posts: 708
Joined: Tue Jul 27, 2010 1:11 pm
Location: SF Bay Area

Re: Kozo A3 3/4 scale up and running sort of

Post by kenrinc »

I've built a 1.5" scale Kozo A3 and it runs like a dream and always has. I've got my hand pump plumbed into my axle pump. Regardless of how you currently have it you will have to prime it before you leave the bay. If you don't prime the pump it will never work. Actually that's not entirely true but it may take an entire days run before it primes on it's own :mrgreen: :)

Fill the boiler and the water gauge should show correct level. Once this is verified, check the hand pump. Unscrew the vent plug at the boiler check. Pump the hand pump until a steady stream of water comes out the vent. Put the vent plug back in. Begin pumping and you should be able to verify that water is now going into the boiler. I do this before every run. It's saved me many times.

I'm in the process of adding a vent valve at the exit of the axle pump so it makes it a bit easier to prime. If you built it per Kozo you should already have a vent valve in the original plumbing. I used commercial fittings on mine so I don't have the vent but what I do instead is to unscrew the top of my check valve, pull the shuttle and prime as usual. I built the axle pump 3 times as well. My problem was that my silver solder skills sucked. Since the axle pump is so much more massive in 1.5" scale, I had a hard time getting that mass heated hot enough to silver solder it. Keep in mind that there is a bit of precision needed for the fitment of the o-rings. The bronze bushings slightly press on the o-ring and that's what creates the squeeze that prevents leaks. It's a simple design that works very well once you get it right.

Ken-
User avatar
Bill Shields
Posts: 10460
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Kozo A3 3/4 scale up and running sort of

Post by Bill Shields »

The design of the tender pump is not a concern...single or double...it matters not.

I have known people to feed the axle pump straight through the hand pump.. with the axle pump sucking through the hand pump.

Know sounds strange but it works...and makes things very simple with respect to piping and priming.
Too many things going on to bother listing them.
sky
Posts: 37
Joined: Thu Mar 22, 2018 2:17 pm

Re: Kozo A3 3/4 scale up and running sort of

Post by sky »

Thank you all for the valuable information. I will re-pipe and give it a try.
Might be a while until I get to it, but will let you know what happens.
sky
User avatar
NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: Kozo A3 3/4 scale up and running sort of

Post by NP317 »

I have no need of vent openings at the boiler water input valve.
I plumbed the tender hand pump through the axle pump, then to a bypass valve, and also into the boiler check.
After closing the bypass valve: if I can see water being hand pumped in to the boiler during fire-up (visible in the water glass),
then I know the tender hand pump works, and the axle pump has water in it.
No failures in 16 years of operation.
RussN
User avatar
Bill Shields
Posts: 10460
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Kozo A3 3/4 scale up and running sort of

Post by Bill Shields »

Ever seen an axle pump throttled on the input to control flow instead of using a bypass?

Just cut the seat so that the jnput throttle valve cannot be totally shut dry.

Really simplifies piping since you now do not have need for a return line...just one water line from tender to loco
Too many things going on to bother listing them.
sky
Posts: 37
Joined: Thu Mar 22, 2018 2:17 pm

Re: Kozo A3 3/4 scale up and running sort of

Post by sky »

Hi all,
back again. I have the hand pump in the tender piped to the left side the Engine so it feeds the axel pump. Now having trouble with that little bit of rubber hose between the tender and the engine. No clamp I devise has managed to keep it from leaking. Anybody have any solutions?
User avatar
LVRR2095
Posts: 1688
Joined: Sun Mar 04, 2007 6:50 pm
Location: Maine, USA

Re: Kozo A3 3/4 scale up and running sort of

Post by LVRR2095 »

sky wrote: Wed Nov 17, 2021 11:32 am Hi all,
back again. I have the hand pump in the tender piped to the left side the Engine so it feeds the axel pump. Now having trouble with that little bit of rubber hose between the tender and the engine. No clamp I devise has managed to keep it from leaking. Anybody have any solutions?
I use Poly-Flo tubing with Imperial Eastman nylon and brass fittings. The nuts are brass and the ferrules are nylon. Leak free and the tubing is flexible.

Keith
sky
Posts: 37
Joined: Thu Mar 22, 2018 2:17 pm

Re: Kozo A3 3/4 scale up and running sort of

Post by sky »

Hi Keith,
So, I would have to remake the ends water lines. Kozo has it ending in a pipe and you just put a clamp around the tube.
sky
User avatar
LVRR2095
Posts: 1688
Joined: Sun Mar 04, 2007 6:50 pm
Location: Maine, USA

Re: Kozo A3 3/4 scale up and running sort of

Post by LVRR2095 »

sky wrote: Wed Nov 17, 2021 1:03 pm Hi Keith,
So, I would have to remake the ends water lines. Kozo has it ending in a pipe and you just put a clamp around the tube.
sky
You would just solder the Imperial Eastman male thread fitting to the end of the pipe.
No need to change anything.
Keith
sky
Posts: 37
Joined: Thu Mar 22, 2018 2:17 pm

Re: Kozo A3 3/4 scale up and running sort of

Post by sky »

Nifty idea. Thank you very much!
sky
User avatar
LVRR2095
Posts: 1688
Joined: Sun Mar 04, 2007 6:50 pm
Location: Maine, USA

Re: Kozo A3 3/4 scale up and running sort of

Post by LVRR2095 »

Poly-Flo fittting between engine and tender.
Looks like it is time to clean the locomotive!
84D3C7D2-EC6E-4F29-B443-005860236ED8.jpeg
sky
Posts: 37
Joined: Thu Mar 22, 2018 2:17 pm

Re: Kozo A3 3/4 scale up and running sort of

Post by sky »

Thanks for the picture. As they say, it is worth a thousand words.
Post Reply