To pump or not to pump that is the question

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To pump or not to pump that is the question

Post by Gra2472 » Tue Apr 13, 2021 1:06 pm

Good morning live steamers. I have a background in steam locomotive operation from the time I was a teen, mostly on narrow gauge shays and such as fireman and engineer for various railroads. But the live steam world is a bit different than the real world, so I figured I would poll you live steamers on a question that I have been considering.

I find myself thinking about disconnecting the axle pump on my mogul. I have installed a pair of injectors, because having just one grates against all of my real world experience. It made me uncomfortable to have just one. One is an EE the other a Superscale economy injector. Both work perfectly and either one can keep up with the locomotive no problem. I also have a hand pump in tender for emergency water. Personally I am comfortable running with just the injectors, but there are of people out there in the live steam world that might have a good reason or two to keep the axle pump. My only argument is that it is convenient. I can set the pump and more or less forget it while I’m running. It’s like having a fireman. But I also look at it as unnecessary with two injectors. I can’t help but think that its just one more mechanism to maintain.

I am looking for arguments either for or against keeping the axle pump hooked up.

How many of you run with or without an axle pump? Why? Club requirements?
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The Mrs. wants her railroad around the house!
G. Augustus
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Re: To pump or not to pump that is the question

Post by FLSTEAM » Tue Apr 13, 2021 1:17 pm

Why do away with a working backup when all you need to do is leave it in bypass?

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Re: To pump or not to pump that is the question

Post by LVRR2095 » Tue Apr 13, 2021 1:23 pm

It is always better to have something and not need it than to not have it and need it!

I can throttle my axle pump so that it puts in just what I am using when running. This still leaves me plenty to do watching where I am going, attending to the fire etc.

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Re: To pump or not to pump that is the question

Post by Soot n' Cinders » Tue Apr 13, 2021 1:30 pm

I’ve seen a number of guys remove axel pumps when they fail, but I don’t think I’ve seen anyone remove a working one. I’d leave it on with the bypass open and when it breaks you can reevaluate if it’s worth fixing then.
Personally I don’t have any pumps on my shay, I’ve got 2 EE injectors and have only needed the second a handful of times. Usually I just alternate which one I use to try and keep the wear level, though I still tend to use the firemans side more.

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Re: To pump or not to pump that is the question

Post by ccvstmr » Tue Apr 13, 2021 1:40 pm


At one time, the club rules and regs for steam locomotives or boiler equipped devices were supposed to have a minimum of (2) ways to get to get water into the boiler. Can't find that language in the hand book now. Nor did the club specify what type or how many of each type were required.

There are several locomotives in the club that run with (2) injectors only. On the Rutland, there are (4) means of getting water to the boiler: 1) tender hand pump, 2) injector, 3) axle pump and 4) steam powered water pump.

Other than initial boiler filling with treated water, the tender hand pump is rarely used. Can also be used for a non-official boiler hydro test.

The axle pump is used MORE for lowering boiler pressure to get the safety valve(s) to close by pumping ambient temperature water into the boiler. When showing/teaching someone how to operate a locomotive, will use the axle pump at that time as well. One less thing for a newbie to deal with (or me worry they're not attending to the boiler water level).

The steam powered water also pumping ambient temperature water as well. While pushing "cool" water into the boiler which isn't the most desirable means of adding feed's just fun to listen to! On occasion after steamed up, there have been days when I just run using the steam powered pump for all feed water. Operation is verified before leaving the steaming bay area.

The injects. This too is tested before leaving the steam bay area. If there's a problem, I can service the inject right there and get it to pick up as needed. Just need to turn on the water supply to keep my hands from burning.

Would say if you have alternate means of delivering water to the boiler...keep 'em. You never know when you MIGHT need it. Better to have such a device on the loco and not use it...than not have that extra device and NEED it!

Hope this helps. Carl B.
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Re: To pump or not to pump that is the question

Post by mogul327 » Tue Apr 13, 2021 1:41 pm

As John B has said, why do away with a working back-up. You never know when your injectors may decide to pack-up on you. Have seen this happen a few times. A piece of junk from some source on the engine gets in the cones and that's the end of that. I have run a few engines without axle pumps and they're fine and work great by themselves. I just think its the ease of running factor that appeals to me where I can set the bypass and control how much water is going to the boiler and how much is being sent back to the tender. A lot of people like axle pumps, many dislike them; it's just your preference. As long as the pump is easy to access and maintain should it be necessary, you should have no issues with needing to remove it.

Just my 2 cents whatever it may be worth.
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Re: To pump or not to pump that is the question

Post by NP317 » Tue Apr 13, 2021 1:56 pm

Argument for keeping your axle pump:
My steam background is also includes decades of full-sized standard gauge steam locomotive operations, restoration, and maintenance.

My Allen Ten Wheeler has
-a stock designed axle pump,
-one SuperScale economy injector,
-one steam pump,
-and one tender hand pump.

In 16 years of operation,
-I've primarily used the axle pump, which supplies ~90% of all the boiler's water requirements. Set and forget.
-occasionally used the injector for makeup when needed, (throttled back on the water delivery!)
-never used the steam pump (but it looks nice...)
-and I use the tender pump at every fire-up to test its operation.
I also have that tender hand pump plumbed through axle pump, so it gets "primed" with every use of that hand pump.

I have never had a failure of the axle pump, and never needed to remove it for maintenance.
Occasionally the injector gets pissy due to a leaking boiler check valve. I installed a second check in the injector output line as a prophylactic solution. Successful.
And I now pay more attention to the boiled check valves servicing.

Keep your working axle pump. Enjoy having two working injectors.
My 2 cents worth.

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Re: To pump or not to pump that is the question

Post by Bill Shields » Tue Apr 13, 2021 6:43 pm

One can never have too many ways to put water into a boiler.
Too many things going on to bother listing them.

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Re: To pump or not to pump that is the question

Post by Gra2472 » Tue Apr 13, 2021 8:42 pm

Great arguments guys!! Thanks a bunch for your insights. My only reason to disconnect the axle pump is simply, it’s one less moving part. I’m in the process of finishing up a two year overhaul, and I’m to the point of plumbing up the axle pump.

7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The Mrs. wants her railroad around the house!
G. Augustus
Monte Rio, Ca.

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Re: To pump or not to pump that is the question

Post by Crosshead4 » Tue Apr 13, 2021 9:49 pm

As others have said full size locomotives all have two devices only. That's what i'm used to and having two injectors only on
my engine feels completely natural. On full size engines I never had both of them fail at the same time. Of course this is a hobby
so theres nothing wrong with having more. Enjoy!

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Re: To pump or not to pump that is the question

Post by Pontiacguy1 » Wed Apr 14, 2021 7:46 am

A little bit of background: Most clubs and organizations required 2 methods for putting water into the boiler, and one of them had to work with the engine standing still, I.E. it couldn't be an axle or crosshead pump. Back in the earlier days of the hobby, the axle pump was seen by most builders and operators as the most reliable method for putting water into the boiler. It was also the easiest to build. Steam driven pumps were difficult and time consuming to build, so a lot of people didn't do that immediately when building a new locomotive. Back then, most of the injectors available were finicky, temperamental, and had a pretty narrow band of pressure in which they would work satisfactory. Ohlenkamp then started making injectors, which worked really good, but the thought process was already imbedded, and most people still used a mechanical pump of some type on their locomotives. From Ohlenkamp to SuperScale, and L.S., and now to EE, there are injectors available that work well, are reliable, and have a wide pressure range. If this was the case 50+ years ago, there would probably be a lot more locomotives that were built without axle pumps. Most of the locomotive designs that are available for commercial purchase today were first designed and built back 40+ years ago, so most have some type of axle pump or crosshead pump in the design.

Like others have said: If it's working, just keep it lubricated, change the O rings out every few years, and leave it in there. It's always good to have more ways to put water into the boiler. If you find that after 2 or 3 years you've never used it, then maybe consider taking it out the next time you have to do any major repairs. I'm working on a locomotive right now that doesn't have an axle pump. The way the frame was built, it would be almost impossible to add one without cutting and modifying big sections of the frame. So... It will have 2 EE injectors. One is a small-scale injector and the other is the standard size injector. The small scale one would run it, but you'd need to leave it on for a lot longer each time. I figured it would be nice to have two different sizes on there, so you could run the smaller one if you were sitting in a yard or something, and use the larger one out on the main. Just my thoughts about it.

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Re: To pump or not to pump that is the question

Post by Marty_Knox » Wed Apr 14, 2021 7:57 am

An axle pump can be a pleasure to have when working properly. I have built 8 Allen locomotives but I have never piped them up the way the drawings show. I make the suction line 3/8" OD and the delivery lines 5/16" OD. I have a tee in the delivery line with one line going to a check valve and a bypass line going to the tender. I put the bypass valve high up on the right front of the tender. This requires a high pressure hose between the locomotive and the tender. But if you have a hole in the tender top behind the discharge of the bypass valve you can see if the pump is working on not. The usual cause of an Allen axle pump not working is the suction ball stuck to the seat. This usually happens if the locomotive has sat for a while.

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