axle pump on tender?

[durhambuilder]

I'm just about to start to build a 5" Super Claud (Martin Evans design). The boiler feed is shown on the drawings as two injectors and a tender hand pump. I'm keen to fit an axle pump instead of one of the injectors but there is probably not a suitable place on the main loco, the front main axle is full of eccentrics and inside cranks etc and the rear is directly below the firebox / ashpan so not idea. I was wondering therefore whther it would be ok to fit an axle pump on the tender with a suitable coupling to the loco? My main concern is that the load on the pump will cause the 'undriven' tender axle to lock up, am I worrying un necessarily?
Thanks

[baggo]

It has been done. Nick Feast fitted a tender mounted pump to his recent Q1 design but did comment that you have to reduce the diameter of the ram to avoid locking the wheels when pumping against full boiler pressure. He suggested a ram of only 5 or 6mm for the 3.5" Q1. You should be able to use one a bit bigger for the Super Claud but probably nowhere near as big as a loco mounted one. You could fit a twin ram pump to increase the output.

John

PS I don't know what castings you have already but there are some as part of the workshop clearance that Waggy and I are helping with. There's a cylinder set in CI, main horns, saddle, chimney, dome and inner dome. There may be some of the wheels as well. If you are interested, let one of us know

Just looked at the list again - there's also eccentric straps, big end brasses, motion plate, smokebox door and ring.

[durhambuilder]

John,

Many thanks, I'll pm you about the castings.

Going back to the tender axle pump if I use sufficient one way clack valves can I tee this into the 'handpump' feed and just have a single connection to the loco?

Cheers

[Jim]

Just thinking out loud, but why couldn't you fit the axle pump to the driving wagon/bum truck. There would be plenty of adhesion, well in my case there would , allowing a bigger ram to be fitted.

Jim

[itsbluesteel]

Another small observation whats wrong with just having 2 injectors? plus you have an emergency hand pump !!!

Steve


PS my 5" Hall just runs on 2 injectors, no axle pump or hand pump.

[Andrew C]

No Jim I'm sure that's not the case

There are also crosshead pumps that could be used. Can anyone confirm if Martin Evans terrier design had an axle pump? If so on which axle ? Just thinking it is a tiny and crowded space in there. I'm sure it could be done.

There are those (not me) who say all you need is a couple of good injectors.


Andrew

[taff]

Hello all,
Just to support the injectors comments I have built fifteen 5" gauge loco's to date and have only once fitted a pump which was a crosshead pump on my very first model. This was removed after the very first steaming and I have only ever relied on two injectors per model ever since. Each to his own of course but I am of the opinion that pumps, whether axle driven or otherwise are not worth the trouble of making and fitting or operating.

Taff.

[steam4ian]

G'day

I don't lay any claim to being an expert driver but I have driven 5'G locos with either 2 injectors or an axle pump. In each case it is with regular passenger loads on public open days. Our club track has reasonable grades so the water rises and falls significantly in the glass according to the grade and the steam demand.

The axle pump locos need less tending once the bypass is set up. However the injector fed locos are not much more difficult to manage and you do have more control over the boiler pressure and its more like handling the big ones..

Make sure you have plenty of water and steam space over the firebox. My own loco was very restricted in this department and was quite a challenge. Going down grade you all but lost the water in the glass but then had a full glass on the uphill section, openning the regulator only lifted the water level further.

Recently an experienced driver at our club had to have his boiler retested after losing the water. His problem was not so much a tight steam space but having the bottom of the gauge glass too high so the actual glass was very short. In the heat of the moment a full glass looks the same as an empty glass, particularly if the glass is dirty. It wasn't me, but don't ask me how i know

Regards
Ian

[Nigel Bennett]

Going back to the tender axle pump if I use sufficient one way clack valves can I tee this into the 'handpump' feed and just have a single connection to the loco?

Cheers

That is perfectly possible; I've done it on my Edward Thomas. However, I had to design a cunning non-return valve disguised as an injector so that the hand pump wasn't being affected by the by-pass valve. Pumping away at the handpump like billy-o only to find that I was merely moving the water back into the tank again wasn't a Good Plan.

[ejparrott]

LBSC's Lion has 2 crosshead pumps in a very restricted space, if I need to work on them I turn the engine upsidedown.

All our engines have crosshead or axle pump in addition to injectors and I'd never be without them. My Hunslet suffers from having a tank mounted injector which means it gets hot and wont pick up, the pump can always be relied upon, and I can set the inlet restriction and forget unless the loading chances significantly.

[baggo]

Oct 6, 2011 12:19:20 GMT ejparrott said:

All our engines have crosshead or axle pump in addition to injectors and I'd never be without them. My Hunslet suffers from having a tank mounted injector which means it gets hot and wont pick up, the pump can always be relied upon, and I can set the inlet restriction and forget unless the loading chances significantly.

Have to agree with that totally. I wouldn't be without an axle/crosshead pump if I could fit one in. Just set it and forget it. Someone ran into the back of me a couple of years back cos he was faffing about with an injector instead of looking where he was going

I've found injectors to be pretty useless on a tank engine unless you change the water every lap to keep it cool. It's very difficult to insulate the tanks enough to stop the water getting warm. The best way is to feed the injectors from a separate tank on the driving trolley. The late Jim Ewins was reputed to have made injectors that would pump hot water but I've not managed to find the design yet! No problem with a tender engine but I'd still have an axlepump

Here's a drawing I did for Pete (Greenglade) showing how to use an extra clack to get over the bypass problem. This was for feeding the axle and handpump into the same clack but is similar to what you would do if the handpump and axlepump were both in the tender.

Attachments:

[leighsailor]

Greetings, baggo, I have looked at your sketch of the pipework arrangement, and wonder why more people do not couple the hand pump discharge directly into the suction of the axle pump, which solves the problem, and also allows for the hand pump to be used to clear/prime the axle pump. The axle pump pulls its water through the hand pump, lifting the hand pump balls, and keeping them free.
To use the hand pump, the byepass must be closed.
I have used this system on many locos, and it works well.
However, modern injectors are very reliable, particularly if fitted with a through water valve, and a Ewins type pull on steam valve.
regards
leighsailor

[baggo]

Quite a few of the 2½" brigade use that method as space is tight for all the connections between loco and tender. I've done it on the Kingette that I'm working on. The only possible problem is that it could be argued that because both the pumps are feeding into just one clack, it is only one feed into the boiler so you would need another e.g. an injector.

John

[GeorgeRay]

Martin Evans Terrier design doesn't have an axle pump. It does however have a crosshead driven pump instead. This more than keeps up with the demand on our club track.

[ianholder]

I believe that some of the Aster gauge 1 locos had tender axle pumps. At the other end of the scale, the late Ted Martin installed them on a 71/4 gauge tender. He used two double acting pumps which would would reduce the loading and also gave a continuous feed.

[durhambuilder]

Thanks guys, lots of useful information. The Claud wil be my second loco, the first being a 5"AJAX. That has a pair of 3/8 axle pumps with a similar sized boiler and cylinders. Nothing against injectors (yet!) but I like the simplicity of the axle pump in maintaining a steady waterlevel.

Cheers