simplex

[nobby]

Hello all ;)just found the site and just joined up, been tinkering around with metal for a while usually re-building ex MOD vehicles, but latley moved indoors to a nice warm workshop and trying my hand at building a 5" simplex. I must admit i am not doing so bad been a bit of a perfectionist BUT not knowing that much about steam engine workings and very little information on the Martin Evans plans i have come to a stumbling block and that is were do the steam pipes go to from the cab , how do i get the water from the pump to the boiler and whats a "snifting valve" can anyone give advice or i diagram on the direction of these pipes from the cab they just seem to disapear through the floor. ;D
with thanks
Rob

[SteveW]

Nobby,

I'm not familiar with the Simplex so can't help you there but being in the middle of a Sweet Pea strip-down know what a 'snifting valve' is. If you think about it, the loco gets blown along by pressure from the boiler. If you close the regulator completely, just like in a car, the over run will start drawing a vaccum in the manifold.

As I understand it the 'snifter valve' feeds this vaccum with fresh air thus avoiding any tendency to a braking effect like in a car. It's a simple valve that sits after the throttle and before the valve chest that is held shut when the throttle provides presssure and opens when it doesn't. On our Sweet Pea it sits out through the bottom of the smoke box floor. The other end connects to the valve chest feed manifold.

[baggo]

Hi Nobby,

Like Steve I'm not too familiar with the Simplex design but I do have most of the ME articles describing the construction. They do seem a bit vague in certain areas, especially with regard to the pipework.

So far as I can tell there will be a pipe from the valve on the lefthand end of the steam manifold to feed steam to an injector mounted under the cab floor, a pipe from the whistle valve to the whistle mounted somewhere under the cab floor and a drain pipe from the water gauge blowdown valve. The feeds from the axle driven pump and the emergency hand pump feed into two check valves screwed into the two lower bushes on the boiler backhead. I am sure there are some Simplex builders/owners out there who will probably know better.

As Steve says, the snifting valve is a simple one way valve connected to the steam pipe between the regulator and the cylinders, usually before the superheater, which allows air to be drawn into the cylinders when the regulator is closed, thus preventing a vacuum being formed by the pumping action of the cylinders.

John

[spurley]

Snifting valves have two basic functions; 1. To prevent a vacuum being formed in the cylinders when running with the regulator closed. Particularly suited to piston valve engines as slide valves tend to drop away from the valve faces or just don't seal as well in this 'mode'. This helps both with free running and prevents ash and other 'nasties' being drawn into the nicely oiled cylinders. 2. On a superheated engine the shifter allows a flow of air through the superheater elements when there is no steam applied. This is said to prolong the life of the elements as they should not be burnt by the hot gasses in the superheater flues.

Having said all that, REL Maunsell, CME of the Southern Railway, fittted these valves to all of his designs but along came OVS Bullieid and removed them during his 'improvement regime! The engines seem to work both with and without! All BR standard designs had them fitted so Mr Riddles was a believer.

Anyway that's what a snifting valve does

Cheers

Brian

[spurley]

Hi Nobby

Have a look at this site for more 'gen' on the Simplex

freespace.virgin.net/simplex.steam/index.htm

There is a 'links' tab which also might guide you to a fellow builder?

Cheers

Brian

[greasemonkey]

Hi Nobby
Im building a Simplex. The Snifting valves function has been described above and on a simplex is placed on the lower left hand side of the smokebox. It is connected by a 1/8" pipe to the superheater header. This is a fiddly job and best preformed by somone with smalll hands and fingers!!!!
The run of the water pipes is up to you! The outlet of the water pump is fed to one of the boiler clack valves but needs a bypass arranagement to allow water to ciculate around the system, otherwise you will overfill the boiler. Input to the axel pump is taken via the hand pump in the right hand tank. This method works well and enables you to check that you dont have a sticking ball in one of the pumps, just remember to close the bypass if you need to use the hand pump.
The blower is shown on the plans and runs down the hollow stay in the boiler. Finally the injector output feeds into the second clack valve, steam pipes being routed by any convienient method, with the steam feed comming of the manifold.
cheers

Andy

[nobby]

thanks for that all a great help BUT!!
The outlet of the water pump is fed to one of the boiler clack
the injector output feeds into the second clack valve,
So do i have two feeds in to the boiler ? and if so why the injector this i can not find on my plans.

thanks
nobby

[Tel]

Yes you should have two feedwater clack valves - one on either side of the boiler barrel, one is for the axle pump & one for the hand pump. If you want to add an injector you will need to fit a third clack somewhere, or make a dual feed one for one side

[nobby]

this is fantastic , the workings of a steam engine are are just mind blowing, i have a good knowlege of engineering but this is all new to me, so a few last questions before i push on:
blower valve i know what it is but what will i connect it to in the smoke box
and if i have a axle pump and manual pump why might i need an injector (how will this work)
and where do i put a by-pass valve in the system
well that should do it, gone have the days of thinking a steam engine was a kettle on a burner
nobby

[greasemonkey]

No ,steam engines are certainly not just kettles on a burner just as there is a little more to putting the coal on the fire than opening the door. The blower connects via the hollow stay in the boiler to the blast nozzle! An injector is great as the axle pump only puts water in whilst you are moving unless you want to sit and waggle the hand pump constantly!!!Hand pumps are normally only used in emergencies. The latest boiler regs require 2 independent methods of putting water into the boiler. The simplex boiler as designed doesn't have bushes on the barrel for clack valves they sit on the backhead down by the firehole door. The quickest and easiest way to learn what all these parts do is to ask at your local club, which part of the world are you in?

Andy

[Steve M. W]

Hi Rob

this is an ace site for getting info as you have seen, but why dont you join your local club that way you may get to see a Simplex in steam and talk to builders and drivers who will show you each part working and why its needed, they may even teach you how to drive.

Steve

[Tel]

greasemonkey said:

No ,steam engines are certainly not just kettles on a burner just as there is a little more to putting the coal on the fire than opening the door. The blower connects via the hollow stay in the boiler to the blast nozzle! An injector is great as the axle pump only puts water in whilst you are moving unless you want to sit and waggle the hand pump constantly!!!Hand pumps are normally only used in emergencies. The latest boiler regs require 2 independent methods of putting water into the boiler. The simplex boiler as designed doesn't have bushes on the barrel for clack valves they sit on the backhead down by the firehole door. The quickest and easiest way to learn what all these parts do is to ask at your local club, which part of the world are you in?

Andy

You sure about that Andy? Mine are in the sides of the barrel, but maybe I changed 'em

[greasemonkey]

HI Tel
Yep, my plans only show them in the backhead although a lot of people put them in the barrel which is a actually a better place for them. Infact if you build the boiler to the plans the clacks prevent the firehole door opening properly. Most pro. built boilers are adjusted to prevent this.

Andy

[Tel]

That could be wot I did then. I know I changed a few things along the way - the position of the axle pump bein' one.

[greasemonkey]

Hi Tel
I changed a few things to. I have a top feed at the front, because of my longer side tanks, I only have one bush for an injector on the backhead, no hollow stay for the blower (the valve gets to hot!) and I ditched the girder stays for traditional rod stays!

Andy

[nobby]

The quickest and easiest way to learn what all these parts do is to ask at your local club, which part of the world are you in?
im in the north east (Sunderland) what clube are near here

[greasemonkey]

try the city of Sunderland model engineering society who used to meet at Roker Park. A search on Google will get you some contact numbers

Andy

[ericcee]

Just browsing here before I turn in! I've just spent an enjoyable afternoon running my Maxitrak Jack around the City of Sunderland Model Engineering Society's track in Roker Park - after spending the morning in a Society Committee meeting! We are very much alive and kicking and celebrate our 75th Anniversary this year.
We run there every Sunday through the summer, and often on Saturdays as well. New members are always welcome and Nobby would find a wealth of help and advice - just ask!

Eric C.

[alanstepney]

City of Sunderland MES, contact- Albert Stephenson: 01429 299649
There website appears to be down.

Info from www.modeleng.org/ukclubs.htm

[ericcee]

Sorry - I should have provided that contact information. The website is, in fact, defunct, but a new one is under development.