How's it all work then?

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How's it all work then?

Post  LilyJack on Thu 09 Apr 2009, 12:29 pm

Hi boys n girls,

Just a question okay and I know some are going to chuckle at this BUT, when you send out kits regards to cylinder etc etc, do you have any paperwork with them to explain their function? As in erm, steam entry and exit points? Just a question from someone thats never steamed an engine let alone build one. I can see you all singing "The wheels on engine go round and round...." But to me it seems quite important knowing exactly whats what and HOW it all works

Cheers, oh and Happy Easter all.. Very Happy

Best Regards

LilyJack

LilyJack

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Re: How's it all work then?

Post  hughb on Thu 09 Apr 2009, 8:13 pm

HI
As for me I have only had a mamod so I am trying to find my old books on this .
I do understamd that the water in the engine is going round all the time .
I am shaw that STW will tell us at some point

hughb

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Re: How's it all work then?

Post  northburrell on Thu 09 Apr 2009, 10:23 pm

Hi Lilyjack.

Ok well here goes this could be long.


Water in the boiler fire in the box (the easy bit Very Happy!) the water boils and makes the steam in the space in the boiler were there is no water and builds up to make pressure.

Traction engines are known as wet steamers. The steam passes throught a hole under the cylinder and into a port and goes round the outsie of the bore of the cylinder. The steam goes into a chest in the top of the cylinder this has the regulator in there and the safty valves on the top. when the regulator it's opened steam passes through the hole under it straight into the valve chest this is why there known as wet steamers.
(steam loco's pass the steam from the regulater out the boiler via a pipe, this pipe then goes back though the boiler in another tube to the firebox turns 180 back up the same tube to the front smokebox, this is were it goes into the valve chest and cylinders. This drys the steam and also heats it up even more for extra power so there called super heaters) as a traction engines steam comes straight off the boiler it's not dried or super heated and is wet)

In the valve chest there are three ports cut into the valve face. one on the left goes to the front of the piston and the one on the right goes to back of the piston. the midldle port is the exhaust port.. There is then the valve that sits on the top of the ports and slides forwards and backwards. When the reverser is moved forward (in the need to move the engine forward) it drops the expansion link (the vertical slide that you can see behind the piston with the two eccentric arms bolted to the top and bottom) the eccentrics on the crank make this link tilt forwards and backwards, when the link is dropped it pushes the valve and slides it over the ports in the valve chest in the direction it's tilted. tilted to the front and with the link dropped down pushes the valve to the front of the cylinder and uncovers the port on the right (or back) of the chest, this takes steam to the back of the piston and moves it forwards and vice versa. It's all timed to were the piston is in the bore and were the eccentrics are positioned on the crank for the valve timing.

when the regulator opens steam comes into the chest and into the open port, this pushes the piston to the other end. as everything is turning round the the eccentrics on the crank tilt the expansion link the other way let say backwards, sliding the valve the other way closing off that port and uncovering the other. the valve has a cut out dished bit in the middle of the valve face, as the steam port that was open is covered up and closed this dished bit of the valve face runs half over the port just closednand half over the middle exhaust port. this takes the steam just used to move the piston, back out the port it just came into the dished bit in the valve face and into the exhaust port, it then goes through the blast pipe and out the chimney. As this is happening more steam is going into the other port and the howl thing goes round in circles..

The blower valve that we just got in kit 20 up next to the chimny is used to pass steam from the boiler up the chmney creating a draft that draws the fire and makes it rour and glow red hot. this is mainly used if the engine is sitting about in steam and not doing much. It can be just opened a small amount just to keep the fire burning nice and the steam at a decent pressure. if you have let your water and pressure go low when driving about then water is more important to get into the boiler than having pressure, when you add the cold water into the boiler the pressure will drop as it takes the water off the boil. turning the blower open will draw the fire and make that cold water turn hot quicker . While this is going on get some coal on the fire... you wil find you can add allot of water fast and keep your pressure up but you should never let your water get low..

The water pump on the crank has a valve that is opened and closed. it's pumping all the time when the crank spins but you will only get it to inject water into the boiler when the bypass valve is shut. this then forces the warter through the clack on the side of the boiler. when it's open it just goes back into the tank. the other means of getting water in is to use the steam injector. this has a valve for the steam and valve for the water. the steam passes through cones in the water valve that speeds up the steam as it passes the water and takes the water with it resulting in fast water delivery to the boiler. this is the best way of getting water in fast if needed. the water lifter works in the same way but it sucks water up. well there ment to i'm not sure they work that wel on models without being primmed first with water.

The water gauge blow down the one i made a new handle for is just used to clear any air bubbles out of the glass so you get a correct reading on your water gauge.

other bits like the brake and steering do what they say on the tin really.

and i think thats about it really. It's fine balance between keeping a nice fire enough water not too much (primming will happen) not too little (ER BOOM well no fusable plug will melt and wet your fire) and keeping enough pressure and using the steam well all at the same time.
You will get the hang of it and be at ease after a few steams

I'v tried to brief I dont know how much you know so i'm sorry if some of it's blatantly obvious hope it helps..

northburrell

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Safety

Post  TB on Fri 10 Apr 2009, 12:34 am

Just to add to the very comprehensive description supplied by Northburrell, I think it is worth mentioning a few points about safety when operating a steam powered machine. When under working pressure, the boiler stores a very large amount of energy which if suddenly released can cause a vaste amount of damage. This occurence happens VERY rarely and is usually due to either to mechanical/material failure or lack of attention by the operator.
The boiler must be inspected and tested at intervals specified for that type of boiler by an approved inspector and a certificate issued. When operating the engine the most important factor is that the water level must not be allowed to get too low, ie down to the level of the firebox top or at the bottom of the water gauge. If it does, the top of the firebox can reach a temperature high enough to weaken the metal/joints, especially in a copper boiler. (not all boilers have a fusible plug that works--personal experience)
With this borne in mind, steam engine building and operating can be a very enjoyable hobby. so lets enjoy it without Health and Safety breathing down our necks.
TB.

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Re: How's it all work then?

Post  LilyJack on Fri 10 Apr 2009, 3:14 am

Very Happy Thanks for your input on this question NorthBurrell and TB, much appreciated, nothing there is too overwhelming to read in digest, it's a simple case of not knowing, therefore we ask do we not Cool .
I know Steve and Dean said that when the engines ready to fire for the first time ( a long way off at the moment unfortunately Crying or Very sad ) that I should bring it down to the works where everything will be gone through step by step so I am very much looking forwards to that day. But to know how it all works and why and where as its being built will give me and any other "newbie builders" a better insight into component functions rather than "ooh thats nice n shiny n turns that bit n that goes in that hole there" kind of attitude.

Thanks again

Best Regards

LilyJack cheers

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Re: How's it all work then?

Post  hughb on Fri 10 Apr 2009, 9:55 am

HI guys
Thankyou for the input .Some I do know but most I do not .It is intresting about the fire bow water levels

hughb

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Re: How's it all work then?

Post  northburrell on Fri 10 Apr 2009, 11:26 am

Hi everyone.

Lileyjack ii'm glad it helps you out mate.. It might be hard to visualize it all if you havent seen the parts but when you get the cylinder and other bits you will see the pieces i'm talking about and know a little more about them..

steam engines are pretty simple really and this type of Stevensons valve gear is easy to look at and work out. When you get up to getting it all linked up and moving round some time spent studying what moves what etc can help you to understand it better...

TB is right, safety is very important.. The most important thing about any steam engine is the water level it must never not be visible in the glass.. Very fast action is needed if you find yourself in this situation.. If you cant get water in fast enough then you must drop the fire out and start again. you must also with a traction engine watch how steep a hill you might be going down. up hill is not so bad as the water covers the firebox but once you have got up there you have to come down, this will make the water rush to the front of the boiler uncovering the firebox causing damage to the boiler and can also make the engine prime (water taken through with the steam into the cylinder. As a driver you get very wet)

All the bits turning round are a big hazzard, fingers should not be put anyway near it unless you want the engine you spent a long time lovingly building to bite! and badly! Allways make sure if the engine is sitting around in steam that it's in mid gear and out of gear with the selector locked in with the pin. the valves on steam engines work but they do leak with 80 to 90 psi surrounding them, the worst thing you want is to be chatting to someone and your engine takes off on it's own.. I'v had a Loco run away from me and it's not fun trying to catch it.

lubrication is also very important and oil levels, Steam oil and bearing temperatures should be checked once or twice if running for long periods of time. more so for a newly built engine.. and the first steaming this should be looked at all the time. You dont want a hot binding bearing or something not getting oil.

I would say to anyone that has never steamed and engine before that they should go to STW for them to get it setup and steam tested. Or find your local model engineering sociaty pop down when there running and make some new friends, there's allways someone that will give you your first drive of steam engine.. And you might want to try a Loco out.

anyway enough typing i'm going to do some well put off linning.. Very Happy

ps Sorry for any bad spelling etc. I was blessed with dyslexia.. Laughing but i can spell that!!! I think..

cheers.

Jo

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