Here is a list of all the postings Gas_mantle. has made in our forums. Click on a thread name to jump to the thread.
|Thread: Hot rail tracks|
The track circuits are actually nothing more than a simple low voltage circuit that trips a relay once short circuited by the wheels of a train, this relay can then be used to energise other circuits that are vital for the working of the signalling system. In old manual signalboxes before the introduction of track circuits the signalmen could look out of the window and see the postion of trains under their control but in modern installations the signalman usually can't see the trains under his control so the track circuits display vital information of the precise location of trains relative to the points and signals.
The new signalbox at York is still only partly operational but is planned to control the entire East Coast Main line from Kings Cross to the Scottish border. Didcot signalbox just west of Reading already controls London Paddington to Bristol. The intention is to control the entire UK network from 17 signalboxes over the next decade or 2.
When the old joke about leaves on the line crops up every autumn it does make the UK rail system sound a laughing stock but the general public don't realise it is a serious condition that affects the integrity of the signalling system and potentially can be dangerous. Modern rolling stock tends to be fitted with disc brakes so there are no brake shoes cleaning the wheel running surface at every brake application, over time a mulch of squashed leaves builds up on the wheels surface this can then start to insulate wheels so that track circuits no longer operate reliably. It's be no means rare for trains to 'disappear' off the signalmans display which of course can be very serious. Of course a build up of mulch on the wheels does affect braking capability and that in itself is a safety issue but in a lot of cases leaf fall delays are when more stringent signalling rules are invoked because of track circuit unreliability.
Incidentally, on track circuited lines (probably 90% of the current network) if a rail breaks provided the break is a clean fully open break the track circuitry is destroyed and the protect signal should revert to danger automatically.
To return back to the track, in the 60s / 70s it was decided to install steel sleepers on some none high speed lines, the idea was the were cheap and supposedly maintenance free, however in reality they were more of a nuisance than they were worth. As you can imagine steel sleepers are far more inclined to absorb heat making them a pain in the summer when rail expansion is a problem
Edited By Gas_mantle. on 30/06/2018 11:40:08
Most rails are hot rolled steel and for CWR they are typically in 600ft lengths.
Manganese is used mainly on pointwork, diamond crossings etc where there will be heavy usage / wear.
It's not often realised but in modern installations the rails are fed with a very low voltage but are electrically insulated from each other, the wheels of passing trains short circuit the rail to show the position of trains which can be controlled by a signalman 50 miles away.
Continuous welded rail is mounted directly onto the sleeper without the old fashioned 'chair' fitting common in older installations. A small rubber mat under the rail bottom adds a cushioning effect as well as provide electrical insulation to the rails if the concrete sleeper starts to crack exposing strengthening wires.
Once the rail is clipped down it should be unable to move.
Dave, the rail is actually stretched despite it sounding far fetched.
In a length of CWR (usually 600ft) stretching by a few inches doesn't take as much force as you might expect and is easily acheivable with pulling kit.
It's usual to retress after rails have been in use for a number of years, this is because the downward forces (and heavy braking in some areas) cause the rails to lengthen (rail creep) and therefore reduce the inbuilt stress. Restressing by removing a small amount of rail then pulling the gap to reweld is primarily about restoring the stress and not necessarily straighten out any slack.
In modern long welded rail sections the rail is cut and welded into place under tension to reduce the likelihood of distortion under expansion. Basically once in situ the new rail is cut slightly too short using laid down formulae to determine how wide the gap should be depending on the ambient temperature at the time of installation. Once cut the resulting gap is often only an inch or 2 but the new rail then needs to be stretched using hydraulic rams (referred to as pulling kit). When the rail is stretched an the resulting gap closed up it can be welded into place, the pulling kit holds the rail under tension until the weld is completed. After welding has been carried out the pulling kit is removed and the excess weld is ground away to leave a smooth continuous running surface.
Effectively it means all continuous weld rail (CWR) is deliberately slightly too short and under constant tension. After years of use the pounding of the wheel on the rail tends squash the rail and make it longer when this happens the risk of heat distortion becomes a risk so it is usual to 'restress' the rails by cutting out a small piece then closing up the gap to reweld it.
Owing to the way rails are installed under tension it is rare for new track to be laid in the extremes of temperature / weather. Ocassionaly after derailment damage it is necessary to intall new track at short notice but ordinarily it is planned to take place when it is expected too be neither to hot or too cold for stressing
This photo shows the pulling kit stretching new rails prior to them being welded under tension.
Edited By Gas_mantle. on 28/06/2018 10:53:39
Edited By Gas_mantle. on 28/06/2018 10:58:19
|Thread: Milling for beginners|
On the subject of DRO's is it much of a job to fit them to a mill? I know the makers usually say its so easy a 5yo can do it but we've all heard that kinda thing before.
I have a Chinesium mill of a similar size and spec of the Sieg 2.7 and have considered a DRO, I don't mind a bit of cutting and drilling but I don't really want to start milling out large slots or dismantling a lot of the machine etc.
|Thread: Stuart Engine as motive power|
Not sure if this is of interest to you but it shows a steam loco powered by a Stuart D10 :-
|Thread: College Engineering Supply Castings Alternatives?|
I've bought wheel castings from the ebay guy so I can say he is a genuine seller and the items I've bought from him have all been great.
As for other castings, I wouldn't necessarily be interested in angle plates or screw jacks etc but if people were clubbing together to try and buy something that is ordinarily is difficult to buy then I may be interested.
I wish he'd make more styles of flywheel
|Thread: Milling for beginners|
How do I view the 2 dedicated threads ? I may have a few questions but the link you gave seems to just take me back to the homepage.
|Thread: Bradford Keighley|
I live between Skipton and Keighley and have a Chester Champion 20v mill I'm happy to let you use if it is big enough.
I've priv messaged my details
|Thread: Vertical Boiler Fittings|
Looking good Gary, I'll be interested to see the finished item
You have spurred me on to have a go at something similar
Gary check your inbox - I sent a private message.
To give you an idea, this boiler is 3" dia with 9 fire tubes so it's probably not much bigger than yours but it comfortably runs my 1" bore engine.
At tickover speed it will probably run the engine for about 10mins with the gas turned off once the pressure is up
Thanks Gary, I have a piece of 3" dia copper tube that I plan to make a fairly simple boiler from but possibly a horizontal.
You should find yours will easily power a small wobbler for a quite a while between refills. I recently built a small entablature engine of about 1" bore x 1" stroke it is double acting but my existing 3" dia vertical boiler will run it at fairly high speed for 20mins and probably an hour just ticking over on a low gas.
I wasn't sure if you have added a clack valve to fill it in use but if not I'd advise it - mine is connected to a 3/8ths ram hand pump and that is fine for this size
Looks good Gary, I'll be interested to see how it performs
Where did you get the plans from ? I'd quite like to have a go making something similar.
|Thread: signal box bell codes|
When I first started working on the railway I bought a copy of this book, it's an excellent read for anyone interested in signalling :-
I'm an ex railway signalman of 30yrs.
By understanding what train was being offered the advance signalman is able to decide to accept or refuse the train dependent on the situation within his own area of control. He may for instance operate a junction, sidings, good loops etc and before accepting a train he needs to know which way it is going at a junction and whether it can refuged in a loop etc
In a simple signalbox with no junction etc the signalman is pretty much compelled to accept the train in the order they are offered but in the case of complex junctions he may want to accept trains in a specific order to avoid delays, congestion etc
|Thread: Couplings - How did they make them?|
The load on a hook lifting is considerably more than it is when hauling.
On level ground an averagely built adult male can push a 12ton railway wagon from a standing start and once going can get a decent speed with little effort, I don't know of anyone who can lift that vertically.
Take a spring balance and take a reading pulling something on the level, keep increasing the gradient and the load increases until you reach the maximum when at a vertical lift
Edited By Gas_mantle. on 13/06/2018 00:51:45
I can't answer your question as such but I do know that it's now usual for the drawbar to have a slot cut out of the top and corresponding flats on part of the shackle to enable it to be removed.
Its just about visible here :-
Edited By Gas_mantle. on 12/06/2018 20:49:30
|Thread: Warco WM250 Lathe and Warco WM18 Milling machine (Advice please)|
In the 250 class of machine I bought a Chester DB10v about a year ago and find it's a great machine for the kind of hobby work I do.
It has powered cross feed, a quick change gearbox and a 'T' slotted cross slide that some machines in this size don't always have.
Before I bought it I deliberated for hours trying to decide which machine to go for, I guess a lot of these Chinesium lathes are essentially the same machine but they do have subtle differences in features (and price). It seemed to me there were plenty of user reviews of the mini lathe but little in the 250 class of machine so I have been considering writing a detailed review of mine after 1 year of use.
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