Questions about driving trains.

[TDK]

When coasting a train are you just cutting off the fuel?

Or is it similar to in a car where you have a clutch to disconnect the engine from the wheels.

Thanks

When coasting the engine if it is a diesel reverts to idle, it is the same principle of when in a car putting it into neutral or dipping the clutch but a lot more complicated. All a driver does is shut off the power by putting the power controller into the off position.

 

[PermitToTravel]

Can trains freewheel whilst "in gear", so to speak? Is it more like coasting a bicycle?

 

[Cherry_Picker]

Depends on the type of gearbox. A lot of DMUs will have a fluid coupling instead of a mechanical clutch and therefore the engine is never really connected to the wheels and the train can coast for miles.

If you are unsure what a fluid coupling is then imagine two propellers inside a bath of oil. One is connected to the engine, the other to the wheels and the oil completely encases both. When the engine turns it spins one of the propellers which stirs the oil which causes the other propeller to spin which then turns the wheels. Cut power to the engine and the it just settles down like your analogy of free wheeling on a bicycle. It's slow to accelerate but it can shift a hell of a weight and it will last forever without breaking down.

 

[PermitToTravel]

Very interesting - thank you for that information!

 

[Jamesb1974]

When coasting a train are you just cutting off the fuel?

Or is it similar to in a car where you have a clutch to disconnect the engine from the wheels.

Thanks

Can trains freewheel whilst "in gear", so to speak? Is it more like coasting a bicycle?

With diesel electric locomotives there is no physical connection as such, between the power source and the wheels. Unlike in a car, lorry or even diesel hydraulic locos such as the Western etc, there is no prop shaft or gearbox to link the diesel engine to the wheels.

Diesel electric locomotives have a diesel engine that is connected to a generator/alternator. This produces electricity that in turn, powers motors on the axles of the locomotive via heavy duty cables. Therefore, there is no 'gear' to speak of. There is a forward or reverse direction, but all that does is to select which way the motors turn; forwards or backwards. Thus, when a loco hauled train is coasting, all that is happening is that the motors are freewheeling and no power is being generated by the generator/alternator to power them. The diesel engine is still running, albeit at idle speed. This set up means that diesel electric locos can have diesel engines that run at lower speeds, rather than high revving engines of the kind found in cars, lorries, diesel hydraulic locomotives. For example, the maximum revs on a class 66 is 904 rpm. Compare that to a diesel powered car, which could rev out to around 5000-6000 rpm.

Diesel hydraulic locomotives and DMUs of the first generation variety, had diesel engines connected to the wheels via gear boxes, prop shafts and clutches. The engines had to rev higher to achieve the same effect that a diesel electric loco does at lower engine speeds.

 

[Nic nic]

hi may have already been covered but what is the time limit for driving a freight train, ie how often do you need to take breaks?

 

[A-driver]

hi may have already been covered but what is the time limit for driving a freight train, ie how often do you need to take breaks?

I don't know exact times for freight specifically but if it helps with what you may be getting at, very few long distance freight trains will have a single driver. Like passenger trains practicalities of breaks, getting back to Home Depots within time and road knowledge mean that you may have several drivers to a single freight train.

Generally the limit on passenger TOCs is around 5 hours in the chair before you require some form of break.

 

[bramling]

I don't know exact times for freight specifically but if it helps with what you may be getting at, very few long distance freight trains will have a single driver. Like passenger trains practicalities of breaks, getting back to Home Depots within time and road knowledge mean that you may have several drivers to a single freight train.

Generally the limit on passenger TOCs is around 5 hours in the chair before you require some form of break.

For comparison, on LUL, maximum driving spell (this means time spent in charge of a train, which includes changing ends etc) is 4 hours 15 mins. The maximum time on duty without a break is 5 hours 15 mins, some of which could be spent travelling to another location or sitting spare working to manager's instructions.

 

[richieb1971]

I'm more interested in signals.

If its foggy what is the procedure if you only see the light 3 seconds before your onto it?

I've seen trains move through red lights before.. but usually when this happens there is a light on the ground. Why use the light between the tracks when you have a light overhead?

 

[A-driver]

I'm more interested in signals.



If its foggy what is the procedure if you only see the light 3 seconds before your onto it?



I've seen trains move through red lights before.. but usually when this happens there is a light on the ground. Why use the light between the tracks when you have a light overhead?

Not sure what your last bit means. If you mean a co-acting signal where you have a signal on the floor and one on a gantry its to improve sighting - often a tunnel or bridge can obstruct the view and so an extra one is in place to aid sighting.

Co actors were installed on the down leading to Woolmer green on the ECML as the over head wires cross crossing made a steady yellow/double appear to flash so drivers approached at 70mph right up to a red.

 

[richieb1971]

Its a bit hard to see -

https://www.youtube.com/watch?v=b95WGg-KKvI

43:19 minutes in 56113 passes Eastleigh. It uses the light on the floor to progress. It was the only train during that day that used that light. On all other freights and passengers an over head light was used.

 

[455driver]

Its a bit hard to see -

https://www.youtube.com/watch?v=b95WGg-KKvI

43:19 minutes in 56113 passes Eastleigh. It uses the light on the floor to progress. It was the only train during that day that used that light. On all other freights and passengers an over head light was used.

No it doesn't it has already passed the relevant signal before the end of the platform.
--- old post above --- --- new post below ---

I'm more interested in signals.

If its foggy what is the procedure if you only see the light 3 seconds before your onto it?

I've seen trains move through red lights before.. but usually when this happens there is a light on the ground. Why use the light between the tracks when you have a light overhead?

I take it you know very little about signalling and are assuming an awful lot.

If the driver only sees the signal 3 seconds before he gets there then that's it really, the driver will know what indication they got on the previous signal and will know where the next one is and will drive accordingly, its called route knowledge. I have driven trains at 90mph when I couldn't see the rails in front of me because of the fog, its no big deal.

I assume the light between the tracks was showing 2 white lights at 45 degrees, this is a position light signal and means a different thing to a main aspect.

 

[richieb1971]

Its quite probable I know very little. I thought this thread was to educate people like myself who know very little.

I remember the day well when 56113 came through. A man said to me when the light between the tracks goes yellow get prepared for the 56 to arrive. So I know the light was for the 56, I just don't know why it came on and what relevance to the driver it has.

All I know for certain about signalling is the zoning procedure. Which states that green is line speed.. Double amber is a prelim caution and is usually found just after a green. A single amber means "caution" and that the next light is red. At a single amber the train should have slowed enough to stop at the next light if its red. Red is danger. Under no circumstances are you supposed to pass a danger light unless the signal man instructs you to (dodgy light or something).

You can correct me if I am wrong.

 

[HSTfan!!!]

There's many reasons for you to pass a red signal not just because it's faulty. You also have position lights associated with the main aspect, so you may have a red signal but you can proceed at caution on the position light being cleared.

 

[455driver]

The yellow light you are referring to is for the foot crossing across the tracks, it isn't a signal for the train driver.

I can think of a few locations where if you slow down at the single yellow you wont get to the red because of the gradient.

Its okay for a basic rule of thumb but isn't cast in stone.

 

[richieb1971]

Gradients are problematic for passenger trains? Freight I can understand but not passenger trains.

 

[cool110]

Assuming that you coast from the yellow it's worse for passenger trains as the lower weight means that they won't have enough momentum to get up the hill.

 

[TheKnightWho]

Assuming that you coast from the yellow it's worse for passenger trains as the lower weight means that they won't have enough momentum to get up the hill.

Their power/weight ratio is considerably higher, so this is a non-issue.

 

[najaB]

Their power/weight ratio is considerably higher, so this is a non-issue.

Power/weight ratios are irrelevant if you're coasting.

 

[Juniper Driver]

All I know for certain about signalling is the zoning procedure. Which states that green is line speed.. Double amber is a prelim caution and is usually found just after a green. A single amber means "caution" and that the next light is red. At a single amber the train should have slowed enough to stop at the next light if its red. Red is danger. Under no circumstances are you supposed to pass a danger light unless the signal man instructs you to (dodgy light or something).

You can correct me if I am wrong.

I've never really looked on green as line speed.Clear to go I suppose but other limitations may mean that you don't necessarily have to travel at line speed.
http://en.wikipedia.org/wiki/UK_railway_signalling#Colour_light_signals

This link may prove you right but as I'm a more defensive driver now I don't really look on it like that.(That is actually quite an interesting page)

 

[Minilad]

Their power/weight ratio is considerably higher, so this is a non-issue.

Great. I will coast up the Lickey next time. I'm sure I will make it to the top if it's a non issue

 

[notadriver]

Deleted

 

[Juniper Driver]

Anybody seen one of these.We have one along the routes I drive.Not sure if there are more on the SWT system.

 

[najaB]

Anybody seen one of these.We have one along the routes I drive.Not sure if there are more on the SWT system.

I believe there are some on the WCML - pretty sure I saw one on the up line at Wigan North Western.

Edit: Mmm... I was pretty sure it was a white/green one, but looking at a video on YouTube it may just be a normal LED banner repeater.

 

[t_star2001uk]

They have them on the GWML as well....

 

[Minilad]

More and more are appearing as new signalling works are completed. Three stage repeaters will show On, white and green depending on what the associated signal shows

 

[GB]

Assuming that you coast from the yellow it's worse for passenger trains as the lower weight means that they won't have enough momentum to get up the hill.

Horses for courses. Red light at the bottom of a gradient and you can have 2000 ton pushing against you.

 

[Dieseldriver]

Anybody seen one of these.We have one along the routes I drive.Not sure if there are more on the SWT system.

There's one approaching Keynsham on the down. Technically on your network because some SWT services go to Bristol Temple Meads.

 

[A-driver]

I believe the green banners are the new standard so appear anywhere a new repeater is put in. A few on the ECML-Alexandra palace and harringay and also at sandy although those still only show white for some reason. But when they were installed the other year we were briefed that they would show green once wired up.

 

[Juniper Driver]

There's one approaching Keynsham on the down. Technically on your network because some SWT services go to Bristol Temple Meads.

Don't know it as I only sign as far as Salisbury,but I did suspect there were others about.