Line Speeds

[StevieG]

Ay up!

I've seen Evening Star plus 5 stopped on the Worth Valley on a rising gradient using just the graduable steam brake valve.

On the MOORGATE to WELWYN GARDEN CITY or HERTFORD NORTH workings in the early 1970s.

Climbing up from KINGS CROSS L.T. JUNCTION up the 'stiff rising' gradient of the 'Hotel curve' on a Brush type-2 with a rake of 6 or 7 Inner suburban non-corridor stock (block enders to some?) the driver would have the locos controller 'wide open' until just before the south end of no.16 platform and daylight then just 'shut off' power and let her roll through the platform to a stand at the north end, as she stopped apply the engine brake

manna will probably remember that trick

I guess it was pretty much the same in steam days

Didn't some trains purposely come to a stop with the loco just past the alreday-cleared platform starter (the twin-headed 3-aspect KC221)? - That would have allowed a slightly better chance of no slipping back when starting (and if there was, you would've been that little bit further away from the 'jack-catch' just by the tunnel mouth).
Actually, makes me think, anyone get yellows* rather than greens before emerging from Hotel Curve tunnel into the platform (indicating that KC221 was still red)?
* - (First, No.222 distant [the only yellow lever in the box], then 221R just inside the tunnel's exit mouth.)
If not, I wonder if there was a signal box instruction not to accept a train on the Down Met. from KX 'C' (LT) box unless 221 could be cleared immediately (that section was still worked by Absolute Block until the old box was de-commissioned in '71 and all signalling control moved over to the switch panel in the present box building, temporarily [about 5.5 years! ] until the remodelling/resignalling reached 'the Cross').

[Mickey]

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[52D]

Just like a hill start in a car, I learned to drive in an Austin 1100 and they had the added advantage of a bonnet rise when you were coming off the clutch.

[JeffB]

It was common practice when starting out of the 'hole' with any of the diesels, 31s, D5300, D6100s, to open the controller before letting the brake off. If you did,nt you would,nt get anywhere.

[manna]

G'Day Gents

Yep. Micky I remember that now something that I had kind have forgotten ! you very rarely over ran that platform, but as you say open the loco a notch or two before releasing the brake, but if you had a wet greasy rail, and could'nt get away first time, you could have the signal put back on you, had that happen to us, to. Because you always pulled away slowly (like a N2) you used to get people running to catch there train, and they would catch it. !!!

manna

[Mickey]

Deleted

[CVR1865]

Guys,
This is great info. Thanks for the tip about the sectional appendix and line speeds. I will have a look at my 1951 rule book.

I have certainly learnt something about cut-off too, I had always thought it was to maintain a constant rate of acceleration not to increase it. From that might one summise that pulling away on full cut off was to ensure that the loco came off slowly and evenly taking up the load, as apposed to a small cut off that would cause a jirking take up, slipping of wheels and spilling of passengers?

Thanks for all the comms this is top stuff.
Simon

[Blink Bonny]

Ay up, CVR.

A steam loco gets its energy from two sources.

First off is boiler pressure. This is what's needed on starting because it is a constant pressure and is determined by the loco's boiler pressure at the time (obviously) and the design of the steam passages.

However, as the loco accelerates, then using solely boiler pressure steam is wasteful, mostly because we would be ignoring a second source of energy. Expansive pressure. As the loco accelerates, then the piston obviously travels faster so expansive pressure can be used. 20% cut off basically means boiler bressure (to be more accurate steam chest pressure) for 20% of the stroke then expansive pressure for most of the rest. Only most? Well, a small amount of "live" steam is admitted at the end of the stroke to "cushion" the piston and reduce stresses when the direction of motion is reversed.

Juggling the cut off juggles the two sources of energy in the cylinder. For more power, more live steam is required. Theoretically it is possible to drive the loco in full gear with regulator wide open, a process known as "wiredrawing" or, in simple terms "thrashing the nadgers off" but the fireman may well have something to say about this! Certainly at high speed, such a driving method would cause the engine to boil more water than the injectors could deliver.

Incidentally, no modern locomotive has a 100% cut off position. All use expansive power to some degree even when starting.

[manna]

G'Day Gents

I always looked forward to the cooler weather, so I could play about with the steam heat boiler, and and a very good memory was coming out of the tunnel on platform 16, and seeing it seething with passengers wanting to go home, stopping at the end of the platform, and looking out the door window (on the drivers side) and watching everyone all lining up to get into there chosen compartment, the dim gas lights giving off there yellow light, with steam rising from the ends and middle of our coaches, plus a small amount from the front of our own loco, doors banging, whistles peeping, and a green light cutting through the steam, I would say 'Right away' and get a 'OK' in reply, but I wouldn't leave the window until we were passing the fueling shed, then I would close the window and go to my seat, just before we entered 'Gasworks tunnel' Thinking to myself, 'it don't get better than this'

manna

[hq1hitchin]

G'Day Gents

I always looked forward to the cooler weather, so I could play about with the steam heat boiler, and and a very good memory was coming out of the tunnel on platform 16, and seeing it seething with passengers wanting to go home, stopping at the end of the platform, and looking out the door window (on the drivers side) and watching everyone all lining up to get into there chosen compartment, the dim gas lights giving off there yellow light, with steam rising from the ends and middle of our coaches, plus a small amount from the front of our own loco, doors banging, whistles peeping, and a green light cutting through the steam, I would say 'Right away' and get a 'OK' in reply, but I wouldn't leave the window until we were passing the fueling shed, then I would close the window and go to my seat, just before we entered 'Gasworks tunnel' Thinking to myself, 'it don't get better than this'

manna

Wonderful description, mate - you've just conjured up a winters evening during the peak on the GN suburban. We'll never see the like again, a steam railway but run with diesel traction.

[StevieG]

G'Day Gents

I always looked forward to the cooler weather, so I could play about with the steam heat boiler, and and a very good memory was coming out of the tunnel on platform 16, and seeing it seething with passengers wanting to go home, stopping at the end of the platform, and looking out the door window (on the drivers side) and watching everyone all lining up to get into there chosen compartment, the dim gas lights giving off there yellow light, with steam rising from the ends and middle of our coaches, plus a small amount from the front of our own loco, doors banging, whistles peeping, and a green light cutting through the steam, I would say 'Right away' and get a 'OK' in reply, but I wouldn't leave the window until we were passing the fueling shed, then I would close the window and go to my seat, just before we entered 'Gasworks tunnel' Thinking to myself, 'it don't get better than this'

manna

Wonderful description, mate - you've just conjured up a winters evening during the peak on the GN suburban. We'll never see the like again, a steam railway but run with diesel traction.

Absolutely!!
Couldn't have matched it for mental picture-building!

I can only think about adding thoughts about the forward view of the driver as you made a re-start.
A large red beside green right in front of (or by? or just behind?) the cab; 'Passenger Loco's yard lighting poles casting a dim glow over its yard and the motley temporary guests; a candle-like glow of the lights in 'the Loco's one-road 'elephant house' maintenance shed; and straight ahead, a further green signal light high up with a large, dull-white letter (probably 'S') illuminated above it; around 11 red-'armed' white banner signals, plus a forest of up to about 20 other main and small red signal lights, with perhaps a platform number or two lit up above, unless two or three of the reds were instead green, accompanied by the odd 'M2' and/or 'M1' indication : And all visible in the forward vista of no more than about 300 yards.

[Mickey]

Deleted

[strang steel]

Marvellous stuff. I have just been transported back some 45 years.

[manna]

G'Day Gents

Thanks Gents, such a common sight in the early 70's, to us, but then we also had the other side of the coin.....pushing a blast of hot smelly smokey air in front of us as we exited Hotel tunnel, looking at the sweating commuters waiting on the dusty wooden platform, at last we could open our windows and get rid of the fumes that had seeped into the cab, from the hellhole that we had just come through, coming to a jerkless stop, just off the end of the platform, I had to open the door of the cab to allow me to lean out a bit further, to see round the curve of the dingy platform to see the porter who would relay the guards signal, the windows of the coaches were being opened with a bang, as our passengers tried to cool the compartments down.

'Right away mate' you could hear the controller being opened, whistles could be heard being blown on other platforms at the 'Cross' a hiss as the brakes were released, we moved! the engine got louder, building up power, clattering over the points, cool diesel smelling air drifted through the cab, but my shirt was still stuck to me, walking back to my seat I saw the Brush 4 come along side as we entered Gasworks tunnel, racing the Cambridge Buffet, through the darkness of the tunnel, two 12 cylinder engines bellowing against the brickwork, getting warmer again, I though to myself, my driver would never have heard me with the windows open, Ahhh, daylight, Belle Isle.

Stevie G, Didn't always get to see the view, you described, unless the driver had let me have a go, but KX was a busy place in the evening rush, as you were leaving, there would often be a train pulling out of York Road, going down the 'Drain'

manna

PS. Depresses you a bit to remember, what a railway we had then, to what you have now

[Blink Bonny]

Cor!

You lads really have the knack! I was there, simply by reading.

There's a good book in these memories, y'know.