Steam Cutoff in Driver
- Thread starter spiffy101
- Start date
The same thing it's for in real life.
Steam has considerable power that can be released during expansion, so once the train is moving very little steam is required to keep it going. So a steam engine has a cut-off to reduce the amount of steam admitted to the cylinder while running. This reduces the amount of water and fuel that are used, and allows longer travel before more is needed.
Claude
Steam has considerable power that can be released during expansion, so once the train is moving very little steam is required to keep it going. So a steam engine has a cut-off to reduce the amount of steam admitted to the cylinder while running. This reduces the amount of water and fuel that are used, and allows longer travel before more is needed.
ClaudeHow is the speed affected if it is all the way forward or at 30%. Horsepower?
The regulator controls the flow rate of steam to the cylinders while the valve is open and the cutoff controls what percentage of the piston movement that the cylinder will receive steam during the power stroke. Running with the regulator at 100% allows maximum flow rate to the cylinder while the valve is open which allows the steam to develop maximum expansive power after the valve closes. Speed can then be regulated with the cutoff since it can be adjusted from 75% to 0% in the forward direction or -75% to 0% in the reverse direction. Running with the regulator at 100% and adjusting speed with the cutoff provides maximum efficiency and uses minimum steam.
Bob
Bob
Well said. That's the essential point.
Hi spiffy --
This might be of interest:
http://forums.auran.com/trainz/showthread.php?t=9845&highlight=passed+as+driver
Phil
This might be of interest:
http://forums.auran.com/trainz/showthread.php?t=9845&highlight=passed+as+driver
Phil
Harry_James_Potter
General Thrash
Even some of us Diesel loco drivers are as well... Especially when the fireman on the kettle at the other end of the train keeps on running out of steam at all the wrong moments and you're relying on him to keep the brakes off.
I taught a fireman a very important lesson in keeping the boiler pressure above that needed to create 21in on the vac brake. Got fed up with one of the fireman running out of steam (a regular occurance with a small group of drivers and firemen) on a regular basis so I decided to teach him a lesson.
Coming down the bank at a steady 12mph, I hear the unmistakable sound of brakes beginning to come on... A quick check of the vacuum gauge reveals that the vacuum is dropping and too slowly for the driver (who liked to make quick and hard applications) to have set the brake.
427 in idling/engaged on the rear end of the train with the kettle on the front and both were coasting down the hill with only the steam engine with a touch of power to keep the pistons lubricated with oil.
So the vacuum passes 15in and it's at that moment, I decide we are NOT going to stop. I grabbed 427's power controller, told my secondman to hold on and whipped it open. The engine chucked out the horsepower and started accelerating us against the brake force of the two coaches. eventually, the vacuum balances out at 12.75in Vac and we settle at 14mph with 427 producing about 230 horsepower.
Eventually, we made it down into the next station. I went to the front on the trackside, checking the wheels on the coaches as I went by and found that they were nice and hot for the next stage of my lesson. I called the fireman down from the cab, told him to take off his glove and stick his hand on the nearest coach wheel.
He soon learned two valuable lessons... 1. When looking for hot-boxes or hot wheels, hold your hand above the wheel/axlebox first to see if there is any heat and 2. Never ever run out of steam because the other crew on the train might not look on it favourably.
Having said that, said same fireman was duly removed from the footplate about a month later for lighting a fire inside the steam engine without checking to see if there was enough water in the boiler first. This heated the fusible plug enough to cause it to start dripping and it was only after we got back on the first service the following day that it was noticed. Who did he ask to double check the leak? Me...
regards
Harry
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spiffy --
I'll let others respond to 1.
For 2:
The draft effect from the exhaust steam as it passes up the blast pipe to the chimney makes the fire burn bright, generating more heat. The blast is most intense at speed with full regulator and at full cut-off. When stationary or when moving at slow speeds it may be necessary to use the blower to create the desired blast to keep the fire burning brightly.
Use the N-key to open the blower and Shift-N to turn it off. Again, there is an animation inside the cab.
Phil
I'll let others respond to 1.
For 2:
The draft effect from the exhaust steam as it passes up the blast pipe to the chimney makes the fire burn bright, generating more heat. The blast is most intense at speed with full regulator and at full cut-off. When stationary or when moving at slow speeds it may be necessary to use the blower to create the desired blast to keep the fire burning brightly.
Use the N-key to open the blower and Shift-N to turn it off. Again, there is an animation inside the cab.
Phil
The blower is a steam pipe in the shape of a ring placed somewhere above the steam exhaust from the cylinders and below the chimney vent inside the smokebox. A valve in the cab admits steam from the boiler into the ring. In the top of the ring are any number of vents facing upward. The boiler steam comes out of these vents and shoots up the chimney at great speed. This forces the draught through the boiler and causes the fire to burn brightly. Because a valve controls this process the speed of the escaping steam can be increased and decreased in controllable amounts varying the degree to which the fire burns brightly. In some photos of steam locos sitting at the platform you can see the smoke coming out of the chimney and rising with some force; this is a good indication of the blower at work.
Here endeth the lesson (sorry about that chief) :hehe:
Cheers
Nix
Here endeth the lesson (sorry about that chief) :hehe:
Cheers
Nix
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The reason for and use of the blower has been more than adequately explained by others. However it was also used to avoid any tendencies for the locomotive to blow back.
A blow back describes the reversal of the normal gas flow through the fire, air being sucked down through the chimney, then via the tubes into the firebox. It was not common, but was highly dangerous to the footplate men because flames would shoot out of the firehole door.
Pressure changes at the chimney were a cause of blow back, examples being entering a tunnel at high speed or sudden closing of the regulator. A blowing superheater header or superheater tube also increased the risk of a blow back.
The risk of a blow back was significantly reduced by putting on the blower and closing the firehole doors. So firemen would carry out both of those actions on approaching a tunnel or at locations where the engine would be drifting without steam.
Yeah, this one pops up from time to time...
The train brake works on all cars in a train. The independent brake (spelt independant by Auran :hehe: ) only works on the loco. There is a slight time delay in operation of the train brake to the brakes taking effect which is fine when driving a train where things can be anticipated but is a darn nuisance when you're trundling around a yard or loco depot with just the loco. The independent brake operates much quicker than the train brake but only on the loco. You have to be real careful how you use it on a train because the loco slows down but the rest of the train keeps going. The run in of slack can be a real kicker sometimes (I've seen a lightly loaded wagon get pinched off by this little trick!).
As a general rule (and it's only general) use the train brake when driving trains and never the independent brake, and only use the independent brake when travelling "light loco".
Cheers
Nix
The train brake works on all cars in a train. The independent brake (spelt independant by Auran :hehe: ) only works on the loco. There is a slight time delay in operation of the train brake to the brakes taking effect which is fine when driving a train where things can be anticipated but is a darn nuisance when you're trundling around a yard or loco depot with just the loco. The independent brake operates much quicker than the train brake but only on the loco. You have to be real careful how you use it on a train because the loco slows down but the rest of the train keeps going. The run in of slack can be a real kicker sometimes (I've seen a lightly loaded wagon get pinched off by this little trick!).
As a general rule (and it's only general) use the train brake when driving trains and never the independent brake, and only use the independent brake when travelling "light loco".
Cheers
Nix
Harry_James_Potter
General Thrash
Yeah, this one pops up from time to time...
The train brake works on all cars in a train. The independent brake (spelt independant by Auran :hehe: ) only works on the loco. There is a slight time delay in operation of the train brake to the brakes taking effect which is fine when driving a train where things can be anticipated but is a darn nuisance when you're trundling around a yard or loco depot with just the loco. The independent brake operates much quicker than the train brake but only on the loco. You have to be real careful how you use it on a train because the loco slows down but the rest of the train keeps going. The run in of slack can be a real kicker sometimes (I've seen a lightly loaded wagon get pinched off by this little trick!).
As a general rule (and it's only general) use the train brake when driving trains and never the independent brake, and only use the independent brake when travelling "light loco".
Cheers
Nix
And when they mean light loco, they literally mean a singular loco travelling on it's own with no other loco. a driver of a group of locos multipled up/coupled up together must use the train brake.
regards
harry
I don't know about "crushed" but in the example I quoted above the heavy wagons caused a lightly loaded wagon to "lift" so it became derailed. Mind you, you can also do that by using the train brake very badly!
The nice thing about TRS is that that sort of thing doesn't happen so if you want to run a 4,000 ton coal train at 70 mph and slam the independent brake on full all that happens is that you slow down! If you get a chance to drive a real 4,000 ton coal train I urge you never to slam the independent on like that... :hehe:
Cheers
Nix
BTW if you do a forum search for "independent brake" "train brake" "automatic brake" and so forth you will prolly find a few entries of interest.
The nice thing about TRS is that that sort of thing doesn't happen so if you want to run a 4,000 ton coal train at 70 mph and slam the independent brake on full all that happens is that you slow down! If you get a chance to drive a real 4,000 ton coal train I urge you never to slam the independent on like that... :hehe:
Cheers
Nix
BTW if you do a forum search for "independent brake" "train brake" "automatic brake" and so forth you will prolly find a few entries of interest.