When a train with DPUs sands the rails for the front locomotives, do they have control to determine if/when the DPU also releases sand.
Do the DPUs have an automated control to dispense sand when necessary (wheel slip)?
As far back as 1974, the Milwaukee Road version of Locotrol had an on-off sanding switch control for the DP, operating 'in the direction of travel'. This displayed a flashing yellow "sand on" light. If the DP suffered wheelslip, its wheelslip alarm would trigger, but the response was not automatic: the sanding switch would have to be "placed in the ON position" (and then turned off manually when no longer wanted).
Now, by 2005, GE was tacitly incorporating sand into its determined 'Dispatch Adhesion' of 27%, and it was further well understood by that time that locomotives that were allowed to slip and then 'sanded' could suffer considerable damage. The current version of sanding is interestingly highly computerized -- see the description of controller EKK0030, running SSMS 4.0, for example -- involving no less than 14 digital control and configuration inputs, and 6 backchannels for status and error communication. GE also notes prominently in literature for this controller that it can operate 'standalone' once configured, as well as be operated relative to other units.
Newer units are supposed to sand automatically when they start slipping, though I think it is debatable as to how well this feature actually works.
There is a manual "remote sand" button on the DP control screen.
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The auto sanders usually seem to wait too long. Our modern EMD, and now some of the newest GE* engines won't manual sand until you are below 10 or 12 mph. All you can do is listen to the wheels "singing" on the rails as they lose traction.
The same for DP engines. There is a manual sand button, but it may not work. There is a screen indication of which consist(s) are sanding.
Jeff
SD70DudeThere is a manual "remote sand" button on the DP control screen.
How we'll do the mechanical forces perform at actually keeping sand in the locomotives and the sanding tubes clear?
adkrr64 It varies. A little independent brake can help control wheel slip when sand is not available. GE U25's did that automatically as part of their wheel slip system. SD70Dude There is a manual "remote sand" button on the DP control screen. How we'll do the mechanical forces perform at actually keeping sand in the locomotives and the sanding tubes clear?
It varies.
A little independent brake can help control wheel slip when sand is not available. GE U25's did that automatically as part of their wheel slip system.
SD70Dude There is a manual "remote sand" button on the DP control screen.
mvlandsw adkrr64 It varies. A little independent brake can help control wheel slip when sand is not available. GE U25's did that automatically as part of their wheel slip system. SD70Dude There is a manual "remote sand" button on the DP control screen. How we'll do the mechanical forces perform at actually keeping sand in the locomotives and the sanding tubes clear?
Sanders are a part of the Engineer's 'Calendar Day' inspection that is to be perfromed on each locomotive each calendar day. Sanders not working is grounds for Shoping the engine until such time as the sanders are repaired.
Never too old to have a happy childhood!
BaltACDSanders are a part of the Engineer's 'Calendar Day' inspection that is to be perfromed on each locomotive each calendar day. Sanders not working is grounds for Shoping the engine until such time as the sanders are repaired.
It's a little more involved than that.
9 pages about sanders. Not as dry as some other books I've read.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
zugmann BaltACD Sanders are a part of the Engineer's 'Calendar Day' inspection that is to be perfromed on each locomotive each calendar day. Sanders not working is grounds for Shoping the engine until such time as the sanders are repaired. It's a little more involved than that. 9 pages about sanders. Not as dry as some other books I've read.
BaltACD Sanders are a part of the Engineer's 'Calendar Day' inspection that is to be perfromed on each locomotive each calendar day. Sanders not working is grounds for Shoping the engine until such time as the sanders are repaired.
How long and the approximate wheel speed would the wheels have to spin in place for that to happen? If that's now answerable, would spinning the wheels at 35MPH (equivalent) for 2 minutes be able to do that?
...ok?
BaltACD
zugmannNot as dry as some other books I've read.
Hopefully the sand is good and dry...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Perry Babin How long and the approximate wheel speed would the wheels have to spin in place for that to happen? If that's now answerable, would spinning the wheels at 35MPH (equivalent) for 2 minutes be able to do that?
You may have read about that incident in Middleton's When The Steam Railroads Electrified, though that may have also shown up in a TRAINS article. The book mention that the rails had been worn down to the webs. One thing that roved was that three phase induction motors are rugged beasts.
CSSHEGEWISCH Perry Babin How long and the approximate wheel speed would the wheels have to spin in place for that to happen? If that's now answerable, would spinning the wheels at 35MPH (equivalent) for 2 minutes be able to do that? I remember reading in TRAINS many years ago about a three-phase electric (constant-speed motors) on GN in helper service that pulled a stunt like that in the Cascade Tunnel. The motors continued turning at their constant speed even after the train stalled and the crew didn't realize that something was wrong until they noticed that they hadn't reached the tunnel portal in the usual time.
Which begs the question - How long had the crew been asleep? Even in a tunnel a crew has sight of things that indicate whether the train is still in motion or not.
BaltACDWhich begs the question - How long had the crew been asleep? Even in a tunnel a crew has sight of things that indicate whether the train is still in motion or not...
That said, there are some surprising examples of what looks like ignorance that probably isn't. One example was the forward-engine slipping on PRR T1s: the exhaust and mechanical noises were relatively unheard back in the cab, there was little or no undue vibration, and there was no way to 'trim' the slipping engine separate from the other one. Another is the story from Trains, long ago now, involving something closer to your heart: a B&O passenger train with then-new EA power having to detour over the New York Central high-speed main As the story went, the NYC guy did the condescending 'this is a high-speed railroad and we expect you to get this train over the road'. The B&O engineer, a quiet type, said nothing but opened his throttle. "Unaccustomed to the smooth ride provided by the diesel" the NYC pilot sat unawares until he looked over and saw something like 103mph -- he was not delighted in any respect.
Overmod BaltACD Which begs the question - How long had the crew been asleep? Even in a tunnel a crew has sight of things that indicate whether the train is still in motion or not... You're saying 'the Thing That Is Not To Be Said' -- you'd certainly never hear a crew 'confess' to being asleep, either in a company discipline hearing or an outside investigation. ...
BaltACD Which begs the question - How long had the crew been asleep? Even in a tunnel a crew has sight of things that indicate whether the train is still in motion or not...
You're saying 'the Thing That Is Not To Be Said' -- you'd certainly never hear a crew 'confess' to being asleep, either in a company discipline hearing or an outside investigation.
...
Having conducted a number of railroad 'Investigations' I know many of the things that can never be 'testified' about.
I recall reading an anecdote some years ago (I think it was the NYC) about a DE locomotive cruising along, with one axle merrily spinning away with no regard to the actual speed of the locomotive...
This is one of those things that will get rapidly and progressively worse the longer it goes. A brief spin may leave a divot on the railhead. As things heat up, though, it will progress quite rapidly.
We have a spot on Big Moose grade where a six axle obviously spun for a bit. It's more like a rumble strip, though.
tree68I recall reading an anecdote some years ago (I think it was the NYC) about a DE locomotive cruising along, with one axle merrily spinning away with no regard to the actual speed of the locomotive...
We've had engines with bad wheel slip sensors/cards/whatever that will just rooster tail sparks under the slightest load.
Extra fun when it's part of a remote set where nobody can directly monitor it (and it doesn't trip any faults with the controlling motor)
Some wheel slip detection systems work by comparing the speed of the axles to each other. If they are all spinning there is no difference to detect and the wheels can spin quite fast.
An engineer who ran steam engines told me that when the smoke in a tunnel got too thick to see anything they would hold a broomstick against the tunnel wall to feel if they were still moving.
There was a story of a lad that stopped to watch a PRR 2-10-4 stall that chewed up the rails in the same way.
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