I think it's worth pointing out that there are two sets of connections between locos MUed directly in a consist: electrical and air. The 27-point electrical connection is higher up. The air hose connections are on the pilots. The air connections deal at least with sanding control, and I think the locomotive independent brake (as opposed to the train line air).
wjstixIt's easier to understand if you remember 'diesel' locomotives are really 'diesel-electric' locomotives.
the question came to mind while recently watching "Unstoppable" (i assume this was discussed years ago when the movie came out). The thought in the back of my mind was NASA's digital fly-by-wire, Computers Take Flight, which ocurred while the space shuttle was being developed.
while fly-by-wire provides the benefits of a less expensive and lighter control system, and computers enabling new flight control features including the control of less than stable aircraft (e.g. F-16), they also allow more reliable remote operation. I believe NASA needed a way to return the shuttle if all crew members were incapacitated.
So I am not surprised that pajrr says "Lots of yard switchers are radio controlled" and thought that if the space shuttle, which is now retired, could be remotely operated, why not a train. (Of course remote access to the locomotive should be no less secure, if not more than when we send private info (e.g. credt card #s) over the internet).
greg - Philadelphia & Reading / Reading
It's easier to understand if you remember 'diesel' locomotives are really 'diesel-electric' locomotives. The diesel engine(s) generate electricity, and the electricity powers the electric motors in the trucks that turn the loco's wheels. Multiple-unit running of electric engines existed before diesels, so diesels had a model to follow.
jrbernier Greg, Standard Multiple Unit(MU) controls are done using a 27 point cable between the locomotives. Remote 'in train' locomotives are controlled by Distributed Power Management(DPU) from the lead unit. The lead unit can shut them down if needed, and they will automatically go off-line if there is a signal loss. I am not sure what the current security/encryption features are, but I syspect when the initial DPU is set up in a terminal, some kind of encryption cipher may be enabled. Jim
Greg,
Standard Multiple Unit(MU) controls are done using a 27 point cable between the locomotives. Remote 'in train' locomotives are controlled by Distributed Power Management(DPU) from the lead unit. The lead unit can shut them down if needed, and they will automatically go off-line if there is a signal loss. I am not sure what the current security/encryption features are, but I syspect when the initial DPU is set up in a terminal, some kind of encryption cipher may be enabled.
Jim
When communication is lost with a Distributed Power consist, the DP will continue following it's last command for up to 90 minutes in power. If comm isn't restored by then, they will go to idle. In dynamic braking, the DP will continue until comm is restored. There are ways to override a DP when out of comm by using air brake applications.
Jeff
As far as no one on board controlling a train, has anyone been to a major yard? Lots of yard switchers are radio controlled. The yard conductor runs the train from the ground with a lunchboxed sized controller like a model airplane. The conductor stands at a turnout, runs the train past so it clears where he is, he throws the turnout and runs the train past him in the other direction. It is a one man operation. Like a full sized DCC model railroad.
Modeling BNSF and Milwaukee Road in SW Wisconsin
Individual units may or may not have controls - or there may be controls in a car that isn't itself a locomotive. The connection between coupled units, and the length of the train in a passenger 'push-pull' operation, is by MU cable - a direct electrical connection.
Where freights have distributed power, the in-train units are controlled by radio from the head-end cab. Only one unit will have radio control. The other unit(s) will be connected to it by cable.
I may be wrong, but I believe that direct input from the on-board control stand will override a radio input from outside. Having some person not on the locomotive being able to override the on-board engineer strikes me as a REALLY BAD idea. OTOH, Automatic Train Stop devices can, and will, override the engineer to the extent of dumping train air if the locomotive tries to pass a signal set to Absolute Stop.
ATS isn't exactly new. Noo Yawk subway cars older than I am had it - and I've been drawing Social Security for a while now.
Chuck (ex Noo Yawka 2500 miles removed)
curious. i assume multiple engines in a consist are controlled by the engineer in the lead locomotive.
1) is control/communication between locomotives an electrical connection? (could be radio link)
2) is there any possible way the consist could be controlled by radio (overriding what an engineer might be doing, if an engineer were present)?
also curious how individual and consisted diesel locomotives are controlled