How do train engines pull each other? does the first one controll the others? what if one is backward?

Question

how do they pull each other? i saw one all by itsself in the back and it still was giving power.....how does that work?

does the main train controll the other and the speed?

PLEASE HELP IN DETAIL WITH THESE QUESTIONS

Answer 1

some are radio controlled and some use inter connecting valves that run under and connect to each car so all has to be done is change the settings from the lead car

Answer 2

Engines get pulled to destinations just like the cargo trailers. The engines that run up front are all controlled by one unit and engineer. The engines are electric that get there power from diesel engine generators. Just like most electrical motors you can run them forward or backwards. This helps them slow the train down by reversing the electricity.

Answer 3

if the trains are really long they will have a engine in the middle and back to hel push or pull

Answer 4

ong story Short, The lead Engine in which the Engineer is on will pull the other Eng unless both are under power, the Engr in the  lead Eng tell other Eng what to do

Answer 5

In detail we can do.

An "engine" was once defined as, "A unit propelled by any form of energy, or combination of units operated from a single control, used in train or yard service."  It has been revised over the years, but this is the best description I have encountered.

The diesel electrics of the last 60 years have all had the capability for "multiple unit operation" which is simply called MU operation.  It is actually a simple set up, where the controls for electrical systems, including control of power and dynamic brake, and pneumatic or air-brake systems and other simple connections.  The best way to describe how the units are MUed,  is  to start from the top down when looking at the connections between each locomotive (it is also a good way to prevent overlooking a connection when separating equipment).

The first thing you come to is the safety chains, which are exactly what the name says.  The next is the end plate on which to walk.

Next is the MU cable, often referred to as a "jumper cable", but it is not what you use to jump a dead battery.  This makes the electrical connections between the locomotives.  They are a "multi-pin" affair with different pins or pairs of pins carrying electronic signals or information.  This allows whichever the controlling unit in the consist is to operate the rest as one.

For historians and purists, the first dynamic brale systems were "field loop control" type, which required a second, separate cable between the locomotives.  This was a "taper" dynamic system.  The antiques of today were once much appreciated.

Control includes power throttle position, dynamic brake set-up and control, engine run, control and fuel pump, generator field, fuel saving devices, directional control, headlight control as well as alarm systems that warn of hot engine, wheel slip, dynamic brake over-current, pinion slip or other alarms.

Each engine in the consist receives commands from the controlling unit in this fashion.  However, each unit in the consist has an isolation switch that, when switched to "off line", allows the locomotive to just tag along, whether it is on the point, somehwre in the middle, or on the rear.  In additon, each unit has a dynamic brake cut-out switch the will allow the locomotive to work power, yet not result in "per axel of dynamic brake" restriction.

Next is the coupler.  This is also a self explanatory term.

There are at least four air hoses that allow the units to operate as one as well.  These are the "brake pipe", which carries the air for the brakes on the cars, the engine air-brakes, or "BC equalizing pipe", the "actuating pipe" and the main reservoir air line.

Just as units in the consist can be cut-out for power or dynamic brake needs or restrictions, the control valves for the air-brake systems can be cut-out on each locomotive as well, leaving the controlling unit to operate all from the engineer's seat.

Direction of the units is immaterial, since they work equally well in either direction.  They don't work well cross-wise, however, which makes it a thing to be avoided.

If you are seeing more than one "engine", such as one or more locomotives further back in the train, then these are either "helper engines", which push/pull tonnage to reduce the amount of force on the draft gear of the equipment near the front of the train, or a dangerous method of operation referred to as DPU, or distributed power units.

Helper engines are manned.  DPUs are not.  They are radio controlled.  They are dangerous.  If radio communication is broken or interfered with they will go into "over-ride" and continue to work at the last command they received for a pre-determined length of time before shutting down.  How about 15,000 plus horsepower running in full throttle for a time with no way to shut it down short of an emergency application of the brakes?  Of course the companies that run these bombs waiting to explode will never tell of that.  If the public only knew...................

There is much more detail available on these and other topics if you visit my Yahoo 360 from this site and check out the blogs posted there.

Good question.  Thanks for asking.................

Answer 6

First the Engines are Diesel and they run Generators to power the Electric Motors on the wheels. The Trains are interconnected with a Cable to transfer information from the Main Control car. In some Countries they are actually beginning to use a Train setup that has no people on board and is computer controlled.

The link is "How stuff works" you may learn more reading there, than me trying to explain this.

Answer 7

To put it basically (with two locos moving forward):

There is a 'forward' wire and a 'reverse' wire.  These wires run front front to back of any locos coupled together.  In the cab facing forward with the driver, the forward wire is energised.  This wire runs to the back of this loco where the wires cross.

The forward wire thus becomes the reverse wire (which is now energised).  This is so because the rear cab is running backwards.  Then between locos, the wires cross again.  The reverse wire then becomes forward as the cab of the coupled loco is moving forward.

Hope this makes sense - and helps!

Answer 8

The power control is via the jumper cables HOGHEAD mentions.

Diesel Electric locomotives have two basic electrical systems, the control system--low voltage (48 vdc?)-- and traction system--high voltage (over 2000v).  I’d say there’s two more systems, the AC for the cooling fans, and the dynamic brake, but they’re interconnected and share components depending on the set up.

Control wires are run through each unit.  There are 27 of these wires. The control systems connected to these wires are considered “trainlined.”  They start at the MU receptacle in front, and the receptacle wires are connected to a terminal board.  From the front terminal board, they run to the main electrical cabinet which is the back wall of the cab at another terminal board.  From that board, they run to board near the rear MU receptacle,  where they connect to the wires from the rear MU receptacle.    

The 27-wire MU jumper is connected to the next locomotive.

Back at the electrical cabinet.  The controlling system of the lead locomotive energizes whichever circuit is needed to command itself.  The connections at its electrical cabinet to the “trainlined wires” send the appropriate commands to all other locomotive so connected.   In the “trailing” locomotives, this is the same point where the trainlined wires command the trailing locomotives.

The trainlined wires we will discuss here are,  +dc, -dc, control & fuel pump, Main gen, forward, reverse, and governor A,B,C,D.  (A is +1, B is -1, C is +2, D is +4)

The diesel power plant turns a main generator which produces the traction voltage.  The rpm of the power plant is controlled by a governor, and had seven speed settings.  The governor controls the excitation of the main generator to produce an amount of power for each setting.

When a collection of locomotives is put together, and they all are running, after all connections are made,  the control and fuel pump (c&fp) switches are turned off on all but the first locomotive, and all the Main Gen switches are turned off.

At this time the c&fp switch on the lead locomotive is energizing the control system and feeding power to the fuel pump of itself, and through the trainlined wires, the control systems and fuel pumps of all locomotives.   If it is turned off, all will shut down as the fuel pumps will stop.

When the engineer starts to move the consist, first, she’ll turn on the Main Gen switch, which will enable her throttle to excite the main generator.  The trainlined wire, will close switchgear on each trailing locomotive to be excited.

She sets the locomotive to “forward,” and the switchgear in her locomotive then set to provide power to the tracion motors to move the locomotive forward.  Since the forward wire is trainlined, the switchgear of all locomotives is also set.  No traction power is produced yet.

When she pulls the throttle to notch 1, the throttle then energizes a circut to command the governor to excite the Main Genenerator, and it is also a trainlined wire, the governors of all locomotives excite the generators, and all locomotives are starting to produce power and trying to move, (and will if the brakes are released).  The diesel engines have not increased rpm yet.

At notch 2, the A wire is energized, and all governors step up the rpms one setting and more exication.   Each notch increases rpm and excitation, all the way to notch 8, which is full power.

Now, your question about direction.   The “forward” and “reverse” wires are crossed in the MU jumper.  They are also crossed in the locomotive from the front MU receptacle to the front terminal board. If the second locomotive is backward, it’s “reverse” trainline wire is energized, not the “forward.”

The combination of the crossover in the jumpers and at the front terminal boards is what makes it work.