Western Railroad Discussion > Is it possible to push start a GP9?

Let's say you go to work one day and need to start a couple locomotives for a train that day. When you get there, one locomotive starts right up, but the other has a dead battery (not totally dead, but not enough to start). So instead of parking the units next to each other and running jumper cables, you would push one locomotive down the track with the other until it started running on it's own? I suspect that it would only work with older units that have both a DC generator and traction motors, and the basic electrical of a GP9. To prep the unit to start, I imagine you would put the unit in start and prime the engine then switch it back to run and put the reverser in forward so that power generated by  the traction motors will turn the generator which would turn the motor.
  Anyone heard of something like this being done before? I saw a video on youtube where four guys supposedly push started a sizable Russian diesel. That engine might have been direct drive, but at a somewhat higher speed the electrical of a GP9 should like a motor-generator set.  I really don't know the answer myself, and I do not know how certain systems will react under such circumstances. So what are people's thoughts?

Ted Curphey
Ontario, OR



Edited 1 time(s). Last edit at 06/08/15 04:53 by funnelfan.

No.

Bring your jumper cables!

Completely impossible.

I have this image of popping the clutch...
 

A couple of people have said this is impossible, but it's really not.  It is however  extremely IMPRACTICAL.

The thing to remember, is that generators and motors are the EXACT opposites. A motor will turn electrical energy into mechanical energy. A generator will turn mechanicl energy into electrical energy. There are some very complex devices that will work either way. In fact, some power plants will turn their generators into motors to rotate the gas turbines. Then, they will disengage, and re-engage as a generatror.  But, this is not the case on a locomotive.

The traction motor is not wired to produce an electric field. It has to do with the excitation i think. Anyway, even if it did, it would encounter a large 600v generator. It too, would have to be converted to a motor, to turn the diesel.

SO, not totally impossilbe in theory, very impractical in relity.

Oh, good golly, what a theory of bunk. The traction motors have no connection to the starter motor nor the battery circuits in no way shape or form.

The answer is NO.

A GP9 and allEMD locos have a starting motor, it is units SD70 and newer which use the main traction alternator to start the prime mover.

TheGP9 models and many of those later also have an auxiliary generator attached to the prime mover which generates 74 vdc for control voltages, excitation and battery charging. Few locomotives have a Spotting circuit feature which allows the batteries a connection to one traction motor which allows the dead unit to move in either direction a few feet to be spotted for service. There is likely no way to use the spotter circuit to charge batteries or operate the starting motor without doing some serious rewiring in the electrical cabinet. I have never seen a 9 series locomotive with a spotter circuit.

Posted from Windows Phone OS 7



Edited 2 time(s). Last edit at 06/08/15 08:36 by fbe.

WC5f is the only one close.
We also need to look back at somebody who posted about traction motors making the diesel turn faster when the engineer throttled off.
GP9s don't have starter motors either.  But remember, dynamic braking is accomplished by making generators out of the traction motors.

So, doing what is suggested CAN be done, although with considerable difficulty, and only on a locomotive equipped with a main generator, which rules out almost everything made since the mid sixties.

To push start a generator equipped unit, and most of them have a start winding as well, because just the generator isn't strong enough, requires most of the power contactor and reverser interlocks to be bypassed, the motor contactors to be put in parallel to get enough amperage to do any good at low speed, and some excitation put into the motor fields. If the explanation I have been given is correct, from 40 years ago, this can be done by opposing the reverser to the direction of travel.

The comment about starting with an alternator is absolutely incorrect, period.  In the mid sixties when all three manufacturers went to main alternators which can't turn an engine over, all three manufacturers went in different ways to start their engines.  EMD installed two 32Volt Delco automotive starters in series. GE installed a start winding in their alternator.  Alco used a Worthington air starter.  EMD has stayed with their Delcos until the SD90s which have an air start, and GE now uses the auxiliary generator to start.



Edited 1 time(s). Last edit at 06/08/15 10:19 by ExSPCondr.

I never saw a GP9 with a starter motor, unless it was modernized. If I remember, they were turned over with the main generator using battery current.

Posted from Android

Its impossible only because there are a few key things that the locomotive is not wired to do. Here's a cliff notes version as to why.

The traction motors do work as generators, in dynamic braking. They need a excitation field generated by the main gen to work as a generator. This is why older locomotives rev up at various speeds in dynamic. (newer units still use the main gen/alt for this purpose, its just things have become so efficient its not as pronounced)

With the main engine shut off, you can not generate that excitation field. And the TMs wont generate anything power no matter how fast you went. However if you had a means to excite the TMs you could generate the power to spin the main generator. But like I said earlier, the locomotive is not wired to pull this off.

Another note, generally despite the fact a DC motor can be used as a generator and generator as a motor. They are typically designed to do a specific task, and dont tend to do the other well at all. To a extent traction motors work well either way but the main generator was designed specifically to work as one. A a main generator that is simply back fed power to be a motor might not spin at a workable speed, or might not be powerful enough to spin the engine at all.

Now that said, there are locomotives that connect the batteries to various windings in the main gen to start. (GE, both Generator and Alternator units). But again the trick wont work here as again the locomotive is not wired to route power in that way, and you still lack a means to excite the TMs.
 

I recall--years ago--reading about push starting an ALCO RS-1 here at OERM that had been a military locomotive. We have two of them! I didn't pay a lot of attention to the instructions but it said you have to block the starting relays close the battery switch and attain a minimum speed of 3 mph! I would imagine it would be pretty "harry" to try that but in war, you do what you have to do to get running! If the battery is low, sometimes I have disconnected the power piston on the SI governor and had someone crank the starter. Usually if the pumps are at full fuel and you can get the prime mover to roll over at all, she will start! Then you have to reconnect the power piston with the engine running!--Fun! DO NOT ATTEMPT THIS AT HOME!!!!!

Mr. Carr, unfortunately you are half mistaken.  First off, it is Fairbanks-MORSE, not Morris as in Morris Garage or MG.

Secondly, Fairbanks Morse was out of business at least 20 years before a large alternator was manufactured, so the thing connected to the engine was a DC generator as you said in your first sentence, NOT an alternator as you said near the end.

I would suggest you look at the alternator installed on Chrysler products since 1961, and on the rest of the American cars by 1965, and you will see that the large output wire of the alternator is directly connected to the battery all the time!
Please also look at the armature wire of an earlier generator equipped car, and you will discover that this wire is connected to the reverse current relay in the voltage regulator.  This prevents the generator from discharging the battery by trying to turn when the engine is not running.
 

>The traction motor is not wired to produce an electric field.

It better be or it won't rotate as a motor (and you mean "magnetic field").

>It has to do with the excitation

In dynamic braking the traction motor fields are "excited", although from a source separate from the armature circuits.

>A GP9 and allEMD locos have a starting motor, it is units SD70 and newer which use the main traction alternator to start the prime mover.

F-units, GP-7, GP-9, SD-9,  SW-1500, and all early DC drive diesels had starting windings in the main generator, not starter motors. When EMD went to AC-DC drive, they began using two starter motors per engine, wired in series and engaging the same flywheel.

GE AC-DC drive locomotives (Dash-8s, etc.) use solid state phase/frequency modifiers to crank the main alternator, and it sounds like EMD might be following suit.

>We also need to look back at somebody who posted about traction motors making the diesel turn faster when the engineer throttled off.

For the traction motors to cause this is an urban RR legend, on the part of both RR employees and railfans.

>To push start a generator equipped unit, and most of them have a start winding as well, because just the generator isn't strong enough, requires most of the power contactor and reverser interlocks to be bypassed, the motor contactors to be put in parallel to get enough amperage to do any good at low speed, and some excitation put into the motor fields. If the explanation I have been given is correct, from 40 years ago, this can be done by opposing the reverser to the direction of travel.

Correct, although wildly impractical to accomplish.

If a series wound motor (a traction motor) is turned in a direction opposite to that which it is conneccted to run as motor, it will generate. Same is conversely true for a DC generator. The trick is to jimmy the control apparatus in the locomotive to make connections not normally made (not to mention being sure the engine cranks in the correct direction of rotation).

Edited to add:

A few comments:

>The traction motors do work as generators, in dynamic braking. They need a excitation field generated by the main gen to work as a generator.

Last time I checked, TM excitation was from the Aux Generator, but it's been a while.

>This is why older locomotives rev up at various speeds in dynamic.

The engines sped up in order to provide power for the traction motor blowers.

>With the main engine shut off, you can not generate that excitation field. And the TMs wontgenerate anything power no matter how fast you went.

Of course they will, and if connected to a load, current will flow (completely unregulated). It's called "residual magnetism". How else do you think putting the reverser in reverse while the locomotive is moving forward causes such a rough retardation force (that is until the motors suffer sudden catastrophic failure)?

>I would suggest you look at the alternator installed on Chrysler products since 1961, and on the rest of the American cars by 1965, and you will see that the large output wire of the alternator is directly connected to the battery all the time!

Thanks to the magic of diodes  .  .  .



Edited 1 time(s). Last edit at 06/08/15 11:15 by EtoinShrdlu.

Ted,

Talk to your boss about equipping your fleet with the small diesel Hotstart from over in Newport. These monitor outside temp, water temp and battery condition and fire up to keep all these in start up ready condition. They can be slid into the compressor area on a pallet if the original locomotive is traded off.

While these can be somewhat expensive the State of Washington might subsidize the cost to reduce emissions and idling noise. California is big on this and MRL got the state of Montana to help install Hotstarts in their entire fleet of nonACe locomotives.

The Hotstart system will not support the electric cab heaters so the cabs will still be cold in the winter until you get the engine running.

Posted from Windows Phone OS 7

Interesting discussion....! Never considered doing this because we always jump start a dead unit with our welder.

However, seems to me on a unit with dynamic brakes you could put the dynamic brake transfer switch in the dynamic position; disconnect the battery leads and jumper the leads that go to the dynamic brake resistors to the battery side of the starting contactors. Furnish dynamic brake excitation as in dynamic and push the unit to generate curent while holding in the starting contactor switch.

This would be all and good EXCEPT you normally need air (on older units) to work the Brake Switch and battery power for excitation which you dont have with a dead battery!

Keep the theories coming...again...interesting discussion!

Guess we'll just keep the welder handy!

Dick Samuels
Oregon Pacific Railroad

 

 To all of those Naysayers: If you folks knew ExSPCondrs background you wouldn't even argue the point.





V

SLOCONDR

will Wrote:
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> I have this image of popping the clutch...
>  

I had the same thought.  How many hostlers would it take to push it anyway?  They can just hope there is a slight downhill grade REAL close.

John

I remember working third trick as a hostler at Bayshore and having this conversation with the RH Foreman back in 69. He grabbed a set of prints off the shelf and showed me or I should say tried. I don't know what type of unit it was.

The way he described was coupling the unit in multiple with others and taking off down the track This was before computers and such. It boiled down to wood blocks and paper cups. He would have a volt meter hooked up and when it got high enough he knew which relays to block in.  It is possible, but not worth the trouble. Just grab some heavy arc welding cables and jump it.

I have seen a RH guy run an engine from the jumper cable end, no problem. Those guys (old heads) had a lot of stuff  in their bag of tricks. Even when we had to put an SP unit on the point of ATK and the OS would trip at 68. No tools, everthing was right in the cab.


Nudge



Edited 1 time(s). Last edit at 06/08/15 12:26 by spnudge.

As stated elsewhere, early ALCOs can be push started. The Maintenance Manual for S1 to S4, RS series locomotives included, very clearly outlines the procedure for accomplishing this. I would imagine you could follow the same procedure on an S6 series as well, but I have yet to get my hands on an S6 manual despite my best efforts. The procedure probably came in pretty handy when out in the field, and you had one unit running, and one that would not start, jumper cables were not always handy. While some say it was "wildly impractical", sometimes you had to do whatever it took took keep the railroad running. The procedure would only take a few minutes, waiting for jumper cables or towing to somewhere that had the ability to jump a unit could take hours.

Posted from Android

Here's the smarter way to start a diesel--this was at the west side of the long vanished Santa Fe San Bernardino Shops.  If a locomotive had been in the shop for a while and the battery had discharged to the point where it wouldn't start the "mill", the battery on the cart in the lower right side of the photo would be used for a jump start.  Note the heavy cables long enough to reach the battery on just about any unit.

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