traction motor, caution, contains amateur photos.

[edblysard]

First photo is the inside or rear of the motor, this faces inward towards the center bolster.

The two ears or studs hold the traction motor against a stop, which keeps it from spinning on the axle.

Look at them, come up with questions and comments.

[Paul of Covington]

   Thanks for the pictures.    I'm always interested in mechanical details.

    On the first photo, you mentioned that the rear of the motor faces the bolster.    Is this the practice on two axle trucks?    I seem to remember reading some years ago that three-axle trucks had switched to having all motors facing the same way to make the tractive force of each one more equal or something like that.     Am I right or wrong on either of these statements?

[edblysard]

Two will face one way, with an odd man out on a three axel truck, the other truck will be opposite, keeps the tractive force somewhat spread evenly across both sides.

On a B truck, or two axel truck, each motor powers the opposite side.

If both have the stop tabs towards the inside, the "front" motor will power the left front and the "rear" motor will power or gear up on the right.

Let me look and see if I have a photo from higher up, it might show the pair in a rebuilt truck and let you see the way they are positioned.

[edblysard]

More traction...

And you thought your floor jack was bad....

Paul, no go on the other photo, either on my old computer or lost in space!

[Firelock76]

Did I see "Pullmor" stamped on that motor or my eyes playing tricks on me?

[Modelcar]

....Good visuals of traction motors and their environment Ed.

Like the "bumper jack" too.

[edblysard]

Firelock,

I will look tomorrow, we have a whole bunch of "new" rebuilt motors in the shop, shrink wrapped, I will go check one and see what the tag says.

[CShaveRR]

I think it was a joke, son!

I was looking to see some armature photos, but these looked pretty good!

[K. P. Harrier]

In the first series of photos, the second and fourth photos, are those wires to spark plugs? (Hehehe.)

Seriously, great photos, Ed!  Thanks for sharing.

 

[edbenton]

Nop that would be 4/0 cable used to feed teh Brushes in the TM 2 Positive 2 Negative.  But when you have 1500 AMPS at 600 volts DC you better have some HEAVY CABLE.  Put it this way You not going to wire this thing with 18awg stuff we use on any Layouts we have at home or 10/2 Romex like that is in our house.  You might find some 12 gauge wiring in the Control panels and relay panels but the Heavy cables are a Minimum of 2/0 and heavier. 

[Randy Stahl]

Thats 535 MCM cable.

The two leads on the left are armature leads "A" and "AA" The "A" lead goes to the brushgear then through the interpoles and exit the motor on the "AA" lead. Then the "AA" lead goes to the braking contactor and then to GN.

The two leads on the right are the "F" and the "FF" leads. "F" and "FF" leads come from the reverser contactor other wise the motor could only run in one direction.

 

Randy

[NP Red]

In photo #4 are the two "ports" at the bottom of the photo for cooling air?

 

[Mookie]

I'm sure this has been asked - on forum or in Trains, but since I can only learn in small bytes....

The new process of 2 traction motors vs 3 - doesn't this limit the ability of the locomotive to be used on different terrains?  Or are they just on unit trains that go over the same territory all the time? 

[Randy Stahl]

I think what you are looking at is the oil well for the traction motor support bearings. The traction motor cooling is from the top left with ports around the right side for the 4 air outlets. You can see one outlet towards the top of the picture, there's a small bit of safety grating over the opening.

randy

 

[Firelock76]

Maybe I shouldn't be, but I'm amazed at how much power is in such a small package.  What are the dimensions of those traction motors, they look like they can't be more than 3.5 feet across the axle?

[Norm48327]

1500 amps at 600 volts says each traction motor is capable of producing 1200 horsepower.

I'm certain the never approach that in service or they would be toast in short order.

[Paul_D_North_Jr]

746 or 750 watts per HP.

They do approach that 1,500 amps in service - that's what the "red zone" short-time rating is all about.  But at that level, though, it has to be for only 5 minutes or less - or yes, "they would be toast in short order".  More typical would be around 940 amps max. continuous which would yield 750 HP per motor, or 3,000 HP for a 4-motor unit.   

Someplace here a while ago it was stated that the 600 volts is not fixed but is just nominal, and could vary quite a bit - perhaps by the series ==> parallel transitions of the motor wiring configurations, etc.  Anyone have confirmation, correction, or more details on that ?

- Paul North. 

[oltmannd]

Voltage in a GP40-2 at 70 mph is going to be around 1200-1300VDC.  How high you can go is limited by the rating of the diodes.  The rating climbed from about 1000 up to 1300 volts from 1965 to about 1980.

In order to avoid high voltages and still put out HP at speed, you had to resort to shunting some of the fields in the traction motor stator.  GP30s, 35s and early 40s had some steps of field shunting.

[edblysard]

Our gauge in the control stand has 1900 amps short term for 5 minutes, I think.

I will snap a photo tomorrow for you all, but I bet Randy knows.

Our locomotives are rated at 1500 HP each, Cat power for the prime.

Firelock, shame to say, they are not Pulmor, but RPI...was hoping for RIP but alas...

Note in the photo of the old motor, which has 15 years on it, the two round hatches in the gear cover.

I don't know for sure, but I guess they are for both inspection and lube.

NP Red, the two square holes are as Randy said, take his word on any of this stuff, it's what he does for a living, plus a lot more wrench turning that I ever want to do!

If I get the chance I will get a shot of the cooling duct intake, its on the other side from all of this.

I think you can see some of the contactors Randy talks about inside the duct, if I remember correctly, we will see.

[WSOR 3801]

More amateur photos:

GP swing hanger truck, without traction motor.  We just set them in the mud while the combo gets changed out.

Better view in daylight.

On 6-axle EMDs since 1972 (excepting Conrail SD40-2s and SD50s) all three motors on each truck face the same way.  Pulls better that way.  With one going the other way, there is a lifting-twisting force involved, which unloads the truck slightly and causes wheelslip when trying to get a heavy load started.  With all 3 motors going the same way, the truck digs in better, less weight transfer.   

Our MP15ACs are rated 920 amps continuous, 1150 short time.  These units are a bit light, so they spin out before they get near short time rating.  The GP38s and SD40s are 1050 amps continuous, better cooling of the motors.  Continuous ratings are in notch 8, lot of cooling air moving around at that notch.

I have seen 1500 amps when trying to get too much tonnage started.  After a little bit you can smell the impending arrival of the train.

 

 

[Randy Stahl]

As Don said , 600 volts is nominal. When a motor is at a stand still is effectively it is a direct short, high current, zero voltage. When the motor begins to turn , then the voltage rises with the speed. Voltage is limited by the GV module. The diodes we are using are 2400 volt diodes in the rectifier. 2400 volts is enough to destroy the cabling. The motors have voltage limits which usually determine the maximum generator voltage setting in the cabinet. The GX (generator current module) Sets the maximum current and the ELR (excitation limit relay)  is the secondary current protection.

The contactors and reversers are in the locomotive electrical cabinet. Reversers are identified by the coated copper crossover bus bars on the top of the contactor, braking contactors do not have the bars on the top.

I was never a big fan of field shunting, the settings and amount of moving parts was depressing.

Randy

[Anonymous]

It is interesting to see the details of the anti-rotation stops for the traction motor.  You can see the two cast lugs on the motor case in Ed’s first photo, and the corresponding feature on the truck bolster that those lugs engage in the second photo posted by WSOR above.  It looks like there is a stack of rubber cushions built into the feature on the bolster. 

 

I wonder if that anti-rotation feature is known to have ever failed by breakage.  I suspect that it is designed so that even if there were a break, the motor would crowd into the bolster and be prevented from rotating down to the point where it would jam into the ties.  

[Randy Stahl]

Bucyrus

It is interesting to see the details of the anti-rotation stops for the traction motor.  You can see the two cast lugs on the motor case in Ed’s first photo, and the corresponding feature on the truck bolster that those lugs engage in the second photo posted by WSOR above.  It looks like there is a stack of rubber cushions built into the feature on the bolster. 

 

I wonder if that anti-rotation feature is known to have ever failed by breakage.  I suspect that it is designed so that even if there were a break, the motor would crowd into the bolster and be prevented from rotating down to the point where it would jam into the ties.  

 

Traction motor nose supports. I have seen them break and yes they will jam up against the truck frame. Worst case scenario is that a lug breaks and the the front of the motor falls on the ties.

The traction motor nose support spring pack and the motor nose supports have to be checked on periodical inspections for clearance, we allow no more than 1/4 inch. There are hardened steel wear plates for this application.  Traction motor spring packs are removable and rebuild-able.

[Anonymous]

Randy Stahl

Traction motor nose supports. I have seen them break and yes they will jam up against the truck frame. Worst case scenario is that a lug breaks and the the front of the motor falls on the ties.

If a lug breaks and the motor falls down onto the ties, could it snag on the ties and derail the truck by the motor "pole vaulting" the truck upward? 

[Randy Stahl]

Bucyrus

 

Randy Stahl:

 

 

Traction motor nose supports. I have seen them break and yes they will jam up against the truck frame. Worst case scenario is that a lug breaks and the the front of the motor falls on the ties.

 

 

 

If a lug breaks and the motor falls down onto the ties, could it snag on the ties and derail the truck by the motor "pole vaulting" the truck upward? 

I.E. train wreck ....

[rrnut282]

Firelock76

Maybe I shouldn't be, but I'm amazed at how much power is in such a small package.  What are the dimensions of those traction motors, they look like they can't be more than 3.5 feet across the axle?

Then you should be floored by a steam locomotive.  In most cases all their power is generated in a two spaces of around 32"x28". 

[rrnut282]

Mookie

I'm sure this has been asked - on forum or in Trains, but since I can only learn in small bytes....

The new process of 2 traction motors vs 3 - doesn't this limit the ability of the locomotive to be used on different terrains?  Or are they just on unit trains that go over the same territory all the time? 

Are you referring to BNSF's purchase of 6 axle AC units with only 4 traction motors?

[Mookie]

rrnut282

Mookie:

I'm sure this has been asked - on forum or in Trains, but since I can only learn in small bytes....

The new process of 2 traction motors vs 3 - doesn't this limit the ability of the locomotive to be used on different terrains?  Or are they just on unit trains that go over the same territory all the time? 

 

Are you referring to BNSF's purchase of 6 axle AC units with only 4 traction motors?

yes. 

[BamaCSX83]

Wow, this answers a lot of questions for me.  Thanks to all whom have not only posted pictures, but also have helped out on the technical aspects of the traction motors.  I've always wanted to see one out and up close and now I have, thanks again!

[Firelock76]

To rrnut282:  Oh, I AM floored by steam locomotives!  Steam rules as far as I'm concerned.  High-pressure steam pushing a piston is something I can easily understand.  High torque in a small package like a traction motor is what surprizes me, and then using that torque to move a heavy train without blowing the motor.