Adding the padding

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Adding the padding
Posted by Murphy Siding on Saturday, January 16, 2016 10:56 PM

     The current issue of Trains Magazine shows that some railroads order new locomotives with 16,000# of ballast.  Where, and how is this added?  It's noted that the ballast gives the locomotive better traction.  Where would this be needed? Doesn't carrying around an extra 16,000# have a downside?

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Posted by ericsp on Saturday, January 16, 2016 11:27 PM

I don't know what they use for the ballast or where it is added. Adding weight does mean more energy is required to move the locomotive. However, if the locomotive is pulling trains that don't move fast, then more of its power can be used for pulling. It will need more weight on the wheels to increase the frictional force between the wheels and the rails. This means the same amount of locomotives can pull more cars, or they may be able to use one less locomotive for a particular train.

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Posted by NorthWest on Sunday, January 17, 2016 12:12 AM

Generally, weight is added by simply using thicker steel when constructing the frame, though it may also be added in other areas. The key is to keep the locomotive balanced.

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Posted by beaulieu on Sunday, January 17, 2016 12:39 AM

The downside is less than the upside.  More weight allows the locomotives to pull harder at low speeds. Note the added weight is normally only applied to AC motored locomotives which can reliably use the extra weight.

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Posted by Murphy Siding on Sunday, January 17, 2016 4:42 PM

    Also, why would you want an AC locomotive with A1A trucks?  They can pull harder at low speeds, but aren't you eliminating 1/3 of the adhesion to the rails?

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Posted by tree68 on Sunday, January 17, 2016 4:52 PM

beaulieu

The downside is less than the upside.  More weight allows the locomotives to pull harder at low speeds. Note the added weight is normally only applied to AC motored locomotives which can reliably use the extra weight.

Locomotives were being ballasted well before AC entered the market.

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Posted by edblysard on Sunday, January 17, 2016 5:02 PM

Both NS and CSX have/had heavy ballasted locomotives for coal drags years ago...

The C30-7A cabless boosters that BN had replaced the cab weight with ballast to keep the weight up and increae traction.

 

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Posted by ChuckCobleigh on Sunday, January 17, 2016 6:25 PM

Murphy Siding

    Also, why would you want an AC locomotive with A1A trucks?  They can pull harder at low speeds, but aren't you eliminating 1/3 of the adhesion to the rails?

Don't the A1A's have provision for "raising" the unpowered axles slightly to increase weight on wheels of the powered axles?  I seem to recall seeing something about that either in the magazine or on a link from a forum post.

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Posted by cx500 on Sunday, January 17, 2016 7:35 PM

Murphy Siding

    Also, why would you want an AC locomotive with A1A trucks?  They can pull harder at low speeds, but aren't you eliminating 1/3 of the adhesion to the rails?

 

The theory is that with electronics the 4 AC motors will provide equivalent performance to 6 DC motors.  The price differential between DC locomotives and AC locomotives kept several roads in the DC camp, especially if they did not have many significant grades.  By only having 4 motors the cost of the inverters is much reduced, making them more cost competitive.  Obviously they are not as good for dragging a full tonnage train up a heavy grade, but on a fast intermodal will perform well.

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Posted by BaltACD on Sunday, January 17, 2016 9:18 PM

Speed is a function of horsepower at the drive axle.  The A1A trucks have 1100 hp per drive axle.  1100 hp can be enough to create wheel slip.

Hauling tonnage is a matter of effective torque - 6 axle AC have 734 hp per drive axle.  734 hp per drive axle holds the rail better at maximum tonnage ratings.

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Posted by Randy Stahl on Monday, January 18, 2016 5:46 AM

I've added and subtracted ballast for years on many types of locomotives. Usually by welding slabs on the frame sides.

GE uses what looks like steel mill slag inside the frames on thier older engines, really funky stuff.

Most recently I weighed and ballasted some ex ATSF C30-7s.

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Posted by Murphy Siding on Monday, January 18, 2016 8:04 AM

Randy Stahl

I've added and subtracted ballast for years on many types of locomotives. Usually by welding slabs on the frame sides.

GE uses what looks like steel mill slag inside the frames on their older engines, really funky stuff.

Most recently I weighed and ballasted some ex ATSF C30-7s.

Randy

 

   Now I'm more curious.  How much weight did you add to the C30-7's, and what kind of use of the locomotives required the ballast?



I'm trying to imagine slabs of steel welded onto a frame.  All I can picture are big chucks of steel welded on willu-nilly, looking like a lot of post-it notes. Clown

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Posted by mudchicken on Monday, January 18, 2016 8:40 AM

Try comparing a straight SD40-2 against an SP/DRGW tunnelmotor to see ballasting on what is the same frame. The change in bodywork at the fans/cooling system does not explain the big jump in weight.

I am amazed that certain shortlines let those rascals out on certain lines.

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Posted by Randy Stahl on Monday, January 18, 2016 9:12 AM

First we cut off the light weight end plate and weld on one thats 2 inches thick instead of 1 inch then we fill the frame rails in with slabs of steel above the fuel tank.

 

We had C-30-7s that were from the BN and they weighed 10,000 lbs more than the ATSF ones so in a consist the ATSF engines were too slippery. All we did was make them about the same weight.

 

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Posted by ericsp on Monday, January 18, 2016 8:33 PM

If I remember correctly, the SD40T-2/SD45T-2 frame is about 2 feet longer than the SD40-2/SD45-2 frame.

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Posted by ndbprr on Tuesday, February 2, 2016 6:55 PM
The PRR had two SD9 engines heavily ballasted for use on the 5.98% grade at Madison Indiana. The frames were obviously much thicker than standard engines.
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Posted by Paul Milenkovic on Tuesday, February 2, 2016 9:53 PM

BaltACD

Speed is a function of horsepower at the drive axle.  The A1A trucks have 1100 hp per drive axle.  1100 hp can be enough to create wheel slip.

Hauling tonnage is a matter of effective torque - 6 axle AC have 734 hp per drive axle.  734 hp per drive axle holds the rail better at maximum tonnage ratings.

 

The previous post claimed "The theory is that with electronics (that is, more sophisticated wheel slip controls) the 4 AC motors will (a more rugged type)provide equivalent performance to 6 DC motors (a less rugged type of traction motor with in many cases less capable wheel slip controls)"

Yes, 1100 HP can result in a wheel slip at a low enough speed, but do you dispute that electronic controls can not only apply horsepower limiting at lower speeds but can sense the start of a wheel slip and rapidly adjust the traction motor controls to prevent it from developing?

What part of this do you dispute?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
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Posted by JayPotter on Wednesday, February 3, 2016 4:04 AM

The inverter control systems on AC-traction locomotives don't attempt to maximize adhesion by preventing wheel slip.  They attempt to maximize adhesion by regulating the rate of wheel creep (basically controlled slippage) in response to changing rail conditions.  For example, the creep rate that will maximize adhesion on wet rail is different from the rate that will maximize adhesion on oil-contaminated rail.  Rail conditions tend to differ somewhat among axles; and for any given rail condition, a given axle's adhesion will be less than optimal if its creep rate is either too high or too low.  

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Posted by blue streak 1 on Saturday, February 6, 2016 10:34 AM

The inverters will limit the frequency of the AC traction motors.  Is there some kind of feed back loop to prevent one inverter trying to speed up ?  An apparent advantage of the C-4s is the center axles can give an accurate speed input to the inverters.

Maybe EMD's two inverter )( one to each truck) system thought that single speed axles on each truck were good enough but now with adhesion more important decided to match GE's inverter per axle ?

 

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Posted by NorthWest on Saturday, February 6, 2016 11:55 AM

EMD's decision to switch to six inverters on the SD70ACe-P6 was primarily based on redundancy-it is far better to lose the power from one axle as opposed to one truck.

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