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Power moves

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  • Member since
    December 2015
  • From: Shenandoah Valley
  • 9,091 posts
Power moves
Posted by BigDaddy on Tuesday, November 10, 2020 6:04 PM

Maybe this is more of a Trains.com question,but I'm going to sneak it in. 

The daily recap of one of the Youtube railfan videos show 20 something locos moving as a consist.  Is there a neutral in locos, where they are easy to pull or do they all move under power?

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    September 2003
  • From: Omaha, NE
  • 10,594 posts
Posted by dehusman on Tuesday, November 10, 2020 6:35 PM

BigDaddy
Is there a neutral in locos, where they are easy to pull or do they all move under power?

Short answer is no.  There is no "neutral" gear.  Railroad engines have one gear and its always engaged.  

What they do is make the engine "off line", so no power is applied to the traction motors, done through putting the power controls in "neutral" and setting various electrical switches in the cab.  The traction motors just freewheel along.

Locomotives can be set up dead in tow also, where they aren't running, completely dead and not electrically connected in any way.  

For power moves they want the MU cables and air lines connected so the engines maintain wheel slip protection.

Dave H. Painted side goes up. My website : wnbranch.com

  • Member since
    February 2018
  • From: Danbury Freight Yard
  • 441 posts
Posted by OldEngineman on Tuesday, November 10, 2020 9:53 PM

I remember on December 24, 1984, taking all the engines out of Oak Point Yard (in the Bronx) to Selkirk (for some reason they didn't want to leave them in the yard over the holiday).

15 in total. The first 3 or 4 were MU'ed for power, the rest of them were isolated and just dead weight along for the ride. And 15 engines is A LOT of "dead weight" to be hauling around, you had to be careful. Once they're moving, they don't want to stop!

Got them up to Selkirk in good time (light engines could go 60 back in the day), and instead of backing them into the fuel plant, I walked all the way to the other end and ran from the tail engine (an SW 1500) up to the fuel pad. Stopped short of the derail, put the reverser on the control stand, and put a hand brake on.

Did I tell you about the part that happened next? I was in the fuel shed filling out the engine report when somebody yelled, "run, run!". I looked out and here comes the switch engine I was just on, off the track, coming straight at the shed. Got out of there in a hurry!

The road foreman tried to give me a grillin' inside the crew room, but it weren't my fault! Someone had tried to move the engines up onto the pad, without checking the derail first.

So... called for a crew cab to Albany-Rensselaer station, jumped on Amtrak 64 to Grand Central, called up "Communicar" (formerly known as Skull's Angels) for a limo back to Oak Point (which by then was all locked up), told them I was the yardmaster with one guy to pick up, got the ride back to the Bronx, got in my car, made it 65 miles home just in time for a nice Christmas Eve!

  • Member since
    March 2002
  • From: Milwaukee WI (Fox Point)
  • 11,414 posts
Posted by dknelson on Wednesday, November 11, 2020 11:02 AM

I recall reading - not a railroader so this is not direct knowledge - that a locomotive dead in tow was not to be moved faster than it was rated for in terms of maximum speed.  I do recall seeing a BN freight train or two come through the diamond at Rochelle at what seemed to be a reduced speed compared to most, and in the middle of the trains were older EMD SW type switchers being moved.  Presumably those switchers had a lower maximum speed than a road locomotive.

Dave Nelson  

  • Member since
    December 2001
  • 1,165 posts
Posted by mvlandsw on Wednesday, November 11, 2020 9:27 PM

The maximum allowable speed for most locomotives with traction motors is set by the maximum rotational speed that the motors can survive. If the motors rotate too fast they begin to fly apart. The track speed that this occurs at is determined by the gear ratio between the motor and axle and the wheel diameter.

Mark Vinski

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