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Locotrol/DPU

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Locotrol/DPU
Posted by VGN Jess on Tuesday, February 9, 2021 3:54 AM

When the lead engine increases throttle or brake, in the trailing units did/do the throttles/brake handles physically move as well, or are they stationary and all "action" is electric/electronic only?

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Posted by jeffhergert on Tuesday, February 9, 2021 11:18 AM

It's all done in the electronics.  The handles don't move.

Jeff

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Posted by Max Karl on Wednesday, February 10, 2021 7:46 PM

The reverser is removed (for safety) and everything is positioned in idle/neutral. If you try to go into the locomotive and move the levers around nothing will happen since the unit it set up to be controlled by the leading unit. Looking at documentation, I believe applying locomotive and independent brakes still work.

  Max Karl, MRL and BNSF

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Posted by BigJim on Thursday, February 11, 2021 8:49 AM

Max Karl
Looking at documentation, I believe applying locomotive and independent brakes still work.

No they do not because they are cut out and pinned so they don't move.

.

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Posted by Overmod on Thursday, February 11, 2021 12:41 PM

BigJim
No they do not because they are cut out and pinned so they don't move.

I think what he means is that if you boarded a trailing locomotive and turned the pilot switch out of 'trail' or whatever, you could then move the physical handle and command the corresponding valve actuation (whether 24 or one of the 'electronic' equivalents).  It is not my understanding that the pilot switch is interlocked as the reverse and 'throttle' are, or that the brake handles even in electronic 'by-wire' control are locked out by some setting on the lead locomotive or MU/DPU connection.

I was waiting for better authorities to mention this, but it hasn't appeared 'as such' yet:  MU control of trailing units is not done by 'servo control' of the physical handles in the cab, the way some early stereo volume controls actually controlled a little motor driving the physical knob or potentiometer.  In some early MU there is a separate brake valve that is commanded via the connections to apply independent or automatic cylinder pressure; in electronic systems using the equivalent of one valve, the control does not 'cause' proportional movement of the handles to show what the valve is commanded to do.

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Posted by jeffhergert on Thursday, February 11, 2021 4:33 PM

BigJim

 

 
Max Karl
Looking at documentation, I believe applying locomotive and independent brakes still work.

 

 

No they do not because they are cut out and pinned so they don't move.

 

i've not see the independent pinned, but the side stand air brakes do have, and are supposed to be pinned if equipped.  because if the automatic isn't secured, the handle can be placed into emergency, the only position that is active with the automatic air brake when cut out.  The engineer's chair on a trailing engine has more than once swiveled around knocking the brake handle from Handle Off to Emergency.

Jeff

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Posted by zugmann on Thursday, February 11, 2021 8:30 PM

jeffhergert
i've not see the independent pinned, but the side stand air brakes do have, and are supposed to be pinned if equipped.  because if the automatic isn't secured, the handle can be placed into emergency, the only position that is active with the automatic air brake when cut out.  The engineer's chair on a trailing engine has more than once swiveled around knocking the brake handle from Handle Off to Emergency.

Some of our engines have rebuilt brake stands that are missing their "pin holes".  Someone, somewhere, doesn't understand why there were holes in those things. 

 

 The opinions expressed here represent my own and not those of my employer or any other railroad, company, or person.

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Posted by BaltACD on Friday, February 12, 2021 10:39 AM

zugmann
 
jeffhergert
i've not see the independent pinned, but the side stand air brakes do have, and are supposed to be pinned if equipped.  because if the automatic isn't secured, the handle can be placed into emergency, the only position that is active with the automatic air brake when cut out.  The engineer's chair on a trailing engine has more than once swiveled around knocking the brake handle from Handle Off to Emergency. 

Some of our engines have rebuilt brake stands that are missing their "pin holes".  Someone, somewhere, doesn't understand why there were holes in those things. 

Swiveling Engineer chairs placing trains in emergency is not limited to DPU trains.

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Posted by SD70Dude on Friday, February 12, 2021 1:37 PM

Our electronic brake valves (both Wabtec and Knorr/NYAB) have the ability to pin the automatic handle in release, but I've never encountered a scenario that would require this.  

I know that you would do this on units with Locotrol I and II when you were setting them up for DP lead operation, but those had a mechanical 26 or 30 brake stand and separate electronic brake valves (with push buttons) for DP operation.  

Greetings from Alberta

-an Articulate Malcontent

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Posted by jeffhergert on Friday, February 12, 2021 7:17 PM

zugmann

 

 
jeffhergert
i've not see the independent pinned, but the side stand air brakes do have, and are supposed to be pinned if equipped.  because if the automatic isn't secured, the handle can be placed into emergency, the only position that is active with the automatic air brake when cut out.  The engineer's chair on a trailing engine has more than once swiveled around knocking the brake handle from Handle Off to Emergency.

 

Some of our engines have rebuilt brake stands that are missing their "pin holes".  Someone, somewhere, doesn't understand why there were holes in those things. 

 

 

And we have some with the pin holes, but the pins have been removed.  Good thing the chairs can lock in place. Well most of the time.

Jeff 

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Posted by BigJim on Saturday, February 13, 2021 3:50 PM

jeffhergert

i've not see the independent pinned, but the side stand air brakes do have, and are supposed to be pinned if equipped.  because if the automatic isn't secured, the handle can be placed into emergency, the only position that is active with the automatic air brake when cut out.  The engineer's chair on a trailing engine has more than once swiveled around knocking the brake handle from Handle Off to Emergency.

Jeff

Jeff,

All of our units had a pin for both the independent and automatic brake handles. Before then, both handles were removable...the independent in release and the automatic in "handle off" position.

.

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