I understand the use of DPU(s) in the operation of trains.
Is is permissible in switching of the train, for the Engineer to operate the DPU as if it was a remote control engine. The Engineer stationed on the lead locomotive and using the DPU to move cuts of cars as necessary in whatever switching/spotting of cars for industry or other purposes?
A remote control unit on the rear of the train would help in dealing with facing point sidings.
With the caveat that I have no first hand knowledge of the design of either DPU or remote control hardware/software, I would wonder if safety rules would prevent using a DPU for remote control operation. I would think that remote control operation would require an immediate setting the throttle to idle and a service application of the airbrakes. IIRC, DPUs are set up to maintain the current throttle settings for a few minutes after loss of signal.
Full disclosure I donāt work for a railroad but my understanding is that in order for a DPU to be controlled it has to be connected to the main locomotive. Railroads also have locomotives that are remote controlled i.e. can be operated from the ground and are used in yards. I think they use a different control system from a DPU on a freight train.
DPU and RCO are purposely different, and NOT intended for one to be controlled by the other. Personally Iād like it to stay that way.
Now, I could see a ādual-controlā unit that could be switched from DPU to RCO control, with normal MU handling attached units in the unmanned consist. Youād then use RCO rules with a typical RCO pack to operate the locomotives āseparateā from the head-end consist, and then āwhen doneā switch back to DPU. But all the speed and presence constraints of safe RCO would apply to any units being āremote-controlledā whether from the ground or from some kind of droneā¦
It can be done. I know of an engineer who did it spotting a loaded coal train at a location where it had to be broken up for interchange.
DONāT DO IT!
The engineer didnāt get into trouble, but was told not to do it again. (That location now has a better interchange where trains can be interchanged whole.)
The problem is if communication is lost between lead controlling engine and the DP, the DP will continue in power for 90 minutes in the last command it received. In a train if it happens, an air brake application will signal the DP to idle down. If itās not connected to the brake pipe, it canāt receive that signal.
So you could have it shoving cars off the track or out the other end of a track. Or you could have it take off in the other direction. Either way itās not a good thing to happen.
To use the DP to switch, you have to get an engineer on the DP and either unlink it, or if equipped, suspend DP operation. Suspending came out a year or so back and doesnāt require a complete unlinking.
I havenāt had to suspend DP operation yet, and would have to pull out the instructions to do so. I know of it being used once when one of the land barges got a wrong end drawbar.
Jeff
Jeff, thanks for the info on DP operations. I remembered that DP will continue on for a while after communication is lost, but didnāt think it was 90 minutes. As mentioned earlier, I donāt have direct knowledge of remote control operations, but my paranoid side thinks the appropriate response for loss of communication is locomotive going to idle coupled with a service activation of the airbrakes - i.e. bring the RC train to a stop.
I asked the question because there is a YouTube video of a DPU unit being used to place 107 empty grain cars on three track at an industry using the DPU controlled from the lead locomotive that was placed in a side track to facilitate shoving the cars into their tracks. Conductor was on the lead end of the shove communicating to the engineer by radio.
The DP continues in power for 90 minutes and then will idle down and cut out its brake valve. When in such comm loss, a brake application will cause it to do so immediately. If safe to do so, you can continue with comm loss to a point where comm can be restored.
In dynamics during comm loss, the DP will hold that command indefinitely. Itās a safety feature for mountainous territory with long down grades. To signal a DP in that circumstance, the train has to be stopped and the brake valve placed in emergency. Then the DP should go to idle and cut out its brake valve.
I try to avoid placing DPUāS in dynamics unless absolutely necessary or i havenāt observed any significant comm loss. Thatās because of that holding feature.
Jeff
Jeff, thanks for filling in the details.
The 90 minute hold makes sense with DPU operation especially since the DPU hardware/software will sense and act upon a reduction in trainline pressure. In RCO, there is no direct operator access to the brake valves, which is why I would design an RCO system to bring the train to a stop if communication is lost.
UP managementās āDON"T DO ITā to RCO with DPU equipment sounds very reasonable to me.
To us non-engineers/non-conductors who love trains, I really appreciate you guys explaining these things to us! Very interesting topic!
