Pushers

Watched a really long tank car train go by led by a UP and two BNSFs and a lonely loud, slightly smoking UP pusher bringing up the rear.  I know the engineer controls the rear engine from the cab.  How does s/he know the pusher is really shoving and not slacking?

Because he/she can see what the rear DPU is doing by watching it on the computer screen in the laed unit.

  Pusher amperage readout, wheel RPMs or ? so right amount of push/retarding is applied, especially around curves and hills.  What about excessive pusher wheel slippage and other things not evident unless someone was riding the pusher? 

When engineer begins brake handling, does pusher begin pushing/exhausting air from its end to speed up brake release/application?

This is just for a general "generic" train, knowing there are probably a lot of "it depends" involved.

Because he/she can see what the rear DPU is doing by watching it on the computer screen in the lead unit.

HW  can you give us a little more, watching what?,

No, the actual computer screen right in front of the lead unit's Engineer.

  gauges?  Wheel slip, amp meter   I suppose if radio communications is lost the engine drops  it's  load?

No, the rear DPU will stay in its "last state" for some 30 minutes, or until it senses a brake pipe reduction, then it drops its load.

  Do these rear pushers  engines get skidded the odd time when the train  brakes are used?

No, they do not "get skidded", whatever THAT means. The rear DPUs are totally controlled by the lead unit's Engineer.

  Can you reset a ground relay from the lead engine?

No.

Slightly different situation but perhaps a similar question.  The CSX Old Main is pusher territory from Brunswick, MD eastbound to Parr's Ridge in Mt. Airy, mostly for coal drags. The pushers cut off on the fly just past the ridge crest.  Are the pushers DPU's going up the grade or independently controlled by the pusher crew?  And how is the "on the fly" cutoff accomplished between the lead units and the pushers?

Thanks.

Poppyl

  I would still  still like to know what happens if communications are lost, I can't believe the engine would carry on with the last instruction for any length of time.... 

I don't know why you find it so hard to believe that the DP's will continue the last command if radio communication is lost.

From rule 105.8.2 of the BNSF Air Brake & Train Handling book of rules.

(Emphasis is mine)...

If a radio communication has been interrupted, each remote consist will do the following:
1.Continue to operate on the last throttle and air brake command received via the radio.
2.If no changes in the actual brake pipe pressure are detected at the remote:
a.Continue to act on last command received for no longer than 90 minutes.
b. If radio communication has not been re-established, at the end of 90-minute override, remote will drop throttle (or dynamic brake) to idle at a rate of 3 seconds per throttle position, and automatic brake valve will cut out.

As HW said, you sure as heck don't want those pushers to drop to idle when you are  climbing a long hill and they lose radio contact. The train at best would stall and most likely would be in several pieces.

Even the old 1970s era Locotrol had an OverRide button that did basically the same thing (but for only 30 minutes as I recall). We engineers were ALWAYS pushing that OverRide button just in case the radio comm was temporarily lost. The current era DPs just automatically do what we always did anyway.

Further BNSF rule...

If a remote unit senses a brake application or release via the brake pipe without receiving a radio command to reduce brake pipe pressure or to release the brakes, the unit will:
Try to check with the lead unit via radio.
1.If no response is received, the remote unit will:
a. Step the throttle or dynamic brake to IDLE at 3 seconds per step.
b. Cut out the brake valve on the remote.
c. Limit to an ISOLATE mode.
Note: The engineer uses the brake pipe as a backup communication tool, as described in steps 1 and 2 above, to eliminate tractive effort or dynamic braking.

More BNSF rule..

During a communications interruption between the lead and remote(s), keep the train moving, if possible, to a location where communications might improve.
While using a remote DP/IDP unit at the rear of the train without a two-way ETD, a communication interruption that exceeds 5 minutes should be considered an en route failure of an ETD.

That last sentence means reduce max speed to 30 mph.

Next thing coming  a  satellite will be telling you when to throttle back or isolate a unit.

When engineer begins brake handling, does pusher begin pumping/exhausting air from its end to speed up brake release/application?

Have not read a reply to this part of my question yet.