An SD40-2 locomotive will give you over 1500 amps of tractive effort at start, assuming good rail condition. That same locomotive will give you at best about 900 amps of dynamic.
There was a runnaway and another derailment in SoCal this weekend. Here is a article about it. ============================================================
Redlands derailment injures two, causes fire
09:14 AM PDT on Sunday, August 27, 2006
By SARAH BURGE, IMRAN VITTACHI and DAYNA STRAEHLEY The Press-Enterprise
Two separate freight trains derailed in the Inland area Saturday, injuring two railroad workers and causing a fire on a toppled locomotive south of Redlands.
Seven Union Pacific locomotives fell on their sides in a derailment near San Timoteo Canyon and Live Oak Canyon roads at 9:36 p.m. Saturday, spilling diesel fuel that caused a blaze on one of the engines, according to California Highway Patrol dispatcher Mark Riconosciuto and Capt. Jim Fuller of the Riverside County Fire Department.
The cause of the crash was unknown, said Mark Davis, a spokesman for the railroad. Davis said he did not know how fast the train was traveling on the stretch of Union Pacific tracks along San Timoteo at the time of the crash.
Two Union Pacific workers were taken to area hospitals with minor to moderate injuries, Fuller said. One of the two injured railroad workers suffered at least two broken bones and the other had cuts and bruises.
The diesel fuel fire still smoldered in one of the locomotives at 6 a.m. Sunday, sending up black smoke.
The diesel fuel from the locomotives was the only hazardous material spilled, Fuller said. A hazardous materials crew from
Actually if we were on the other hill we probably wouldn’t have seen anything but parked trains. BTW- BNSF put a few on the ground that morning too down in town.
Actually, I was speaking in terms of actually witnessing the runaways running away. That would’ve made for some cool pictures that the news organizations would’ve paid money for…
More information has come to light on this incident.
The crew appears to have suddenly lost dynamic braking descending the grade. According to a report they immediately tried to make a emergency brake application with the automatic brake valve. Because this was a light engine move (no cars), the Dynamic Brake Interlock prevented pressure build up in the locomotive brake cylinders. The crew appears to have panicked and then tried to set the handbrakes. Other Engineers I have corresponded with say the proper proceedure is to bail off the automatic brake and place the throttle in neutral or power nullifying the interlock and then use the Independent Brake Valve to stop the locomotives. It appears that the Engineer may have been improperly trained, most Conductors would not know this and would just reach for the Emergency Valve which would have no effect.
Yes, the application of the independent should override the dynamics.
I also wonder if they tried to reverse any of the locomotives. Sure, it would flatten the wheels, damaged the traction motors, and maybe ruined some rail, but it would be far less damage than actually occurred.
Most newer locomotives will not allow plugging . It’s written in the software and I think GE’s will even log a fault "plugging attempted at too high of speed "
I’m guessing that they had the dead engine feature cut in on some of the units rendering independant brakes nill . With the new electronic airbrakes in many cases if the locomotive batterys are dead the airbrake computers will not function , My guess is that this was the case .