In another forum we are discussing ways to start a reluctant engine and its come up that there are also problems getting them stopped. Locomotive engine air intakes are too big to throw a rag in it to block off the air. On drill rig engines it is a requirement that a damper be installed to accomplish the same thing. EMD was surprised to find that their customers were putting these things on their engines and it was decided that EMD had to at least test and approved these devices. The worry is that the blower quill shaft is marginal for this type of abuse. Well the tests were okay but don't come looking for warranty for a broken shaft. On other engines I have read that in the case of a runaway engine, i.e.. engine runs on the lube oil leaking from a turbo seal, that they try to stop it with a CO2 fire extinguisher in the air intake to block off oxygen. Marine engine rooms have large fire suppression system that you would think they could tap into. GE has enough fire that you would think that they would look into this idea.
FWIW,
Quill shafts are a common point of weakness of all GM diesel projects. In my military life, I am familiar with the 6V-53, the 8V-71T, and the AVDS-1790 plants (M113FOV, M109 howitzer, and M60 tank family respectively). All of them have weak quill shafts.