Functional Purpose of a Diesel Locomotive Brake Wheel?

Well, yeah, you need to set handbrakes to hold the train. Not many will argue about that. Still not clear on your point, though.

The train that ran away at Lac Magentic had hand brakes applied on all engines and one or two cars. When the push/pull securement test was done, it was with the independent applied. It shoud’ve been done with the independent released. The independent applied gave more braking power than the hand brakes alone, so it seemed secured. Once the fire dept shut down the only engine running, shutting down the air compressor,