helper [dynamic brakes]

[fracon]

on a 2 unit helper set suppose you took out prime mover from 1 unit and added resister grids to increase the braking power and use traction moters mu'ed from lead unit to start train would this work better to have more braking power
might prevent runaways like on csx sandpatch ?????????????

[CN Sparky]

You could put on more grids and make more braking power available, but at what point would that extra braking force exceed the coupler strength? Then you'd have a real bad runaway...

You'd need to come up with a heck of a cable system for MU'ing too.. you need the traction alternator there (driven by the engine) to create a field in the traction motors, in order to generate electricity as dynamic braking... before you even send it to the grids. At least on a DC traction motor..

[Typewriters]

Instead of creating such a hybridized two-unit set with one prime mover unit and one brake resistor unit, which would have to be heavily ballasted, you might as well just provide both units with prime movers AND massive dynamic brake capacity ... especially considering that there is not only a limit on tractive effort dictated by locomotive weight and adhesion control systems but also a limit on braking effort. That limit is also based primarily on locomotive weight.

This has of course been done - perhaps the earliest example I can think of off the top of my head was the Fairbanks-Morse H24-66 Train Master, advertised with a 2400 HP for traction rating but with a dynamic brake capacity of 3600 HP. If you find a picture of one of these, you'll see that the dynamic brake assembly really doesn't take up all that much room.

-Will Davis

[EDM5970]

I think you may also have to 'super-size' your TMs to provide that much more amperage to the larger DB grids. Just where would these larger TMs go? I think the current systems are pretty well balanced in terms of current capacity.

If it ain't broke, don't fix it-