Extended Range Dynamic Brakes


wheeler1963

wheeler1963

Aurora & Portland Owner
Does anyone have any pictures of an engine with the extended range dynamic brake blister?? Particularly an SD40-2. Sorry, let me clarify that, a real engine, not a model.
 
Ken,

These are 2 Athearn dynamic brake blisters for an SD40-2. The one on the left is the one that has been around for years. The one on the right is what they are calling an Extended Range dynamic brake blister. These are what I'm looking for in the prototype world.
100_1916.jpg


And just for fun, here are 2 extended range dynamic brake blisters with the exhaust stacks reversed. Must have been a bad day on the production line at Athearn.

100_1917.jpg
 
Fred posted some shots, but yeah, thats them. They're getting increasingly rare now, and were added for the use of DB at much slower speeds, down to about 5MPH, if I'm remembering right.
 
Let me dig a bit deeper....i've got several 100 various SD40-2 shots in the archives. I know I've seen the larger blister on GP60s.
 
Ken, Fred, Josh, Thank you for the pictures and information. I tried doing searches on railpictures.net, but didn't see any. I guess I can put them on just about any 40-2 then??
 
The bulged out part came on late SD40-2s after quieter exhausts were required. The bulged out parts held pieces of the dynamics that were displaced by the exhaust silencer. I think locos with this DB have Q fans too but not certain. No BN SD40-2s had the bulgy DBs. There is also a difference at the rear of the DB section between early and later deliveries. One has a short taper and one the taper is longer but it has been awhile and I can't remember right now. Before the bulge the extra range DBs had an extra door which is modeled by the forever Athearn DB and needs to be removed for BN models (the ones I am most familiar with).
 
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According to a PDF from EMD, extended range dynamic braking means just about what Josh says, that the dynamic brakes can be used down to 6 mph compared to about 15 mph with standard dynamics. Paul has it pretty much right about the bulge also except that Q fans were an optional part of the package. The bulge was indeed added to hold additional baffles to quiet down the dynamics, which can get really loud when you've got five or six units on a downgrade. They were first offered on GP38-2's and continued through the GP-50 line. EMD changed the entire dynamic brake arrangement on later units, thus eliminating the need for a bulge. I kind of miss the whining of the older dynamics though - I could tell when a UP freight was coming down Cajon for about 15 minutes before I ever saw the train by the whine of the dynamics. :)
 
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