GP40 wrote: METRO wrote:I've always wondered how much dynamic breaks used to cost? I've not seen any newer engines without it, but I know several roads (CNW, CRI&P, NKP ECT) didn't equip certain road engines with it. However if a line saves on maintainance, couldn't that offset the initial cost of dynamics?1. One reason why the RR's you mentioned did purchased dynamic brakes was they were first marketed by the builders as mountain RR equipment and the dynamics quit at 20 MPH.2. Their engineers were mostly still steam era and they were used to using the automatic train brake as their primary. 3. As the dynamics improved in performance with extended range and RR's got into serious operational cost cutting and also when certain modern cars seemed to have problematic train brake(TTX cars had a reputation of going into emergency when given a low to moderate brakepipe reduction). Not to mention the modern practice of run through power .Then Dynamics became the rigeur for all road locomotive purchases.There were of course the serious holdouts. The MoPac purchased a few DB equipped SD40-2's only because they had interline those uints on unit coal trains.
METRO wrote:I've always wondered how much dynamic breaks used to cost? I've not seen any newer engines without it, but I know several roads (CNW, CRI&P, NKP ECT) didn't equip certain road engines with it. However if a line saves on maintainance, couldn't that offset the initial cost of dynamics?
1. One reason why the RR's you mentioned did purchased dynamic brakes was they were first marketed by the builders as mountain RR equipment and the dynamics quit at 20 MPH.
2. Their engineers were mostly still steam era and they were used to using the automatic train brake as their primary.
3. As the dynamics improved in performance with extended range and RR's got into serious operational cost cutting and also when certain modern cars seemed to have problematic train brake(TTX cars had a reputation of going into emergency when given a low to moderate brakepipe reduction). Not to mention the modern practice of run through power .Then Dynamics became the rigeur for all road locomotive purchases.
There were of course the serious holdouts. The MoPac purchased a few DB equipped SD40-2's only because they had interline those uints on unit coal trains.
4. Because the railroads were too cheap regarding both the original purchase price as well as the cost of extra maintenance. After all, it's how the C&NW got it's nickname.Cheap&NothingWorks
FYI-
Dynamic brake force chart from Al Krug's site
chad thomas wrote: FYI-Dynamic brake force chart from Al Krug's site
You posted a chart do you know what the information means? is it accurate?
That chart is very accurate Wabash, that is the same chart that was given to me when I went through locomotive engineer training program, look at the speed less than 20mph that is when the dynamic realy works its best.
Rodney
hogger BNSF
wabash1 wrote: chad thomas wrote: FYI-Dynamic brake force chart from Al Krug's siteYou posted a chart do you know what the information means? is it accurate?
As to what it means...
When the TMs are in dynamic the energy is fed to the resistance grids (and a portion to the fan). As the speed of the TMs increases more energy is sent to the grid and more resistance to the TM rotation is offered, and thus more brakeing effort. this is a linear increase up to the limit of the grid (about 750 amps). At this point (24 mph, or 12 mph with extended range, give or take a bit) the brakeing force is at its max. As the speed increases beyond this point the energy to the grid is chopped so that the average current does not exceede the max. As the speed continues to increase the brakeing has less and less effect because less and less of a portion of energy can be dissipated.
Rodney Beck wrote: That chart is very accurate Wabash, that is the same chart that was given to me when I went through locomotive engineer training program, look at the speed less than 20mph that is when the dynamic realy works its best. Rodneyhogger BNSF
Thanks to Chris / CopCarSS for my avatar.
You mainly learn how to use the dynamic brakes is when you are in the seat running (i.e.) it is all feel on how the train reacts, the trick is to get the train bunched up then slowly more dynamic. The first few times I got the s kicked out out me then more seat time it got better.
chad thomas wrote: wabash1 wrote: chad thomas wrote: FYI-Dynamic brake force chart from Al Krug's siteYou posted a chart do you know what the information means? is it accurate? As to what it means... When the TMs are in dynamic the energy is fed to the resistance grids (and a portion to the fan). As the speed of the TMs increases more energy is sent to the grid and more resistance to the TM rotation is offered, and thus more brakeing effort. this is a linear increase up to the limit of the grid (about 750 amps). At this point (24 mph, or 12 mph with extended range, give or take a bit) the brakeing force is at its max. As the speed increases beyond this point the energy to the grid is chopped so that the average current does not exceede the max. As the speed continues to increase the brakeing has less and less effect because less and less of a portion of energy can be dissipated.
I dont agree with the post because it shows using standard dynamic but keeps refering to extended range. the extended range numbers you need to remeber is 24-18-12-6. this is when the grids drop out to offer more resistance. and in moderern engines the dynamic is at 900-950 amps not 750 as standard amp ( sd-40) dynamic,
I'm looking at the possibility of some seat time this fall on our line. As it stands, our primary locomotive will be our RS-3 (no dynamics, No. 6 brakestand), but our backup may well have dynamics (one of our two Century series ALCO's). Decent overall trainhandling notwithstanding, this is the real challenge:
You're looking south, from about a .5% grade toward a ~1% grade on the other side of the "Camel's Hump." It's fun - from heavy throttle to a brake application in the length of the train. With regular braking, the train stays stretched (make an initial set and bail off the independent). The fun will be in gracefully going from stretch to bunched as the dynamics come into play.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
I can not do that tree I would get flagged for power brakeing i.e. air set above throttle notch 4 and above 20mph.
you have diffrant train handling when using dynamic, if in dynamic and also using air make sure you nock the air off and brakes are releasing on rear before you get any throttle, if not you will get a knuckle. release dynamic slowly because the same forces that bunched the train has to be released slowly if not a heavy run out is possible and yep a knuckle and maybe a draw bar. in other words if using dynamic it bunches train streach it out slowly and then go. I wont say air is better than dynamic or dynamic is better than air. they both are great for differant uses.
Murphy Siding wrote: Are dynamic brakes used for braking on reletively flat tracks, or garden variety hills, or just on the *big* hills?
The newer engines have extended range and they work most effectively at slower speeds .
GTWEngineer wrote: Murphy Siding wrote: Are dynamic brakes used for braking on reletively flat tracks, or garden variety hills, or just on the *big* hills?I use DB on flat track , going down hills or grades , BUT when I am going thru major curves or turnouts I try and stay away from using it but if I am in DB going thru a curve or turnout I don't use it much . The newer engines have extended range and they work most effectively at slower speeds .
Because to much dynamic can be applied and buckle the train or pick the switch, care must be done in those areas, if I still need my dynamics all I have to do is set a min reduction.
Rodney Beck wrote: Because to much dynamic can be applied and buckle the train or pick the switch, care must be done in those areas, if I still need my dynamics all I have to do is set a min reduction. Rodney
Too much force on a curve can also turn a rail over. Our rules want us going thru turnouts or curves at no more than position 4, about midway in the dynamic range. Enough to keep the head end from rolling out.
Jeff
Rodney Beck wrote: I can not do that tree I would get flagged for power brakeing i.e. air set above throttle notch 4 and above 20mph.Rodney
No power braking involved. Throttle to idle as you crest the hill, then make an initial set, especially if you're headed south onto the 1% downgrade. Track speed is 40, but our train is scheduled at 25, with 30 being our arbitrary max. Train length through most of the season is only three cars, with up to 5 at peaks.
We occasionally make a flag stop about a mile and a half further down the track (southbound) and have a 20 mph bridge another mile further.
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